Limbach (LMB) 10-Q 12 Aug 21 2021 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 11, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-36541
Entity Registrant Name	LIMBACH HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5399422
Entity Address, Address Line One	1251 Waterfront Place
Entity Address, Address Line Two	Suite 201
Entity Address, City or Town	Pittsburgh
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15222
City Area Code	412
Local Phone Number	359-2100
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	LMB
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		10,267,841
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001606163
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 27,693	$ 42,147
Restricted cash	113	113
Accounts receivable, net	94,615	85,767
Contract assets	70,815	67,098
Income tax receivable	891	0
Other current assets	5,599	4,292
Total current assets	199,726	199,417
Property and equipment, net	17,433	19,700
Intangible assets, net	11,473	11,681
Goodwill	6,129	6,129
Operating lease right-of-use assets	16,852	18,751
Deferred tax asset	6,393	6,087
Other assets	283	392
Total assets	258,289	262,157
Current liabilities
Current portion of long-term debt	8,454	6,536
Current operating lease liabilities	4,122	3,929
Accounts payable, including retainage	66,954	66,763
Contract liabilities	39,179	46,648
Accrued income taxes	0	1,671
Accrued expenses and other current liabilities	19,215	24,747
Total current liabilities	137,924	150,294
Long-term debt	24,721	36,513
Long-term operating lease liabilities	13,454	15,459
Other long-term liabilities	4,031	6,159
Total liabilities	180,130	208,425
Commitments and contingencies
STOCKHOLDERS’ EQUITY
Common stock, $0.0001 par value; 100,000,000 shares authorized, 10,251,696 issued and outstanding at June 30, 2021 and 7,926,137 at December 31, 2020	1	1
Additional paid-in capital	83,589	57,612
Accumulated deficit	(5,431)	(3,881)
Total stockholders’ equity	78,159	53,732
Total liabilities and stockholders’ equity	$ 258,289	$ 262,157

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par or stated value per share (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares, issued (in shares)	10,251,696	7,926,137
Common stock, shares, outstanding (in shares)	10,251,696	7,926,137

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue	$ 121,019	$ 135,185	$ 234,363	$ 273,957
Cost of revenue	102,329	114,850	198,444	235,398
Gross profit	18,690	20,335	35,919	38,559
Operating expenses:
Selling, general and administrative	17,232	13,752	34,377	30,552
Amortization of intangibles	104	274	208	417
Total operating expenses	17,336	14,026	34,585	30,969
Operating income	1,354	6,309	1,334	7,590
Other income (expenses):
Interest expense, net	(452)	(2,137)	(1,716)	(4,295)
Gain (loss) on disposition of property and equipment	94	(13)	8	17
Loss on early debt extinguishment	0	0	(1,961)	0
Gain (loss) on change in fair value of warrant liability	0	(102)	14	59
Total other expenses	(358)	(2,252)	(3,655)	(4,219)
Income (loss) before income taxes	996	4,057	(2,321)	3,371
Income tax provision (benefit)	264	1,110	(771)	476
Net income (loss)	$ 732	$ 2,947	$ (1,550)	$ 2,895
Income (loss) per common share:
Basic (in usd per share)	$ 0.07	$ 0.38	$ (0.16)	$ 0.37
Diluted (in usd per share)	$ 0.07	$ 0.37	$ (0.16)	$ 0.37
Weighted average number of shares outstanding:
Basic (in shares)	10,251,696	7,845,515	9,737,801	7,821,594
Diluted (in shares)	10,469,028	7,905,368	9,737,801	7,878,246

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2019		7,688,958
Beginning balance at Dec. 31, 2019	$ 46,870	$ 1	$ 56,557	$ (9,688)
Stock-based compensation	295		295
Shares issued related to vested restricted stock units (in shares)		104,905
Shares issued related to vested restricted stock units	0
Net (loss) income	(52)			(52)
Ending balance (in shares) at Mar. 31, 2020		7,793,863
Ending balance at Mar. 31, 2020	47,113	$ 1	56,852	(9,740)
Beginning balance (in shares) at Dec. 31, 2019		7,688,958
Beginning balance at Dec. 31, 2019	46,870	$ 1	56,557	(9,688)
Net (loss) income	2,895
Ending balance (in shares) at Jun. 30, 2020		7,853,377
Ending balance at Jun. 30, 2020	50,200	$ 1	56,992	(6,793)
Beginning balance (in shares) at Mar. 31, 2020		7,793,863
Beginning balance at Mar. 31, 2020	47,113	$ 1	56,852	(9,740)
Stock-based compensation	140		140
Shares issued related to vested restricted stock units (in shares)		59,514
Shares issued related to vested restricted stock units	0
Net (loss) income	2,947			2,947
Ending balance (in shares) at Jun. 30, 2020		7,853,377
Ending balance at Jun. 30, 2020	50,200	$ 1	56,992	(6,793)
Beginning balance (in shares) at Dec. 31, 2020		7,926,137
Beginning balance at Dec. 31, 2020	53,732	$ 1	57,612	(3,881)
Stock-based compensation	677		677
Shares issued related to vested restricted stock units (in shares)		89,446
Shares issued related to vested restricted stock units	0
Tax withholding related to vested restricted stock units	(183)		(183)
Stock issued related to employee stock purchase plan (in shares)		8,928
Shares issued related to employee stock purchase plan	92		92
Shares issued related to exercise of warrants (in shares)		172,869
Shares issued related to the exercise of warrants	1,989		1,989
Shares issued related to offering (in shares)		2,051,025
Shares issued related to sale of common stock	22,773		22,773
Net (loss) income	(2,282)			(2,282)
Ending balance (in shares) at Mar. 31, 2021		10,248,405
Ending balance at Mar. 31, 2021	76,798	$ 1	82,960	(6,163)
Beginning balance (in shares) at Dec. 31, 2020		7,926,137
Beginning balance at Dec. 31, 2020	53,732	$ 1	57,612	(3,881)
Net (loss) income	(1,550)
Ending balance (in shares) at Jun. 30, 2021		10,251,696
Ending balance at Jun. 30, 2021	78,159	$ 1	83,589	(5,431)
Beginning balance (in shares) at Mar. 31, 2021		10,248,405
Beginning balance at Mar. 31, 2021	76,798	$ 1	82,960	(6,163)
Stock-based compensation	636		636
Shares issued related to vested restricted stock units (in shares)		3,291
Shares issued related to vested restricted stock units	0
Tax withholding related to vested restricted stock units	(7)		(7)
Net (loss) income	732			732
Ending balance (in shares) at Jun. 30, 2021		10,251,696
Ending balance at Jun. 30, 2021	$ 78,159	$ 1	$ 83,589	$ (5,431)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net (loss) income	$ (1,550)	$ 2,895
Adjustments to reconcile net (loss) income to cash (used in) provided by operating activities:
Depreciation and amortization	2,964	3,140
Provision for doubtful accounts	70	27
Stock-based compensation expense	1,313	435
Noncash operating lease expense	2,091	2,025
Amortization of debt issuance costs	220	1,080
Deferred income tax provision	(306)	798
Gain on sale of property and equipment	(8)	(17)
Loss on early debt extinguishment	1,961	0
Gain on change in fair value of warrant liability	(14)	(59)
Changes in operating assets and liabilities:
Accounts receivable	(8,918)	3,588
Contract assets	(3,717)	4,901
Other current assets	(1,306)	(166)
Accounts payable, including retainage	190	(19,519)
Prepaid income taxes	(891)	(171)
Accrued taxes payable	(1,671)	(11)
Contract liabilities	(7,469)	16,254
Operating lease liabilities	(2,004)	(2,399)
Accrued expenses and other current liabilities	(5,450)	9,419
Other long-term liabilities	(114)	237
Net cash (used in) provided by operating activities	(24,609)	22,457
Cash flows from investing activities:
Proceeds from sale of property and equipment	361	64
Advances to joint ventures	0	(1)
Purchase of property and equipment	(501)	(660)
Net cash used in investing activities	(140)	(597)
Cash flows from financing activities:
Proceeds from Wintrust Term Loan	30,000	0
Payments on Wintrust Term Loan	0	7,250
Payments on 2019 Revolving Credit Facility	0	(7,250)
Prepayment penalty and other costs associated with early debt extinguishment	(1,376)	0
Proceeds from the sale of common stock	22,773	0
Proceeds from the exercise of warrants	1,989	0
Payments on finance leases	(1,318)	(1,285)
Payments of debt issuance costs	(593)	0
Taxes paid related to net-share settlement of equity awards	(401)	(90)
Proceeds from contributions to Employee Stock Purchase Plan	221	0
Net cash provided by (used in) financing activities	10,295	(1,375)
(Decrease) increase in cash, cash equivalents and restricted cash	(14,454)	20,485
Cash, cash equivalents and restricted cash, beginning of period	42,260	8,457
Cash, cash equivalents and restricted cash, end of period	27,806	28,942
Noncash investing and financing transactions:
Right of use assets obtained in exchange for new operating lease liabilities	156	0
Right of use assets obtained in exchange for new finance lease liabilities	336	1,050
Right-of-use assets disposed or adjusted modifying operating leases liabilities	36	586
Right-of-use assets disposed or adjusted modifying finance leases liabilities	0	(64)
Interest paid	1,741	3,250
Cash paid for income taxes	2,096	734
Wintrust Term Loan
Cash flows from financing activities:
Payments of Term Loans	(2,000)	0
2019 Refinancing Term Loan
Cash flows from financing activities:
Payments of Term Loans	$ (39,000)	$ 0

Organization and Plan of Busine

Organization and Plan of Business Operations	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Plan of Business Operations	Organization and Plan of Business Operations Limbach Holdings, Inc. (the “Company,” “we” or “us”), is a Delaware corporation headquartered in Pittsburgh, Pennsylvania that was formed on July 20, 2016, as a result of a business combination with Limbach Holdings LLC (“LHLLC”). The Company’s condensed consolidated financial statements include the accounts of Limbach Holdings, Inc. and its wholly-owned subsidiaries, including LHLLC, Limbach Facility Services LLC, Limbach Company LLC, Limbach Company LP, Harper Limbach LLC, and Harper Limbach Construction LLC. As of January 1, 2021, the Company renamed its existing two reportable segments to reflect our two distinct approaches to our customer base and to better align with our owner direct strategy. The previously named Construction Segment is now known as General Contractor Relationships (“GCR”); the previously named Service Segment is now known as Owner Direct Relationships (“ODR”). The Company operates in two segments that are based on the relationship with its customer, (i) GCR, in which the Company generally manages new construction or renovation projects that involve primarily heating, ventilation, and air conditioning (“HVAC”), plumbing, or electrical services awarded to the Company by general contractors or construction managers, and (ii) ODR, in which the Company provides maintenance or service primarily on HVAC, plumbing or electrical systems, building controls and specialty contracting projects direct to, or assigned by, building owners or property managers. This work is primarily performed under fixed price, modified fixed price, and time and material contracts over periods of typically less than two years. The Company's customers operate in diverse industries including, but not limited to, healthcare, life sciences, data centers, industrial and light manufacturing, entertainment, education and government. The Company operates primarily in the Northeast, Mid-Atlantic, Southeast, Midwest, and Southwestern regions of the United States. Impact of the COVID-19 Pandemic In March 2020, the World Health Organization declared the outbreak of COVID-19 a global pandemic. The COVID-19 pandemic has caused significant disruption and volatility on a global scale resulting in, among other things, an economic slowdown and the possibility of a continued economic recession. In response to the COVID-19 outbreak, national and local governments around the world instituted certain measures, including travel bans, restrictions on group events and gatherings, shutdowns of certain non-essential businesses, curfews, shelter-in-place orders and recommendations to practice social distancing. The various governmental actions have abated over time, but remain applicable to Limbach's operations in various ways, often varying by state. In some instances, these orders continued to affect certain projects in our GCR and ODR segments into the first quarter of 2021. In limited instances, during fiscal 2020, projects chose to shutdown work irrespective of the existence or applicability of government action. In most markets, construction is considered an essential business and Limbach continued to staff its projects and perform work during fiscal 2020 and into 2021, and most of the projects that were in progress at the time shutdowns commenced were restarted. The Company’s branches are expecting building owners to maintain or retrofit current facilities in lieu of funding larger capital projects as the effects of the pandemic remain ongoing and uncertain. During fiscal 2020 and through the second quarter of 2021, the Company continued to take several actions to combat the adverse impacts that the COVID-19 outbreak had on our business including, but not limited to the following: • Identification of projects that have been shut down and methods for seeking to preserve any contractual entitlement that may exist to recover monetary and time impacts; • Establishment of a task force to identify possible types and areas of impact from COVID-19 for both shutdown and continuing operations; • Examination of the Company's productivity and potential impact on gross profit as a result of COVID-19; • Implementation of the Company's pandemic response plan; • Implemented our furlough and work schedule reduction plans, as well as permanent reductions in force; and • Temporarily suspended substantially all discretionary, non-essential expenditures, including but not limited to, auto allowances, deferral of rent ranging between 1 and 3 months; and • A temporary 10% salary reduction for a select group of corporate and regional management, along with a 10% fee reduction in director compensation, and cost reduction opportunities identified by our external consultant. During the month of July 2020, with the substantial restart and return of project and service work, the Company removed the 10% salary reduction for the select group of corporate and regional management, along with the fee reduction for director compensation, returned auto allowances, reinstated positions, removed schedule reduction plans and discontinued our hiring freeze. During the remainder of 2020 and into 2021, the Company reinstituted limited travel and in-person meetings, along with encouraging employees to return to the office, field and training settings in a partial, flexible manner that is consistent with our Work From Home Policy and our COVID-19 Policy. The Company has remained steadfastly committed to our COVID-19 Policy as our work environment evolves in response to the changing landscape of the pandemic and in response to the increasing availability of vaccinations. We continue to monitor the short and long term impacts of the pandemic. While our employees and customers have adapted to a new work environment and there continues to be scientific, societal and economic progress to address the effect of COVID-19, there remains significant uncertainty about the future impacts of the pandemic, including the potential effects on our operations. We remain cautiously optimistic about the markets in which we operate and the customers we serve; however, the spread of more contagious variants of the virus, including the current rapid increase of the Delta Variant, may impact economic activity and could cause projects to be delayed or canceled, or we may experience access restrictions to our customers’ facilities and project sites. Additionally, the spread of the Delta Variant has the near-term possibility of causing some state and local governments where we work to reinstitute restrictions that could impact our customers, vendors and our own ability to perform existing projects. The ongoing effects of the pandemic, including decreased consumer confidence and economic instability, can make it extremely difficult for our customers, our vendors and us to accurately forecast and plan future business activities, and could cause constrained spending on our services, delays and a lengthening of our business development efforts, the demand for more favorable pricing or other terms, and/or difficulty in collection of our accounts receivable. Our clients may face budget deficits or other financial constraints that prohibit them from funding proposed and existing projects. During the fourth quarter of 2020 and the first half of 2021, several of our business units experienced slowdowns in the closing of sales related to the ongoing effects of the pandemic, which impacted our revenue and profitability. These impacts may continue as the pandemic persists. Further, ongoing economic instability in the global markets, including from the pandemic, could limit our ability to access the capital markets at a time when we would like, or need, to raise capital, which could have an impact on our ability to react to changing business conditions or new opportunities. If economic conditions remain uncertain or weaken, or spending continues to be reduced, our financial condition and results of operations may be adversely affected. The Company continues to take steps to minimize the adverse impacts of the COVID-19 pandemic on its business and to protect the safety of its employees, and the Company continues to emphasize wearing of masks, more frequent washing of hands and tools, social distancing, and work protocols. Limbach's COVID-19 Policy is based on the best practices provided by the Centers for Disease Control and Prevention (“CDC”) and Occupational Safety and Health Administration for essential workers. Our updated Work From Home Policy, along with the Company's business continuity planning and information technology enhancements enabled an orderly transition to remote work and facilitated social distancing for salaried employees. Although the Company has not mandated vaccinations for employees, it is encouraging all employees to be vaccinated, in accordance with CDC recommendations. Testing and inpatient treatment for COVID-19 is covered under our medical plan and fees have been waived since the onset of the pandemic. Counseling is available through our employee assistance plan to assist employees with financial, mental and emotional stress related to the virus and other issues.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Basis of Presentation Condensed Consolidated Financial Statements The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with instructions to the Quarterly Report on Form 10-Q and Rule 8-03 of Regulation S-X for smaller reporting companies. Consequently, certain information and note disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. Readers of this report should refer to the consolidated financial statements and the notes thereto included in our most recent Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 25, 2021. Unaudited Interim Financial Information The accompanying interim Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Stockholders’ Equity and Condensed Consolidated Statements of Cash Flows for the periods presented are unaudited. Also, within the notes to the Condensed Consolidated Financial Statements, we have included unaudited information for these interim periods. These unaudited interim Condensed Consolidated Financial Statements have been prepared in accordance with GAAP. In our opinion, the accompanying unaudited Condensed Consolidated Financial Statements contain all normal and recurring adjustments necessary for a fair statement of the Company’s financial position as of June 30, 2021, its results of operations and its cash flows for the three and six months ended June 30, 2021. The results for the three and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021. The Condensed Consolidated Balance Sheet as of December 31, 2020 was derived from our audited financial statements included in our Annual Report on Form 10-K filed with the SEC on March 25, 2021, but is presented as condensed and does not contain all of the footnote disclosures from the annual financial statements.

Accounting Standards

Accounting Standards	6 Months Ended
	Jun. 30, 2021
Accounting Changes and Error Corrections [Abstract]
Accounting Standards	Accounting Standards Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), which affects general principles within Topic 740, and is meant to simplify and reduce the cost of accounting for income taxes. It removes certain exceptions to the general principles in Topic 740 and simplifies areas including franchise taxes that are partially based on income, transactions with a government that result in a step up in the tax basis of goodwill, the incremental approach for intraperiod tax allocation, interim period income tax accounting for year-to-date losses that exceed anticipated losses and enacted changes in tax laws in interim periods. The changes are effective for annual periods beginning after December 15, 2020. The adoption of this pronouncement did not have a material impact on our condensed consolidated financial statements or presentation thereof. Also in October 2020, the FASB issued ASU 2020-10, Codification Improvements. The amendments in this update remove references to various FASB Concepts Statements, situates all disclosure guidance in the appropriate disclosure section of the Codification, and makes other improvements and technical corrections to the Codification. The amendments in Sections B and C of this amendment are effective for annual periods beginning after December 15, 2020, for public business entities, with early adoption permitted. The adoption of this pronouncement did not have a material impact on our condensed consolidated financial statements or presentation thereof. Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments, which introduced an expected credit loss methodology for the measurement and recognition of credit losses on most financial instruments, including trade receivables and off-balance sheet credit exposure. Under this guidance, an entity is required to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. This ASU also requires disclosure of information regarding how a company developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes. The guidance is effective for smaller reporting companies on January 1, 2023 with early adoption permitted. The adoption of this standard will be through a cumulative-effect adjustment to retained earnings as of the effective date. Based on our historical experience, the Company does not expect that this pronouncement will have a significant impact in its financial statements or on the estimate of the allowance for doubtful accounts. The FASB has issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting in March 2020. This new guidance provides optional expedients for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform, on financial reporting. The risk of termination of the London Interbank Offered Rate (LIBOR), has caused regulators to undertake reference rate reform initiatives to identify alternative reference rates that are more observable or transaction based that are less susceptible to manipulation. ASU 2020-04 is effective between March 12, 2020 and December 31, 2022. In addition, in January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope. The amendments in this update refine the scope for certain optional expedients and exceptions for contract modifications and hedge accounting to apply to derivative contracts and certain hedging relationships affected by the discounting transition. The amendments in this update are effective for all entities as of March 12, 2020 through December 31, 2022. The Company is currently evaluating the impact of adopting the reference rate reform guidance (both ASU 2020-04 and ASU 2021-01) on its condensed consolidated financial statements. Management has identified that its credit agreement utilizes LIBOR as a benchmark rate. Management will continue to evaluate the impact of adopting reference rate reform as the LIBOR benchmark rate within the credit agreement is phased out. In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity and amends the scope guidance for contracts in an entity's own equity. The ASU addresses how convertible instruments are accounted for in the calculation of diluted earnings per share by using the if-converted method. The guidance is effective for all entities for fiscal years beginning after March 31, 2024, albeit early adoption is permitted no earlier than fiscal years beginning after December 15, 2020. Management is currently assessing the impact of this pronouncement on its condensed consolidated financial statements.

Accounts Receivable and Allowan

Accounts Receivable and Allowance for Doubtful Accounts	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable and the allowance for doubtful accounts are comprised of the following: (in thousands) June 30, 2021 December 31, 2020 Accounts receivable - trade $ 94,881 $ 86,033 Allowance for doubtful accounts (266) (266) Accounts receivable, net $ 94,615 $ 85,767

Contract Assets and Liabilities

Contract Assets and Liabilities	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Contract Assets and Liabilities	Contract Assets and Liabilities The Company classifies contract assets and liabilities that may be settled beyond one year from the balance sheet date as current, consistent with the length of time of the Company’s project operating cycle. Contract assets include costs in excess of billings and estimated earnings and amounts due under retainage provisions. The components of the contract asset balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract assets Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 $ 6,306 Retainage receivable 32,615 35,204 (2,589) Total contract assets $ 70,815 $ 67,098 $ 3,717 Retainage receivable represents amounts invoiced to customers where payments have been partially withheld, typically 10%, pending the completion of certain milestones, satisfaction of other contractual conditions or the completion of the project. Retainage agreements vary from project to project and balances could be outstanding for several months or years depending on a number of circumstances such as contract-specific terms, project performance and other variables that may arise as the Company makes progress towards completion. Contract assets represent the excess of contract costs and profits (or contract revenue) over the amount of contract billings to date and are classified as a current asset. Contract assets result when either: 1) the appropriate contract revenue amount has been recognized over time in accordance with ASC Topic 606, but a portion of the revenue recorded cannot be currently billed due to the billing terms defined in the contract, or 2) costs are incurred related to certain claims and unapproved change orders. Claims occur when there is a dispute regarding both a change in the scope of work and the price associated with that change. Unapproved change orders occur when a change in the scope of work results in additional work being performed before the parties have agreed on the corresponding change in the contract price. The Company routinely estimates recovery related to claims and unapproved change orders as a form of variable consideration at the most likely amount it expects to receive and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Claims and unapproved change orders are billable upon the agreement and resolution between the contractual parties and after the execution of contractual amendments. Increases in claims and unapproved change orders typically result from costs being incurred against existing or new positions; decreases normally result from resolutions and subsequent billings. The current estimated net realizable value on such claims and unapproved change orders as recorded in contract assets and contract liabilities in the condensed consolidated balance sheets was $40.1 million and $33.6 million as of June 30, 2021 and December 31, 2020, respectively. The Company anticipates that the majority of such amounts will be approved or executed within one year. The resolution of these claims and unapproved change orders may require litigation or other forms of dispute resolution proceedings. Contract liabilities include billings in excess of costs and estimated earnings and provisions for losses. The components of the contract liability balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract liabilities Billings in excess of costs and estimated earnings $ 38,611 $ 46,020 $ (7,409) Provisions for losses 568 628 (60) Total contract liabilities $ 39,179 $ 46,648 $ (7,469) Billings in excess of costs and estimated earnings represent the excess of contract billings to date over the amount of contract costs and profits (or contract revenue) recognized to date. The balance may fluctuate depending on the timing of contract billings and the recognition of contract revenue. Provisions for losses are recognized in the condensed consolidated statements of operations at the uncompleted performance obligation level for the amount of total estimated losses in the period that evidence indicates that the estimated total cost of a performance obligation exceeds its estimated total revenue. The net overbilling position for contracts in process consist of the following: (in thousands) June 30, 2021 December 31, 2020 Revenue earned on uncompleted contracts $ 691,473 $ 752,564 Less: Billings to date (691,884) (766,690) Net overbilling $ (411) $ (14,126) (in thousands) June 30, 2021 December 31, 2020 Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 Billings in excess of costs and estimated earnings (38,611) (46,020) Net overbilling $ (411) $ (14,126) For the three and six months ended June 30, 2021 and 2020, we recorded revisions in our contract estimates for certain GCR and ODR projects. For the three months ended June 30, 2021 and 2020, total net gross profit write-downs were $1.1 million and $2.0 million, respectively. For projects having a material gross profit impact of $0.25 million or more for the three months ended June 30, 2021, this resulted in material gross profit write downs on three GCR segment projects of $1.7 million and one ODR project for $0.3 million. Of the material GCR segment write downs, one project was within the Michigan region for a total of $1.0 million, one project was within the New England region for $0.3 million and one project was within the Southern California region for $0.4 million. Of the material ODR segment write downs, one project was within the Eastern Pennsylvania region for $0.3 million. We also recorded material gross profit write ups of $0.3 million on one GCR segment project in the Florida region and $0.3 million on one ODR segment project in the Michigan region. For the three months ended June 30, 2020, we recorded material revisions in our contract estimates on four GCR projects which resulted in gross profit write downs of $1.5 million. Two of these projects were within the Southern California region for a total of $0.7 million. No project revisions resulting in material gross profit write ups were recorded during the three months ended June 30, 2020. For the six months ended June 30, 2021 and 2020, total net gross profit write-downs were $1.7 million and $3.4 million, respectively. For projects having a material gross profit impact of $0.25 million or more, we recorded gross profit write downs on eight GCR segment projects of $3.5 million and one ODR project for $0.3 million. Of the material GCR segment write downs, two projects were within the Michigan region for a total of $1.2 million, two projects were within the Eastern Pennsylvania region for $1.0 million, two projects were within the Southern California region for $0.8 million, one project was within the New England region for $0.3 million, and one project was within the Mid-Atlantic region for $0.3 million. We also materially wrote down one ODR segment project within the Eastern Pennsylvania region for $0.3 million. We also recorded material GCR segment gross profit write ups of $0.9 million on one GCR segment project in the Michigan region for $0.5 million and one project within the Ohio region for $0.4 million. For the six months ended June 30, 2020, we recorded material gross profit write downs on eight GCR projects and two gross profit write ups on GCR projects, for an aggregate revision of $5.2 million and $1.2 million, respectively. Remaining performance obligations represent the transaction price of firm orders for which work has not been performed and exclude unexercised contract options. The Company’s remaining performance obligations includes projects that have a written award, a letter of intent, a notice to proceed or an agreed upon work order to perform work on mutually accepted terms and conditions. As of June 30, 2021, the aggregate amount of the transaction prices allocated to the remaining performance obligations of the Company's GCR and ODR segment contracts were $378.9 million and $44.2 million, respectively. As of December 31, 2020, the aggregate amount of the transaction prices allocated to the remaining performance obligations of the Company's GCR and ODR segment contracts were $393.5 million and $35.7 million, respectively. We estimate that 44% and 62% of our GCR and ODR segment remaining performance obligations as of June 30, 2021, respectively, will be recognized as revenue during 2021, with the substantial majority of remaining performance obligations to be recognized within 24 months, although the timing of the Company's performance is not always under its control. Additionally, the difference between remaining performance obligations and backlog is due to the exclusion of a portion of the Company’s ODR agreements under certain contract types from the Company’s remaining performance obligations as these contracts can be canceled for convenience at any time by the Company or the customer without considerable cost incurred by the customer. Additional information related to backlog is provided in “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations” of this Quarterly Report on Form 10-Q.

Goodwill and Intangibles

Goodwill and Intangibles	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and Intangibles Goodwill was $6.1 million at both June 30, 2021 and December 31, 2020. The goodwill is associated with the Company's ODR segment. Intangible assets are comprised of the following: (in thousands) Gross Accumulated Net intangible June 30, 2021 (1) Amortized intangible assets: Customer Relationships – ODR $ 4,710 $ (3,312) $ 1,398 Favorable Leasehold Interests (2) 190 (75) 115 Total amortized intangible assets 4,900 (3,387) 1,513 Unamortized intangible assets: Trade Name 9,960 — 9,960 Total unamortized intangible assets 9,960 — 9,960 Total amortized and unamortized assets, excluding goodwill $ 14,860 $ (3,387) $ 11,473 (in thousands) Gross Accumulated Net intangible December 31, 2020 (1) Amortized intangible assets: Customer Relationships – ODR $ 4,710 $ (3,112) $ 1,598 Favorable Leasehold Interests 530 (407) 123 Total amortized intangible assets 5,240 (3,519) 1,721 Unamortized intangible assets: Trade Name 9,960 — 9,960 Total unamortized intangible assets 9,960 — 9,960 Total amortized and unamortized assets, excluding goodwill $ 15,200 $ (3,519) $ 11,681 (1) The Backlog-Construction intangible asset previously shown at December 31, 2020 has been fully amortized. Accordingly, its gross carrying amount of $4.8 million and corresponding accumulated amortization of $4.8 million have been removed from the table. (2) The gross carrying amount and accumulated amortization associated with our Favorable leasehold interests intangible asset was reduced by $0.3 million due to the lease termination of our Western Pennsylvania office associated with the intangible asset. The definite-lived intangible assets are amortized over the period the Company expects to receive the related economic benefit, which for customer relationships is based upon estimated future net cash inflows. The Company has previously determined that its trade name has an indefinite useful life. The Limbach trade name has been in existence since the Company’s founding in 1901 and therefore is an established brand within the industry. Total amortization expense for these amortizable intangible assets was $0.1 million and $0.2 million for the three and six months ended June 30, 2021, respectively, and $0.3 million and $0.4 million for the three and six months ended June 30, 2020, respectively. The Company did not recognize any impairment charges on its goodwill or intangible assets for the three and six months ended June 30, 2021 or 2020.

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt Long-term debt consists of the following obligations as of: (in thousands) June 30, 2021 December 31, 2020 2019 Refinancing Term Loan - term loan payable in quarterly installments of principal, (commencing in September 2020) plus interest through April 2022 $ — $ 39,000 2019 Refinancing Revolving Credit Facility — — Wintrust Term Loan - term loan payable in quarterly installments of principal, (commencing in March 2021) plus interest through February 2026 28,000 — Wintrust Revolving Loan — — Finance leases – collateralized by vehicles, payable in monthly installments of principal, plus interest ranging from 4.70% to 6.45% through 2025 5,476 6,459 Total debt 33,476 45,459 Less - Current portion of long-term debt (8,454) (6,536) Less - Unamortized discount and debt issuance costs (301) (2,410) Long-term debt $ 24,721 $ 36,513 The Company refinanced its 2019 Refinancing Term Loan and 2019 Refinancing Revolving Credit Facility on February 24, 2021, described below and therefore had no amounts outstanding under these agreements at June 30, 2021. Accordingly, the Company recognized a loss on the early debt extinguishment related to the refinancing of $2.0 million on the refinancing date. This loss consisted of the write-off of $2.6 million of debt issuance and debt discount costs, the reversal of the $2.0 million CB warrants liability due to the warrants being cancelled on the refinancing date and the prepayment penalty and other extinguishment costs of $1.4 million. 2019 Refinancing Agreement On April 12, 2019 (the “Refinancing Closing Date”), Limbach Facility Services LLC (“LFS”) entered into a financing agreement (the “2019 Refinancing Agreement”) with the lenders thereto and Cortland Capital Market Services LLC, as collateral agent and administrative agent and CB Agent Services LLC, as origination agent (“CB”). The 2019 Refinancing Agreement consisted of (i) a $40.0 million term loan (the “2019 Refinancing Term Loan”) and (ii) a new $25.0 million multi-draw delayed draw term loan (the “2019 Delayed Draw Term Loan” and, collectively with the 2019 Refinancing Term Loan, the “2019 Term Loans”). Proceeds from the 2019 Refinancing Term Loan were used to repay the then existing Credit Agreement, to pay related fees and expenses thereof and to fund working capital of the 2019 Refinancing Borrowers (defined below). Management intended for proceeds of the 2019 Delayed Draw Term Loan to be used to fund permitted acquisitions under the 2019 Refinancing Agreement and related fees and expenses in connection therewith. LFS and each of its subsidiaries were borrowers (the “2019 Refinancing Borrowers”) under the 2019 Refinancing Agreement. In addition, the 2019 Refinancing Agreement was guaranteed by the Company and LHLLC (each, a “2019 Refinancing Guarantor”, and together with the 2019 Refinancing Borrowers, the “Loan Parties”). The 2019 Refinancing Agreement was secured by a first-priority lien on the real property of the Loan Parties and a second-priority lien on substantially all other assets of the Loan Parties, behind the 2019 ABL Credit Agreement (as defined below). The respective lien priorities of the 2019 Refinancing Agreement and the 2019 ABL Credit Agreement were governed by an intercreditor agreement. 2019 Refinancing Agreement - Interest Rates and Fees The interest rate on borrowings under the 2019 Refinancing Agreement was, at the 2019 Refinancing Borrowers’ option, either LIBOR (with a 2.00% floor) plus 11.00% or a base rate (with a 3.00% minimum) plus 10.00%. At February 24, 2021 (the 2021 refinancing date) and June 30, 2020, the interest rate in effect on the 2019 Refinancing Term Loan was 13.00%. 2019 Refinancing Agreement - Other Terms and Conditions The 2019 Refinancing Agreement was set to mature on April 12, 2022, subject to certain adjustment. Required amortization was $1.0 million per quarter and commenced with the fiscal quarter ending September 30, 2020. There was an unused line fee of 2.0% per annum on the undrawn portion of the 2019 Delayed Draw Term Loan, and there was a make-whole premium on prepayments made prior to the 19-month anniversary of the Refinancing Closing Date. This make-whole provision guaranteed that the Company would pay no less than 18 months’ applicable interest to the lenders under the 2019 Refinancing Agreement. The 2019 Refinancing Agreement contained representations and warranties, and covenants which were customary for debt facilities of this type. Unless the Required Lenders (as defined in the 2019 Refinancing Agreement) otherwise consented in writing, the covenants limited the ability of the Company and its restricted subsidiaries to, among other things, (i) incur additional indebtedness or issue preferred stock, (ii) pay dividends or make distributions to the Company’s stockholders, (iii) purchase or redeem the Company’s equity interests, (iv) make investments, (v) create liens on their assets, (vi) enter into transactions with the Company’s affiliates, (vii) sell assets and (viii) merge or consolidate with, or dispose of substantially all of the Company’s assets to, other companies. In addition, the 2019 Refinancing Agreement included customary events of default and other provisions that could require all amounts due thereunder to become immediately due and payable, either automatically or at the option of the lenders, if the Company failed to comply with the terms of the 2019 Refinancing Agreement or if other customary events occur. Furthermore, the 2019 Refinancing Agreement also contained two financial maintenance covenants for the 2019 Refinancing Term Loan, including a requirement to have sufficient collateral coverage of the aggregate outstanding principal amount of the 2019 Term Loans and as of the last day of each month for the total leverage ratio of the Company and its subsidiaries (the “Total Leverage Ratio”) not to exceed an amount beginning at 4.25 to 1.00 through June 30, 2019, and stepping down to 2.00 to 1.00 effective July 1, 2021. From July 1, 2019 through September 30, 2019, the Total Leverage Ratio may not exceed 4.00 to 1.00. In addition, the parties to the 2019 Refinancing Agreement entered into an amendment which, among other changes, revised the maximum permitted Total Leverage Ratio, starting at 3.30 to 1.00 on October 1, 2019 with a peak ratio of 4.25 during March 2020 along with varying monthly rates culminating in the lowest Total Leverage Ratio of 2.00 to 1.00 on April 1, 2021 through the term of such agreement. The 2019 Refinancing Agreement contained a post-closing covenant requiring the remediation of the Company’s material weakness, as described in Item 9A of its 2018 Annual Report on Form 10-K, no later than December 31, 2020 and provision for updates as to the progress of such remediation, provided that, if such remediation was not completed on or prior to December 31, 2019, (x) the Company would be required to pay the post-closing fee pursuant to the terms of the Origination Agent Fee Letter (as defined in the 2019 Refinancing Agreement) and (y) the applicable margin shall be increased by 1.00% per annum for the period from January 1, 2020 until the date at which the material weakness was no longer disclosed or required to be disclosed in the Company’s SEC filings or audited financial statements of the Company or related auditor’s reports. In connection with the 2019 Refinancing Amendment Number One and Waiver, dated November 14, 2019, the parties amended certain provisions of the 2019 Refinancing Agreement, including, among other changes to: (i) require, commencing October 1, 2019, a 3.00% increase in the interest rate on borrowings under the 2019 Refinancing Agreement; (ii) require the approval of CB and, generally, the lenders representing at least 50.1% of the aggregate undrawn term loan commitment or unpaid principal amount of the 2019 Term Loans, prior to effecting any permitted acquisition; (iii) revise the maximum permitted Total Leverage Ratio, starting at 3.30 to 1.00 on October 1, 2019 with a peak ratio of 4.25 during March 2020 along with varying monthly rates culminating in the lowest Total Leverage Ratio of 2.00 to 1.00 on April 1, 2021 and thereafter through the term of the 2019 Refinancing Agreement; and (iv) require the liquidity of the loan parties, which is generally calculated by adding (a) unrestricted cash on hand of the Loan Parties maintained in deposit accounts subject to control agreements granting control to the collateral agent for the 2019 ABL Credit Agreement, to (b) the difference between (1) the lesser of (x) $15 million, as adjusted from time to time, and (y) 75% of certain customer accounts resulting from the sale of goods or services in the ordinary course of business minus certain reserves established by the administrative agent and (2) the sum of (x) the outstanding principal balance of all revolving loans under the 2019 ABL Credit Agreement plus (y) the aggregate undrawn available amount of all letters of credit then outstanding plus the amount of any obligations that arise from any draw against any letter of credit that have not been reimbursed by the borrowers or funded with a revolving loan under the 2019 ABL Credit Agreement (the “Loan Parties Liquidity”), as of the last day of any fiscal month ending on or after November 30, 2019, of at least $10,000,000. As a condition to executing the 2019 Refinancing Amendment Number One and Waiver, the loan parties were required to pay a non-refundable waiver fee of $400,000 and a non-refundable amendment fee of $1,000,000 (the “PIK First Amendment Fee”, which shall be paid in kind by adding the PIK First Amendment Fee to the outstanding principal amount of the 2019 Refinancing Term Loan as additional principal obligations thereunder on and as of the effective date 2019 Refinancing Amendment Number One and Waiver). During December 2020, the Company was not in compliance with the collateral coverage debt covenant as defined by the 2019 Term Loan financing agreement. The Company was required to maintain at all times a Collateral Coverage Amount (as defined in the 2019 Refinancing Term Loan financing agreement) equal to or greater than the aggregate outstanding principal amount of the 2019 Term Loans. The Company calculated its Collateral Coverage amount at $37.9 million as of December 31, 2020, the aggregate outstanding principal amount of Term Loans was $39.0 million as of that same date for an excess of debt over collateral of $1.1 million. On February 1, 2021, the Company, LFS and LHLLC entered into a Waiver - Collateral Coverage Amount (December 2020) ("December 2020 Waiver") with the lenders party thereto and Cortland Capital Market Services LLC as collateral agent and administrative agent. The December 2020 Waiver included a waiver of the Company's compliance with the Collateral Coverage Amount for the month ending December 31, 2020. The lender waived the event of default arising from this noncompliance as of December 31, 2020, while reserving its rights with respect to covenant compliance in future months. The 2019 Refinancing Term Loan was paid in full on February 24, 2021 as part of the refinancing transaction. 2019 Refinancing Agreement - CB Warrants In connection with the 2019 Refinancing Agreement, on the Refinancing Closing Date, the Company issued to CB and the other lenders under the 2019 Refinancing Agreement warrants (the “CB Warrants”) to purchase up to a maximum of 263,314 shares of the Company's common stock at an exercise price of $7.63 per share subject to certain adjustments, including for stock dividends, stock splits or reclassifications. The actual number of shares of common stock into which the CB Warrants were exercisable at any given time were equal to: (i) the product of (x) the number of shares equal to 2% of the Company’s issued and outstanding shares of common stock on the Refinancing Closing Date on a fully diluted basis and (y) the percentage of the total 2019 Delayed Draw Term Loan made as of the exercise date, minus (ii) the number of shares previously issued under the CB Warrants. As of the Refinancing Closing Date through February 24, 2021, no amounts had been drawn on the 2019 Delayed Draw Term Loan, so no portion of the CB Warrants were exercisable. The CB Warrants were to be exercised for cash or on a “cashless basis,” subject to certain adjustments, at any time after the 2019 Refinancing Closing Date until the expiration of such warrant at 5:00 p.m., New York time, on the earlier of (i) the five (5) year anniversary of the 2019 Refinancing Closing Date, or (ii) the liquidation of the Company. Accounting for the 2019 Term Loans and CB Warrants The CB Warrants represented a freestanding financial instrument that was classified as a liability because the CB Warrants met the definition of a derivative instrument that does not meet the equity scope exception (i.e., the CB Warrants were not indexed to the entity’s own equity). In addition, the material weakness penalty described above was evaluated as an embedded derivative liability and bifurcated from the 2019 Term Loans as it represented a non-credit related embedded feature that provides for net settlement. Both the CB Warrants liability and the embedded derivative liability were required to be initially and subsequently measured at fair value. The initial fair values of the CB Warrants liability and the embedded derivative liability approximated $0.9 million and $0.4 million, respectively, on the Refinancing Closing Date. The Company estimated these fair values by using the Black-Scholes-Merton option pricing model and a probability-weighted discounted cash flow approach. The CB Warrants liability was included in other long-term liabilities. The Company remeasured the fair value of the CB Warrants liability as of December 31, 2020 and February 24, 2021 prior to the refinancing date and recorded any adjustments as other income (expense). At both February 24, 2021 and December 31, 2020, the CB Warrants liability was $2.0 million. Due to the extinguishment of the CB Warrants on February 24, 2021, there was no liability associated with the CB Warrants recorded as of June 30, 2021. For the six months ended June 30, 2021, the Company recorded other income of $0.1 million to reflect the change in the fair value of the CB Warrants liability. The Company did not record a change in fair value of the warrant liability during the three months ended June 30, 2021 as the CB Warrants liability was extinguished as part of the debt refinancing on February 24, 2021. For the three and six months ended June 30, 2020, the Company recorded other income of $0.1 million and other expense of $0.1 million to reflect the change in the CB Warrants liability. The proceeds for the 2019 Refinancing Term Loan were first allocated to the CB Warrants liability and embedded derivative liability based on their respective fair values with a corresponding amount of $1.3 million recorded as a debt discount to the 2019 Term Loans. In addition, the Company incurred approximately $3.9 million of debt issuance costs, including $1.4 million related to the first amendment, for the 2019 Term Loans that have also been recorded as a debt discount. The combined debt discount from the CB Warrants liability, embedded derivative liability and the debt issuance costs were being amortized into interest expense over the term of the 2019 Term Loans using the effective interest method and were expensed on the refinancing date as a loss on early debt extinguishment. The Company recorded interest expense for the amortization of the CB Warrants liability and embedded derivative debt discounts of $0.1 million for the six months ended June 30, 2021. The Company did not record interest expense for the amortization of the CB Warrants liability and embedded derivative liability debt discounts for the three months ended June 30, 2021 as these debt discounts were extinguished as part of the debt refinancing on February 24, 2021. The Company recorded interest expense for the amortization of the CB Warrants liability and embedded derivative debt discounts of $0.1 million and $0.2 million for the three and six months ended June 30, 2020, respectively. In addition to the amortization of the debt discounts into interest expense, the Company recorded $0.1 million of interest expense for the amortization of debt issuance costs related to the 2019 Refinancing Term Loan for the six months ended June 30, 2021. The Company did not record any interest expense for the amortization of debt issuance costs for the three months ended June 30, 2021 as the debt issuance costs were extinguished as part of the debt refinancing on February 24, 2021. For the three and six months ended June 30, 2020, the Company recorded an additional $0.4 million and $0.7 million of interest expense, respectively, for the amortization of the debt issuance costs related to the 2019 Refinancing Term Loan. 2019 ABL Credit Agreement On the Refinancing Closing Date, LFS also entered into a financing agreement with the lenders thereto and Citizens Bank, N.A., as collateral agent, administrative agent and origination agent (the “2019 ABL Credit Agreement” and, together with the 2019 Refinancing Agreement, the “Refinancing Agreements”). The 2019 ABL Credit Agreement consisted of a $15.0 million revolving credit facility (the “2019 Revolving Credit Facility”). Proceeds of the 2019 Revolving Credit Facility were to be used for general corporate purposes. On the Refinancing Closing Date, the Company had nothing drawn on the ABL Credit Agreement and $14.0 million of available borrowing capacity thereunder (net of a $1.0 million reserve imposed by the lender). The 2019 Refinancing Borrowers and 2019 Refinancing Guarantors under the 2019 ABL Credit Agreement were the same as under the 2019 Refinancing Agreement. The 2019 ABL Credit Agreement was secured by a second-priority lien on the real property of the Loan Parties (behind the 2019 Refinancing Agreement) and a first-priority lien on substantially all other assets of the Loan Parties. 2019 ABL Credit Agreement - Interest Rates and Fees The interest rate on borrowings under the 2019 ABL Credit Agreement was, at the 2019 Refinancing Borrowers’ option, either LIBOR (with a 2.0% floor) plus an applicable margin ranging from 3.00% to 3.50% or a base rate (with a 3.0% minimum) plus an applicable margin ranging from 2.00% to 2.50%. At February 24, 2021 (the 2021 refinancing date) and June 30, 2020, the interest rate in effect on the 2019 ABL Credit Agreement was 5.25%. 2019 ABL Credit Agreement - Other Terms and Conditions The 2019 ABL Credit Agreement was set to mature on April 12, 2022. There was also an unused line fee ranging from 0.250% to 0.375% per annum on undrawn amounts. The 2019 ABL Credit Agreement contained representations and warranties, and covenants which are customary for debt facilities of this type. Unless the Required Lenders otherwise consented in writing, the covenants limited the ability of the Company and its restricted subsidiaries to, among other things, generally, to (i) incur additional indebtedness or issue preferred stock, (ii) pay dividends or make distributions to the Company’s stockholders, (iii) purchase or redeem the Company’s equity interests, (iv) make investments, (v) create liens on their assets, (vi) enter into transactions with the Company’s affiliates, (vii) sell assets other than in the ordinary course of business or another permitted disposition of assets and (viii) merge or consolidate with, or dispose of substantially all of the Company’s assets to, other companies. The 2019 ABL Credit Agreement included customary events of default and other provisions that could require all amounts due thereunder to become immediately due and payable, either automatically or at the option of the lenders, if the Company failed to comply with the terms of the 2019 ABL Credit Agreement or if other customary events occur. The 2019 ABL Credit Agreement also contained a financial maintenance covenant for the 2019 Revolving Credit Facility, which is a requirement for the Total Leverage Ratio of the Company and its subsidiaries not to exceed an amount beginning at 4.00 to 1.00 through September 30, 2019, and stepping down to 1.75 to 1.00 effective July 1, 2021. In addition, the parties to the 2019 ABL Credit Agreement entered into an amendment which, among other changes revises the maximum permitted Total Leverage Ratio, starting at 3.30 to 1.00 on October 1, 2019 with a peak ratio of 4.25 during March 2020 along with varying monthly rates culminating in the lowest Total Leverage Ratio of 2.00 to 1.00 on April 1, 2021 through the term of such agreement. In connection with the 2019 ABL Credit Amendment Number One and Waiver, the parties amended certain provisions of the 2019 ABL Credit Agreement, including, among other changes to (i) require the approval of the origination agent and, generally, the lenders representing at least 50.1% of the aggregate undrawn revolving loan commitment or unpaid principal amount of the 2019 Term Loans, prior to effecting any permitted acquisition; (ii) revise the maximum permitted Total Leverage Ratio, starting at 3.30 to 1.00 on October 1, 2019 with a peak ratio of 4.25 during March 2020 along with varying monthly rates culminating in the lowest Total Leverage Ratio of 2.00 to 1.00 on April 1, 2021 through the term of the 2019 ABL Credit Agreement; and (iii) require the Loan Parties Liquidity as of the last day of any fiscal month ending on or after November 30, 2019, of at least $10,000,000, as described above in the Amendment Number One to 2019 Refinancing Agreement and Waiver. As a condition to executing the 2019 ABL Credit Amendment Number One and Waiver, the loan parties were required to pay a non-refundable waiver fee of $7,500. As noted above in the section titled: 2019 Refinancing Agreement - Other Terms and Conditions, the Company was subject to cross-default under our 2019 Revolving Credit Facility as a result of our failure to satisfy the Collateral Coverage Amount as defined in the 2019 Term Loan financing agreement, which required the company to obtain a waiver. Accordingly, on February 1, 2021, the Company, LFS and LHLLC entered into a Waiver - Collateral Coverage Amount (December 2020) (“December 2020 Waiver”) with the lenders party thereto and Citizens Bank, N.A., as collateral agent and administrative agent. The December 2020 Waiver included a waiver of the Company's compliance with the Collateral Coverage Amount for the month ending December 31, 2020. The lender has waived the event of default arising from this noncompliance as of December 31, 2020, while reserving its rights with respect to covenant compliance in future months. At February 24, 2021 (the 2021 refinancing date) and December 31, 2020, the Company had irrevocable letters of credit in the amount of $3.4 million with its lender to secure obligations under its self-insurance program. Accounting for the 2019 ABL Credit Agreement The Company incurred approximately $0.9 million of debt issuance costs for the 2019 ABL Credit Agreement that had been recorded as a non-current deferred asset. The deferred asset was amortized into interest expense over the term of the 2019 Term ABL Credit Agreement using the effective interest method and then expensed on the February 24, 2021 refinancing date as a loss on early debt extinguishment. The Company recorded $0.1 million of interest expense for the amortization of debt issuance costs for the six months ended June 30, 2021. The Company did not record any interest expense for the amortization of debt issuance costs for the three months ended June 30, 2021 as the debt issuance costs were extinguished as part of the debt refinancing on February 24, 2021. For both the three and six months ended June 30, 2020, the Company recorded $0.1 million of interest expense for the amortization of debt issuance costs. Wintrust Term and Revolving Loans On February 24, 2021, LFS, LHLLC and the direct and indirect subsidiaries of LFS from time to time included as parties to the agreement (the “Wintrust Guarantors”) entered into a Credit Agreement (the “Credit Agreement”) by and among the LFS, LHLLC, Wintrust Guarantors, the lenders party thereto from time to time, Wheaton Bank & Trust Company, N.A., a subsidiary of Wintrust Financial Corporation (collectively, “Wintrust”), as administrative agent and L/C issuer, Bank of the West as documentation agent, M&T Bank as syndication agent, and Wintrust as lead arranger and sole book runner. In accordance with the terms of the Credit Agreement, Lenders provide to LFS (i) a $30.0 million senior secured term loan (the “Wintrust Term Loan”); and (ii) a $25.0 million senior secured revolving credit facility with a $5.0 million sublimit for the issuance of letters of credit (the “Wintrust Revolving Loan” and, together with the Wintrust Term Loan, the “Wintrust Loans”). Proceeds of the Wintrust Loans were used to refinance certain existing indebtedness, finance working capital and other general corporate purposes and fund certain fees and expenses associated with the closing of the Wintrust Loans. The Wintrust Revolving Loan bears interest, at the LFS’s option, at either LIBOR (with a 0.25% floor) plus 3.5% or a base rate (with a 3.0% floor) plus 0.50%, subject to a 50 basis point step-down based on the ratio between the senior debt of the Company and its subsidiaries to the EBITDA (earnings before interest, income taxes, depreciation and amortization) of the LFS and its subsidiaries for the most recently ended four fiscal quarters (the “Senior Leverage Ratio”). The Wintrust Term Loan bears interest, at LFS’s option, at either LIBOR (with a 0.25% floor) plus 4.0% or a base rate (with a 3.0% floor) plus 1.00%, subject to a 50 (for LIBOR) or 75 (for base rate) basis point step-down based on the Senior Leverage Ratio. LFS is required to make principal payments on the Wintrust Term Loan in $0.5 million installments on the last business day of each month commencing on March 31, 2021 with a final payment of all principal and interest not sooner paid on the Wintrust Term Loan due and payable on February 24, 2026. The Wintrust Revolving Loan will mature and become due and payable by LFS on February 24, 2026. The Wintrust Loans are secured by (i) a valid, perfected and enforceable lien of the administrative agent on the ownership interests held by each of LFS and Wintrust Guarantors in their respective subsidiaries; and (ii) a valid, perfected and enforceable lien of the administrative agent on each of LFS and Wintrust Guarantors’ personal property, fixtures and real estate, subject to certain exceptions and limitations. Additionally, the re-payment of the Wintrust Loans shall be jointly and severally guaranteed by each Wintrust Guarantor. The Credit Agreement contains representations and warranties, covenants and events of default that are customary for facilities of this type, as more particularly described in the Credit Agreement. The Wintrust Loans also contain three financial maintenance covenants, including (i) a requirement to have as of the last day of each quarter for the senior leverage ratio of the Company and its subsidiaries not to exceed an amount beginning at 2.25 to 1.00 through December 31, 2021, and stepping down to 2.00 to 1.00 at all times thereafter, (ii) a fixed charge coverage ratio of not less than 1.20 to 1.00 as of the last day of each fiscal quarter commencing with the fiscal quarter ending March 31, 2021, and (iii) no unfinanced capital expenditures, except for unfinanced capital expenditures in the ordinary course of business not exceeding in the aggregate $4.0 million during any fiscal year; and no default or event of default (as defined by the agreement) has occurred and is continuing, 50% of any portion of this annual limit, if not expended in the fiscal year for which it is permitted, may be carried over for expenditure in the next following fiscal year as stipulated by the agreement. LFS and its affiliates maintain various commercial and service relationships with certain members of the syndicate and their affiliates in the ordinary course of business. As of June 30, 2021, the Company was in compliance with all financial maintenance covenants as required by the Wintrust Loans. The following is a summary of the additional margin and commitment fees payable on the available Wintrust Term Loan and Wintrust Revolving Loan credit commitment: Level Senior Leverage Ratio Additional Margin for Additional Margin for Additional Margin for Eurodollar Term loans Additional Margin for Eurodollar Revolving loans Commitment Fee I Greater than 1.00 to 1.00 1.00 % 0.50 % 4.00 % 3.50 % 0.25 % II Less than or equal to 1.00 to 1.00 0.25 % — % 3.50 % 3.00 % 0.25 % At June 30, 2021, the interest rate in effect on the Wintrust Term Loan was 4.25% and the interest rate in effect on the Wintrust Revolving Loan was 3.75%.

Equity

Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Equity	Equity The Company’s second amended and restated certificate of incorporation currently authorizes the issuance of 100,000,000 shares of common stock, par value $0.0001, and 1,000,000 shares of preferred stock, par value $0.0001. The Public, Private and $15 Exercise Price Sponsor warrants were issued in conjunction with the Company's initial public offering and the Merger and Additional Merger warrants were issued in conjunction with the business combination with LHLLC. June 30, 2021 December 31, 2020 Public Warrants (1)(5) 2,140,219 2,300,000 Private Warrants (1)(5) 99,000 99,000 $15 Exercise Price Sponsor Warrants (2)(5) 600,000 600,000 Merger Warrants (3)(6) 629,643 631,119 Additional Merger Warrants (4)(6) 935,068 946,680 Total 4,403,930 4,576,799 (1) Exercisable for one-half of one share of common stock at an exercise price of $5.75 per half share ($11.50 per whole share) (2) Exercisable for one share of common stock at an exercise price of $15.00 per share (3) Exercisable for one share of common share at an exercise price of $12.50 per share (4) Exercisable for one share of common stock at an exercise price of $11.50 per share (5) Issued under a warrant agreement dated July 15, 2014, between Continental Stock Transfer and Trust Company, as warrant agent, and the Company (6) Issued to the sellers of LHLLC Subsequent to June 30, 2021, on July 20, 2021, the Public Warrants, Private Warrants, and Additional Merger Warrants expired by their terms. On May 24, 2020 the Board of Directors approved further amendments to the Company's amended and restated Omnibus Incentive Plan to increase the number of shares of the Company's common stock that may be issued pursuant to awards by 500,000, for a total of 1,650,000 shares, and extend the term of the plan so that it will expire on the tenth anniversary of the date the stockholders approve the Amended Incentive Plan. The amendments were approved by the Company's stockholders at the Annual Meeting held on July 14, 2020. On March 9, 2021, the Board of Directors approved further amendments to the Company's amended and restated Omnibus Incentive Plan to increase the number of shares of the Company's common stock that may be issued pursuant to awards by 600,000, for a total of 2,250,000 shares, and extend the term of the plan so that it will expire on the tenth anniversary of the date the stockholders approve the Amended Incentive Plan. The amendments were approved by the Company's stockholders at the Annual Meeting held on June 16, 2021. See Note 17 - Management Incentive Plans for RSUs granted, vested, forfeited and remaining unvested. Upon approval of the Company's stockholders on May 30, 2019, the Company adopted the Limbach Holdings, Inc. 2019 Employee Stock Purchase Plan (“the ESPP”). On January 1, 2020, the ESPP went into effect. The ESPP enables eligible employees, as defined by the ESPP, the right to purchase the Company's common stock through payroll deductions during consecutive subscription periods at a purchase price of not less than 85% of the fair market value of a common share at the end of each offering period. Annual purchases by participants are limited to the number of whole shares that can be purchased by an amount equal to ten percent of the participant's compensation or $5,000, whichever is less. Each offering period of the ESPP lasts six months, commencing on January 1 and July 1 of each year. The amounts collected from participants during a subscription period are used on the exercise date to purchase full shares of common stock. Participants may withdraw from an offering before the exercise date and obtain a refund of amounts withheld through payroll deductions. Compensation cost, representing the 15% discount applied to the fair market value of common stock, is recognized on a straight-line basis over the six-month vesting period during which employees perform related services. Under the ESPP, 500,000 shares are authorized to be issued. In July 2020 and January 2021, the Company issued 30,825 and 8,928 shares of its common stock, respectively, to participants in the ESPP who contributed to the plan through the June 30, 2020 and December 31, 2020 offering periods, respectively. On February 10, 2021 the Company entered into an underwriting agreement (“Underwriting Agreement”) with Lake Street Capital Markets, LLC (“Underwriter”) relating to an underwritten public offering (the “Offering”). On February 12, 2021 the Company sold to the Underwriter 1,783,500 shares of its Common Stock. The Underwriting Agreement provided for purchase and sale of the Shares by the company to the Underwriter at a price of $11.28 per share. The price to the public in the Offering was $12.00 per share. In addition, under the terms of the Underwriting Agreement, the Company granted the Underwriter a 30-day option to purchase up to an additional 267,525 shares of Common Stock to cover over-allotments, if any, on the same terms and conditions. The net proceeds to the Company from the Offering after deducting the underwriting discounts and commissions were approximately $19.8 million. On February 18, 2021, the Company received approximately $3.0 million of net proceeds for the sale of 267,525 shares in connection with the exercise of the over-allotment option.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company measures the fair value of financial assets and liabilities in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures, which defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to measurements involving significant unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows: • Level 1 — inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that are accessible at the measurement date; • Level 2 — inputs other than quoted prices included in Level 1 that are observable for the asset or liability either directly or indirectly such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities; and • Level 3 — unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Diluted EPS assumes the dilutive effect of outstanding common stock warrants and RSUs using the treasury stock method. Three months ended June 30, Six months ended June 30, (in thousands, except per share amounts) 2021 2020 2021 2020 EPS numerator: Net income (loss) $ 732 $ 2,947 $ (1,550) $ 2,895 EPS denominator: Weighted average shares outstanding – basic 10,252 7,846 9,738 7,822 Impact of dilutive securities 217 59 — 56 Weighted average shares outstanding – diluted 10,469 7,905 9,738 7,878 EPS: Basic $ 0.07 $ 0.38 $ (0.16) $ 0.37 Diluted $ 0.07 $ 0.37 $ (0.16) $ 0.37 The following table summarizes the securities that were antidilutive or out-of-the-money, and therefore, were not included in the computations of diluted loss per common share: Three months ended June 30, Six months ended June 30, 2021 2020 2021 2020 In-the-money warrants — — — — Out-of-the-money warrants (see Note 8) 4,403,930 4,576,799 4,403,930 4,576,799 Service-based RSUs (See Note 17) 334 463 142,120 1,255 Performance and market-based RSUs (1) 13,929 9,674 79,971 — Employee Stock Purchase Plan — — 4,778 — Total 4,418,193 4,586,936 4,630,799 4,578,054 (1) For the three and six months ended June 30, 2021 and 2020, certain PRSU and MRSU awards were not included in the computation of diluted loss per share because the performance and market conditions were not satisfied during the periods and would not be satisfied if the reporting date was at the end of the contingency period.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is taxed as a C corporation. For interim periods, the provision for income taxes (including federal, state, local and foreign taxes) is calculated based on the estimated annual effective tax rate, adjusted for certain discrete items for the full fiscal year. Cumulative adjustments to the Company's estimate are recorded in the interim period in which a change in the estimated annual effective rate is determined. Each quarter we update our estimate of the annual effective tax rate, and if our estimated tax rate changes, we make a cumulative adjustment. The Company had an effective tax rate of 26.5% and an effective tax benefit rate of 33.2% for the three and six months ended June 30, 2021, respectively. For the three and six months ended June 30, 2020, the Company had an income tax rate of 27.4% and 14.1%, respectively. No valuation allowance was required as of June 30, 2021 or December 31, 2020. The Company had previously recorded a liability for unrecognized tax benefits (“UTB”) related to tax positions taken on its various income tax returns in open tax periods. If recognized, a portion of unrecognized tax benefits would favorably impact the effective tax rate that is reported in future periods. The Company filed to change an improper tax method of accounting in the fourth quarter of 2020 related to the UTB that affords the Company IRS audit protection in past periods. Therefore, the total unrecognized tax benefits were reduced in the fourth quarter of 2020. The following is a reconciliation of the beginning and ending unrecognized tax benefits: June 30, 2021 December 31, 2020 Balance at beginning of period $ — $ 1,130 Gross increases in prior period tax positions — — Gross increases in current period tax positions — — Decreases related to prior year tax positions — (1,130) Balance at end of period $ — $ —

Operating Segments

Operating Segments	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Operating Segments	Operating Segments The Company determined its operating segments on the same basis that it assesses performance and makes operating decisions. The Company manages and measures the performance of its business in two distinct operating segments. As of January 1, 2021, the Company renamed its existing two reportable segments to reflect its two distinct approaches to our customer base and to better align with our owner direct strategy. The previously named Construction Segment is now known as General Contractor Relationships (“GCR”); the previously named Service Segment is now known as Owner Direct Relationships (“ODR”). These segments are reflective of how the Company’s Chief Operating Decision Maker (“CODM”) reviews operating results for the purposes of allocating resources and assessing performance. The Company's CODM is comprised of its Chief Executive Officer, Chief Financial Officer and Chief Operating Officer. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. The CODM evaluates performance based on income from operations of the respective segments after the allocation of corporate office operating expenses. In accordance with ASC Topic 280 – Segment Reporting, the Company has elected to aggregate all of the construction activity into one GCR reportable segment and all of the service branches into one ODR reportable segment. All transactions between segments are eliminated in consolidation. Our corporate department provides general and administrative support services to our two operating segments. The CODM allocates costs between segments for selling, general and administrative and depreciation expense. All of the Company’s identifiable assets are located in the United States, which is where the Company is domiciled. Interest expense is not allocated to segments because of the corporate management of debt service including interest. Condensed consolidated segment information for the three months ended June 30, 2021 and 2020 is as follows: Three months ended June 30, (in thousands) 2021 2020 Statement of Operations Data: Revenue: GCR $ 87,550 $ 105,937 ODR 33,469 29,248 Total revenue 121,019 135,185 Gross profit: GCR 8,885 12,213 ODR 9,805 8,122 Total gross profit 18,690 20,335 Selling, general and administrative: GCR 9,070 8,024 ODR 7,526 5,588 Corporate 636 140 Total selling, general and administrative 17,232 13,752 Amortization of intangibles 104 274 Operating income $ 1,354 $ 6,309 Operating income for reportable segments $ 1,354 $ 6,309 Less unallocated amounts: Interest expense, net (452) (2,137) Gain (loss) on disposition of property and equipment 94 (13) Loss on change in fair value of warrant liability — (102) Total unallocated amounts (358) (2,252) Income before income taxes $ 996 $ 4,057 Other Data: Depreciation and amortization: GCR $ 1,020 $ 1,032 ODR 345 330 Corporate 104 274 Total other data $ 1,469 $ 1,636 Summarized segment information is as follows: Three months ended June 30, 2021 Three months ended June 30, 2020 (in thousands) GCR ODR Total GCR ODR Total Revenue $ 87,550 $ 33,469 $ 121,019 $ 105,937 $ 29,248 $ 135,185 Gross Profit 8,885 9,805 18,690 12,213 8,122 20,335 Selling, general and administrative 9,070 7,526 16,596 8,024 5,588 13,612 EBIT $ (185) $ 2,279 $ 2,094 $ 4,189 $ 2,534 $ 6,723 Reconciliation of segment gross profit to income before income taxes: Three months ended June 30, (in thousands) 2021 2020 Total gross profit from reportable segments $ 18,690 $ 20,335 Selling, general and administrative (17,232) (13,752) Amortization of intangibles (104) (274) Total other expenses (358) (2,252) Income before income taxes $ 996 $ 4,057 Condensed consolidated segment information for the six months ended June 30, 2021 and 2020 is as follows: Six months ended June 30, (in thousands) 2021 2020 Statement of Operations Data: Revenue: GCR $ 172,354 $ 215,423 ODR 62,009 58,534 Total revenue 234,363 273,957 Gross profit: GCR 18,280 23,195 ODR 17,639 15,364 Total gross profit 35,919 38,559 Selling, general and administrative: GCR 18,184 18,200 ODR 14,880 11,917 Corporate 1,313 435 Total selling, general and administrative 34,377 30,552 Amortization of intangibles 208 417 Operating income $ 1,334 $ 7,590 Operating income for reportable segments $ 1,334 $ 7,590 Less unallocated amounts: Interest expense, net (1,716) (4,295) Gain on disposition of property and equipment 8 17 Loss on early debt extinguishment (1,961) — Gain on change in fair value of warrant liability 14 59 Total unallocated amounts (3,655) (4,219) (Loss) income before income taxes $ (2,321) $ 3,371 Other Data: Depreciation and amortization: GCR $ 2,056 $ 2,062 ODR 700 661 Corporate 208 417 Total other data $ 2,964 $ 3,140 Summarized segment information is as follows: Six months ended June 30, 2021 Six months ended June 30, 2020 (in thousands) GCR ODR Total GCR ODR Total Revenue $ 172,354 $ 62,009 $ 234,363 $ 215,423 $ 58,534 $ 273,957 Gross Profit 18,280 17,639 35,919 23,195 15,364 38,559 Selling, general and administrative 18,184 14,880 33,064 18,200 11,917 30,117 EBIT $ 96 $ 2,759 $ 2,855 $ 4,995 $ 3,447 $ 8,442 Reconciliation of segment gross profit to (loss) income before income taxes: Six months ended June 30, (in thousands) 2021 2020 Total gross profit from reportable segments $ 35,919 $ 38,559 Selling, general and administrative (34,377) (30,552) Amortization of intangibles (208) (417) Total other expenses (3,655) (4,219) (Loss) income before income taxes $ (2,321) $ 3,371

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Leases	Leases The Company leases real estate, trucks and other equipment. The determination of whether an arrangement is, or contains, a lease is performed at the inception of the arrangement. Classification and initial measurement of the right-of-use asset and lease liability are determined at the lease commencement date. The Company elected the short-term lease measurement and recognition exemption; therefore, leases with an initial term of 12 months or less are not recorded on the condensed consolidated balance sheets. The Company's arrangements include certain non-lease components such as common area and other maintenance for leased real estate, as well as mileage, fuel and maintenance costs related to leased vehicles. For all leased asset classes, the Company has elected to not separate non-lease components from lease components and will account for each separate lease component and non-lease component associated with the lease as a single lease component. The Company does not guarantee any residual value in its lease agreements, and there are no material restrictions or covenants imposed by lease arrangements. Real estate leases typically include one or more options to extend the lease. The Company regularly evaluates the renewal options, and when they are reasonably certain of exercise, the Company includes the renewal period in its lease term. For our leased vehicles, the Company uses the interest rate implicit in its leases with the lessor to discount lease payments at the lease commencement date. When the implicit rate is not readily available, as is the case with our real estate leases, the Company uses quoted borrowing rates on our secured debt. The following table summarizes the lease amounts included in our condensed consolidated balance sheets: (in thousands) Classification on the Condensed Consolidated Balance Sheets June 30, 2021 December 31, 2020 Assets Operating Operating lease right-of-use assets (a) $ 16,852 $ 18,751 Finance Property and equipment, net (b) 5,251 6,242 Total lease assets $ 22,103 $ 24,993 Liabilities Current Operating Current operating lease liabilities $ 4,122 $ 3,929 Finance Current portion of long-term debt 2,454 2,536 Noncurrent Operating Long-term operating lease liabilities 13,454 15,459 Finance Long-term debt 3,022 3,923 Total lease liabilities $ 23,052 $ 25,847 (a) Operating lease assets are recorded net of accumulated amortization of $13.9 million at June 30, 2021 and $11.9 million at December 31, 2020. (b) Finance lease assets are recorded net of accumulated amortization of $5.6 million at June 30, 2021 and $5.3 million at December 31, 2020. The following table summarizes the lease costs included in our condensed consolidated statements of operations for the three and six months ended June 30, 2021 and 2020: Three months ended June 30, Six months ended June 30, (in thousands) Classification on the Condensed Consolidated Statement of Operations 2021 2020 2021 2020 Operating lease cost Cost of revenue (a) $ 685 $ 893 $ 1,375 $ 1,777 Operating lease cost Selling, general and administrative (a) 584 376 1,169 757 Finance lease cost Amortization Cost of revenue (b) 652 645 1,327 1,311 Interest Interest expense, net (b) 78 86 164 179 Total lease cost $ 1,999 $ 2,000 $ 4,035 $ 4,024 (a) Operating lease costs recorded in cost of sales includes $0.1 million and $0.2 million of variable lease costs for the three and six months ended June 30, 2021, respectively, and $0.1 million and $0.4 million for the three and six months ended June 30, 2020, respectively. In addition, $0.1 million and $0.2 million of variable leases costs are included in Selling, general and administrative for the three and six months ended June 30, 2021, respectively, and $0.1 million for both the three and six months ended June 30, 2020. These variable costs consist of our proportionate share of operating expenses, real estate taxes and utilities. (b) Finance lease costs recorded in cost of revenue include variable lease costs of $0.7 million and $1.3 million for the three and six months ended June 30, 2021, respectively, and $0.5 million and $1.2 million for the three and six months ended June 30, 2020, respectively. These variable lease costs consist of fuel, maintenance, and sales tax charges. No variable lease costs for finance leases were recorded in selling, general and administrative. Future minimum commitments for finance and operating leases that have non-cancelable lease terms in excess of one year as of June 30, 2021 were as follows: Year ending (in thousands): Finance Operating Remainder of 2021 $ 1,401 $ 2,479 2022 2,404 4,616 2023 1,409 3,516 2024 598 2,917 2025 50 2,409 Thereafter — 4,043 Total minimum lease payments $ 5,862 $ 19,980 Amounts representing interest (386) Present value of net minimum lease payments $ 5,476 The following is a summary of the lease terms and discount rates: June 30, 2021 December 31, 2020 Weighted average lease term (in years): Operating 5.15 5.48 Finance 2.49 2.78 Weighted average discount rate: Operating 4.84 % 4.83 % Finance 5.45 % 5.50 % The following is a summary of other information and supplemental cash flow information related to finance and operating leases: Six months ended June 30, (in thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,456 $ 2,910 Operating cash flows from finance leases 164 179 Financing cash flows from finance leases 1,318 1,285 Right-of-use assets exchanged for lease liabilities: Operating leases $ 156 $ — Finance leases 336 1,050 Right-of-use assets disposed or adjusted modifying operating leases liabilities $ 36 $ 586 Right-of-use assets disposed or adjusted modifying finance leases liabilities $ — $ (64)
Leases	Leases The Company leases real estate, trucks and other equipment. The determination of whether an arrangement is, or contains, a lease is performed at the inception of the arrangement. Classification and initial measurement of the right-of-use asset and lease liability are determined at the lease commencement date. The Company elected the short-term lease measurement and recognition exemption; therefore, leases with an initial term of 12 months or less are not recorded on the condensed consolidated balance sheets. The Company's arrangements include certain non-lease components such as common area and other maintenance for leased real estate, as well as mileage, fuel and maintenance costs related to leased vehicles. For all leased asset classes, the Company has elected to not separate non-lease components from lease components and will account for each separate lease component and non-lease component associated with the lease as a single lease component. The Company does not guarantee any residual value in its lease agreements, and there are no material restrictions or covenants imposed by lease arrangements. Real estate leases typically include one or more options to extend the lease. The Company regularly evaluates the renewal options, and when they are reasonably certain of exercise, the Company includes the renewal period in its lease term. For our leased vehicles, the Company uses the interest rate implicit in its leases with the lessor to discount lease payments at the lease commencement date. When the implicit rate is not readily available, as is the case with our real estate leases, the Company uses quoted borrowing rates on our secured debt. The following table summarizes the lease amounts included in our condensed consolidated balance sheets: (in thousands) Classification on the Condensed Consolidated Balance Sheets June 30, 2021 December 31, 2020 Assets Operating Operating lease right-of-use assets (a) $ 16,852 $ 18,751 Finance Property and equipment, net (b) 5,251 6,242 Total lease assets $ 22,103 $ 24,993 Liabilities Current Operating Current operating lease liabilities $ 4,122 $ 3,929 Finance Current portion of long-term debt 2,454 2,536 Noncurrent Operating Long-term operating lease liabilities 13,454 15,459 Finance Long-term debt 3,022 3,923 Total lease liabilities $ 23,052 $ 25,847 (a) Operating lease assets are recorded net of accumulated amortization of $13.9 million at June 30, 2021 and $11.9 million at December 31, 2020. (b) Finance lease assets are recorded net of accumulated amortization of $5.6 million at June 30, 2021 and $5.3 million at December 31, 2020. The following table summarizes the lease costs included in our condensed consolidated statements of operations for the three and six months ended June 30, 2021 and 2020: Three months ended June 30, Six months ended June 30, (in thousands) Classification on the Condensed Consolidated Statement of Operations 2021 2020 2021 2020 Operating lease cost Cost of revenue (a) $ 685 $ 893 $ 1,375 $ 1,777 Operating lease cost Selling, general and administrative (a) 584 376 1,169 757 Finance lease cost Amortization Cost of revenue (b) 652 645 1,327 1,311 Interest Interest expense, net (b) 78 86 164 179 Total lease cost $ 1,999 $ 2,000 $ 4,035 $ 4,024 (a) Operating lease costs recorded in cost of sales includes $0.1 million and $0.2 million of variable lease costs for the three and six months ended June 30, 2021, respectively, and $0.1 million and $0.4 million for the three and six months ended June 30, 2020, respectively. In addition, $0.1 million and $0.2 million of variable leases costs are included in Selling, general and administrative for the three and six months ended June 30, 2021, respectively, and $0.1 million for both the three and six months ended June 30, 2020. These variable costs consist of our proportionate share of operating expenses, real estate taxes and utilities. (b) Finance lease costs recorded in cost of revenue include variable lease costs of $0.7 million and $1.3 million for the three and six months ended June 30, 2021, respectively, and $0.5 million and $1.2 million for the three and six months ended June 30, 2020, respectively. These variable lease costs consist of fuel, maintenance, and sales tax charges. No variable lease costs for finance leases were recorded in selling, general and administrative. Future minimum commitments for finance and operating leases that have non-cancelable lease terms in excess of one year as of June 30, 2021 were as follows: Year ending (in thousands): Finance Operating Remainder of 2021 $ 1,401 $ 2,479 2022 2,404 4,616 2023 1,409 3,516 2024 598 2,917 2025 50 2,409 Thereafter — 4,043 Total minimum lease payments $ 5,862 $ 19,980 Amounts representing interest (386) Present value of net minimum lease payments $ 5,476 The following is a summary of the lease terms and discount rates: June 30, 2021 December 31, 2020 Weighted average lease term (in years): Operating 5.15 5.48 Finance 2.49 2.78 Weighted average discount rate: Operating 4.84 % 4.83 % Finance 5.45 % 5.50 % The following is a summary of other information and supplemental cash flow information related to finance and operating leases: Six months ended June 30, (in thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,456 $ 2,910 Operating cash flows from finance leases 164 179 Financing cash flows from finance leases 1,318 1,285 Right-of-use assets exchanged for lease liabilities: Operating leases $ 156 $ — Finance leases 336 1,050 Right-of-use assets disposed or adjusted modifying operating leases liabilities $ 36 $ 586 Right-of-use assets disposed or adjusted modifying finance leases liabilities $ — $ (64)

Self-Insurance

Self-Insurance	6 Months Ended
	Jun. 30, 2021
Insurance [Abstract]
Self-Insurance	Self-Insurance The Company purchases workers’ compensation and general liability insurance under policies with per-incident deductibles of $250 thousand and a $4.4 million maximum aggregate deductible loss limit per year. The components of the self-insurance liability as of June 30, 2021 and December 31, 2020 are as follows: (in thousands) June 30, December 31, Current liability — workers’ compensation and general liability $ 105 $ 197 Current liability — medical and dental 511 764 Non-current liability 776 890 Total liability shown in Accrued expenses and other current liabilities $ 1,392 $ 1,851 Restricted cash $ 113 $ 113 The restricted cash balance represents an imprest cash balance set aside for the funding of workers' compensation and general liability insurance claims. This amount is replenished either when depleted or at the beginning of each month.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal. The Company is continually engaged in administrative proceedings, arbitrations, and litigation with owners, general contractors, suppliers, and other unrelated parties, all arising in the ordinary courses of business. In the opinion of the Company’s management, the results of these actions will not have a material adverse effect on the financial position, results of operations, or cash flows of the Company. On November 13, 2019, claimant, Lanzo Trenchless Technologies, Inc. - North, filed a Demand for Arbitration in the state of Michigan against the Company's wholly-owned subsidiary, Limbach Company LLC. The demand seeks damages in excess of $0.4 million based upon the allegation that Limbach breached a construction contract by improperly terminating Lanzo’s subcontract, and for withholding payment from Lanzo based upon deficient performance. Limbach has asserted a counterclaim seeking damages caused by Lanzo’s deficient performance. Lanzo has recently abandoned its claims and the parties are attempting to negotiate a consent judgement in Limbach's favor that will result in the matter being concluded. On January 23, 2020, plaintiff, Bernards Bros. Inc., filed a complaint against Limbach Holdings, Inc. in Superior Court of the State of California for the County of Los Angeles against Limbach Holdings, Inc. The complaint alleges that our Southern California operations refused to honor a proposal made to Bernards to act as a subcontractor on a construction project, and that, as a result of the wrongful failure to honor the proposal, Bernards suffered damages in excess of $3.0 million, including alleged increased costs for hiring a different subcontractor to perform the work. The Company is vigorously defending the suit. A non-binding mediation is scheduled for August 19, 2021 and trial is currently expected to take place in February 2022. On April 17, 2020, plaintiff, LA Excavating, Inc., filed a complaint against our wholly-owned subsidiary, Limbach Company LP, and several other parties, in Superior Court of the State of California, for the County of Los Angeles. The complaint seeks damages of approximately $1.0 million for alleged failure to pay contract balances and extra work ordered by Limbach, as well as seeks to enforce payment obligations under payment and stop notice release bonds. The Company disputes the allegations and intends to vigorously defend the suit, which is currently set for trial in November of 2021. In July of 2020, plaintiff, Kimball Construction Co., Inc., filed a complaint against our wholly-owned subsidiary, Limbach Company LLC in circuit Court for Montgomery County, Maryland. The complaint seeks damages of approximately $1.7 million for alleged failure to pay contract balances and extra work, as well as to enforce payment obligations under a payment bond issued by Limbach's surety provider. The Company and Kimball have reached a cooperative resolution of these claims, which resulted in a Stipulation of Dismissal of the suit on or about June 21, 2021. Surety. The terms of our construction contracts frequently require that we obtain from surety companies, and provide to our customers, payment and performance bonds (“Surety Bonds”) as a condition to the award of such contracts. The Surety Bonds secure our payment and performance obligations under such contracts, and we have agreed to indemnify the surety companies for amounts, if any, paid by them in respect of Surety Bonds issued on our behalf. In addition, at the request of labor unions representing certain of our employees, Surety Bonds are sometimes provided to secure obligations for wages and benefits payable to or for such employees. Public sector contracts require Surety Bonds more frequently than private sector contracts, and accordingly, our bonding requirements typically increase as the amount of public sector work increases. As of June 30, 2021, the Company had approximately $265.3 million in surety bonds outstanding. The Surety Bonds are issued by surety companies in return for premiums, which vary depending on the size and type of bond. Collective Bargaining Agreements. Many of the Company’s craft labor employees are covered by collective bargaining agreements. The agreements require the Company to pay specified wages, provide certain benefits and contribute certain amounts to multi-employer pension plans. If the Company withdraws from any of the multi-employer pension plans or if the plans were to otherwise become underfunded, the Company could incur additional liabilities related to these plans. Although the Company has been informed that some of the multi-employer pension plans to which it contributes have been classified as “critical” status, the Company is not currently aware of any significant liabilities related to this issue.

Remaining Performance Obligatio

Remaining Performance Obligations	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Remaining Performance Obligations	Contract Assets and Liabilities The Company classifies contract assets and liabilities that may be settled beyond one year from the balance sheet date as current, consistent with the length of time of the Company’s project operating cycle. Contract assets include costs in excess of billings and estimated earnings and amounts due under retainage provisions. The components of the contract asset balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract assets Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 $ 6,306 Retainage receivable 32,615 35,204 (2,589) Total contract assets $ 70,815 $ 67,098 $ 3,717 Retainage receivable represents amounts invoiced to customers where payments have been partially withheld, typically 10%, pending the completion of certain milestones, satisfaction of other contractual conditions or the completion of the project. Retainage agreements vary from project to project and balances could be outstanding for several months or years depending on a number of circumstances such as contract-specific terms, project performance and other variables that may arise as the Company makes progress towards completion. Contract assets represent the excess of contract costs and profits (or contract revenue) over the amount of contract billings to date and are classified as a current asset. Contract assets result when either: 1) the appropriate contract revenue amount has been recognized over time in accordance with ASC Topic 606, but a portion of the revenue recorded cannot be currently billed due to the billing terms defined in the contract, or 2) costs are incurred related to certain claims and unapproved change orders. Claims occur when there is a dispute regarding both a change in the scope of work and the price associated with that change. Unapproved change orders occur when a change in the scope of work results in additional work being performed before the parties have agreed on the corresponding change in the contract price. The Company routinely estimates recovery related to claims and unapproved change orders as a form of variable consideration at the most likely amount it expects to receive and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Claims and unapproved change orders are billable upon the agreement and resolution between the contractual parties and after the execution of contractual amendments. Increases in claims and unapproved change orders typically result from costs being incurred against existing or new positions; decreases normally result from resolutions and subsequent billings. The current estimated net realizable value on such claims and unapproved change orders as recorded in contract assets and contract liabilities in the condensed consolidated balance sheets was $40.1 million and $33.6 million as of June 30, 2021 and December 31, 2020, respectively. The Company anticipates that the majority of such amounts will be approved or executed within one year. The resolution of these claims and unapproved change orders may require litigation or other forms of dispute resolution proceedings. Contract liabilities include billings in excess of costs and estimated earnings and provisions for losses. The components of the contract liability balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract liabilities Billings in excess of costs and estimated earnings $ 38,611 $ 46,020 $ (7,409) Provisions for losses 568 628 (60) Total contract liabilities $ 39,179 $ 46,648 $ (7,469) Billings in excess of costs and estimated earnings represent the excess of contract billings to date over the amount of contract costs and profits (or contract revenue) recognized to date. The balance may fluctuate depending on the timing of contract billings and the recognition of contract revenue. Provisions for losses are recognized in the condensed consolidated statements of operations at the uncompleted performance obligation level for the amount of total estimated losses in the period that evidence indicates that the estimated total cost of a performance obligation exceeds its estimated total revenue. The net overbilling position for contracts in process consist of the following: (in thousands) June 30, 2021 December 31, 2020 Revenue earned on uncompleted contracts $ 691,473 $ 752,564 Less: Billings to date (691,884) (766,690) Net overbilling $ (411) $ (14,126) (in thousands) June 30, 2021 December 31, 2020 Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 Billings in excess of costs and estimated earnings (38,611) (46,020) Net overbilling $ (411) $ (14,126) For the three and six months ended June 30, 2021 and 2020, we recorded revisions in our contract estimates for certain GCR and ODR projects. For the three months ended June 30, 2021 and 2020, total net gross profit write-downs were $1.1 million and $2.0 million, respectively. For projects having a material gross profit impact of $0.25 million or more for the three months ended June 30, 2021, this resulted in material gross profit write downs on three GCR segment projects of $1.7 million and one ODR project for $0.3 million. Of the material GCR segment write downs, one project was within the Michigan region for a total of $1.0 million, one project was within the New England region for $0.3 million and one project was within the Southern California region for $0.4 million. Of the material ODR segment write downs, one project was within the Eastern Pennsylvania region for $0.3 million. We also recorded material gross profit write ups of $0.3 million on one GCR segment project in the Florida region and $0.3 million on one ODR segment project in the Michigan region. For the three months ended June 30, 2020, we recorded material revisions in our contract estimates on four GCR projects which resulted in gross profit write downs of $1.5 million. Two of these projects were within the Southern California region for a total of $0.7 million. No project revisions resulting in material gross profit write ups were recorded during the three months ended June 30, 2020. For the six months ended June 30, 2021 and 2020, total net gross profit write-downs were $1.7 million and $3.4 million, respectively. For projects having a material gross profit impact of $0.25 million or more, we recorded gross profit write downs on eight GCR segment projects of $3.5 million and one ODR project for $0.3 million. Of the material GCR segment write downs, two projects were within the Michigan region for a total of $1.2 million, two projects were within the Eastern Pennsylvania region for $1.0 million, two projects were within the Southern California region for $0.8 million, one project was within the New England region for $0.3 million, and one project was within the Mid-Atlantic region for $0.3 million. We also materially wrote down one ODR segment project within the Eastern Pennsylvania region for $0.3 million. We also recorded material GCR segment gross profit write ups of $0.9 million on one GCR segment project in the Michigan region for $0.5 million and one project within the Ohio region for $0.4 million. For the six months ended June 30, 2020, we recorded material gross profit write downs on eight GCR projects and two gross profit write ups on GCR projects, for an aggregate revision of $5.2 million and $1.2 million, respectively. Remaining performance obligations represent the transaction price of firm orders for which work has not been performed and exclude unexercised contract options. The Company’s remaining performance obligations includes projects that have a written award, a letter of intent, a notice to proceed or an agreed upon work order to perform work on mutually accepted terms and conditions. As of June 30, 2021, the aggregate amount of the transaction prices allocated to the remaining performance obligations of the Company's GCR and ODR segment contracts were $378.9 million and $44.2 million, respectively. As of December 31, 2020, the aggregate amount of the transaction prices allocated to the remaining performance obligations of the Company's GCR and ODR segment contracts were $393.5 million and $35.7 million, respectively. We estimate that 44% and 62% of our GCR and ODR segment remaining performance obligations as of June 30, 2021, respectively, will be recognized as revenue during 2021, with the substantial majority of remaining performance obligations to be recognized within 24 months, although the timing of the Company's performance is not always under its control. Additionally, the difference between remaining performance obligations and backlog is due to the exclusion of a portion of the Company’s ODR agreements under certain contract types from the Company’s remaining performance obligations as these contracts can be canceled for convenience at any time by the Company or the customer without considerable cost incurred by the customer. Additional information related to backlog is provided in “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations” of this Quarterly Report on Form 10-Q.

Management Incentive Plans

Management Incentive Plans	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Management Incentive Plans	Management Incentive Plans The Company initially adopted the Omnibus Incentive Plan on July 20, 2016 for the purpose of: (a) encouraging the profitability and growth of the Company through short-term and long-term incentives that are consistent with the Company’s objectives; (b) giving participants an incentive for excellence in individual performance; (c) promoting teamwork among participants; and (d) giving the Company a significant advantage in attracting and retaining key employees, directors and consultants. To accomplish such purposes, the Omnibus Incentive Plan provides that the Company may grant options, stock appreciation rights, restricted shares, restricted stock units, performance-based awards (including performance-based restricted shares and restricted stock units), other share based awards, other cash-based awards or any combination of the foregoing. Following the further amendment and restatement of the Omnibus Incentive Plan upon approval of the Company's stockholders on June 16, 2021, the Company has reserved a total of 2,250,000 shares of its common stock for issuance under the Omnibus Incentive Plan. The number of shares issued or reserved pursuant to the Omnibus Incentive Plan will be adjusted by the plan administrator, as they deem appropriate and equitable, as a result of stock splits, stock dividends, and similar changes in the Company’s common stock. In connection with the grant of an award, the plan administrator may provide for the treatment of such award in the event of a change in control. All awards are made in the form of shares only. Service-Based Awards During the first six months of 2021, the Company granted 120,899 service-based RSUs to its executives, certain employees, and non-employee directors under the Omnibus Incentive Plan. The following table summarizes our service-based RSU activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 285,799 $ 6.32 Granted 120,899 12.25 Vested (106,383) 6.66 Forfeited (2,333) 8.27 Unvested at June 30, 2021 297,982 $ 8.59 Performance-Based Awards During the first six months of 2021, the Company granted 185,367 performance-based RSUs (“PRSUs”) to its executives and certain employees under the Omnibus Incentive Plan. The Company will recognize stock-based compensation expense for these awards over the vesting period based on the projected probability of achievement of certain performance conditions as of the end of each reporting period during the performance period and may periodically adjust the recognition of such expense, as necessary, in response to any changes in the Company’s forecasts with respect to the performance conditions. For the three and six months ended June 30, 2021, the Company recognized $0.2 million and $0.4 million, respectively, of stock-based compensation expense related to outstanding PRSUs. For the three and six months ended June 30, 2020, the Company recognized $0.1 million of stock-based compensation expense related to outstanding PRSUs. The following table summarizes our PRSU activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 99,500 $ 4.23 Granted 185,367 12.26 Vested — — Forfeited (4,167) 8.92 Unvested at June 30, 2021 280,700 $ 9.46 Market-Based Awards On September 4, 2020, the Compensation Committee (the “Committee”) of the Board of Directors of the Company approved amendments to certain restricted stock units initially awarded on August 30, 2017 by the Company to certain employees. Pursuant to the amendment adopted on September 4, 2020, the measurement period was extended to July 16, 2022. In addition to the market performance-based vesting condition, the vesting of such restricted stock unit is subject to continued employment from August 1, 2017 through the later of July 31, 2019 or the date on which the Committee certifies the achievement of the performance goal. The Company has accounted for this amendment as a Type I modification and will recognize approximately $0.2 million of incremental stock-based compensation expense over 1.26 years based on an updated Monte Carlo simulation model. The following table summarizes our market-based RSU (“MRSUs”) activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 102,500 $ 8.26 Granted — — Vested — — Forfeited — — Unvested at June 30, 2021 102,500 $ 8.26 Total recognized stock-based compensation expense amounted to $0.7 million and $1.3 million for the three and six months ended June 30, 2021, respectively, and $0.1 million and $0.4 million for the three and six months ended June 30, 2020, respectively. The aggregate fair value as of the vest date of RSUs that vested during the six months ended June 30, 2021 and 2020 was $1.3 million and $0.6 million, respectively. Total unrecognized stock-based compensation expense related to unvested RSUs which are probable of vesting was $3.6 million at June 30, 2021. These costs are expected to be recognized over a weighted average period of 2.0 years.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Condensed Consolidated Financial Statements The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with instructions to the Quarterly Report on Form 10-Q and Rule 8-03 of Regulation S-X for smaller reporting companies. Consequently, certain information and note disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. Readers of this report should refer to the consolidated financial statements and the notes thereto included in our most recent Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 25, 2021.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying interim Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Stockholders’ Equity and Condensed Consolidated Statements of Cash Flows for the periods presented are unaudited. Also, within the notes to the Condensed Consolidated Financial Statements, we have included unaudited information for these interim periods. These unaudited interim Condensed Consolidated Financial Statements have been prepared in accordance with GAAP. In our opinion, the accompanying unaudited Condensed Consolidated Financial Statements contain all normal and recurring adjustments necessary for a fair statement of the Company’s financial position as of June 30, 2021, its results of operations and its cash flows for the three and six months ended June 30, 2021. The results for the three and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021. The Condensed Consolidated Balance Sheet as of December 31, 2020 was derived from our audited financial statements included in our Annual Report on Form 10-K filed with the SEC on March 25, 2021, but is presented as condensed and does not contain all of the footnote disclosures from the annual financial statements.
Recently Adopted Accounting Standards and Recent Accounting Pronouncements	Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), which affects general principles within Topic 740, and is meant to simplify and reduce the cost of accounting for income taxes. It removes certain exceptions to the general principles in Topic 740 and simplifies areas including franchise taxes that are partially based on income, transactions with a government that result in a step up in the tax basis of goodwill, the incremental approach for intraperiod tax allocation, interim period income tax accounting for year-to-date losses that exceed anticipated losses and enacted changes in tax laws in interim periods. The changes are effective for annual periods beginning after December 15, 2020. The adoption of this pronouncement did not have a material impact on our condensed consolidated financial statements or presentation thereof. Also in October 2020, the FASB issued ASU 2020-10, Codification Improvements. The amendments in this update remove references to various FASB Concepts Statements, situates all disclosure guidance in the appropriate disclosure section of the Codification, and makes other improvements and technical corrections to the Codification. The amendments in Sections B and C of this amendment are effective for annual periods beginning after December 15, 2020, for public business entities, with early adoption permitted. The adoption of this pronouncement did not have a material impact on our condensed consolidated financial statements or presentation thereof. Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments, which introduced an expected credit loss methodology for the measurement and recognition of credit losses on most financial instruments, including trade receivables and off-balance sheet credit exposure. Under this guidance, an entity is required to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. This ASU also requires disclosure of information regarding how a company developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes. The guidance is effective for smaller reporting companies on January 1, 2023 with early adoption permitted. The adoption of this standard will be through a cumulative-effect adjustment to retained earnings as of the effective date. Based on our historical experience, the Company does not expect that this pronouncement will have a significant impact in its financial statements or on the estimate of the allowance for doubtful accounts. The FASB has issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting in March 2020. This new guidance provides optional expedients for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform, on financial reporting. The risk of termination of the London Interbank Offered Rate (LIBOR), has caused regulators to undertake reference rate reform initiatives to identify alternative reference rates that are more observable or transaction based that are less susceptible to manipulation. ASU 2020-04 is effective between March 12, 2020 and December 31, 2022. In addition, in January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope. The amendments in this update refine the scope for certain optional expedients and exceptions for contract modifications and hedge accounting to apply to derivative contracts and certain hedging relationships affected by the discounting transition. The amendments in this update are effective for all entities as of March 12, 2020 through December 31, 2022. The Company is currently evaluating the impact of adopting the reference rate reform guidance (both ASU 2020-04 and ASU 2021-01) on its condensed consolidated financial statements. Management has identified that its credit agreement utilizes LIBOR as a benchmark rate. Management will continue to evaluate the impact of adopting reference rate reform as the LIBOR benchmark rate within the credit agreement is phased out. In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity and amends the scope guidance for contracts in an entity's own equity. The ASU addresses how convertible instruments are accounted for in the calculation of diluted earnings per share by using the if-converted method. The guidance is effective for all entities for fiscal years beginning after March 31, 2024, albeit early adoption is permitted no earlier than fiscal years beginning after December 15, 2020. Management is currently assessing the impact of this pronouncement on its condensed consolidated financial statements.
Fair Value Measurements	The Company measures the fair value of financial assets and liabilities in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures, which defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to measurements involving significant unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows: • Level 1 — inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that are accessible at the measurement date; • Level 2 — inputs other than quoted prices included in Level 1 that are observable for the asset or liability either directly or indirectly such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities; and • Level 3 — unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

Accounts Receivable and Allow_2

Accounts Receivable and Allowance for Doubtful Accounts (Tables)	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
Schedule of Components of Accounts Receivable and Allowance for Doubtful Accounts	Accounts receivable and the allowance for doubtful accounts are comprised of the following: (in thousands) June 30, 2021 December 31, 2020 Accounts receivable - trade $ 94,881 $ 86,033 Allowance for doubtful accounts (266) (266) Accounts receivable, net $ 94,615 $ 85,767

Contract Assets and Liabiliti_2

Contract Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Components of Contract Asset and Liability Balances	Contract assets include costs in excess of billings and estimated earnings and amounts due under retainage provisions. The components of the contract asset balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract assets Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 $ 6,306 Retainage receivable 32,615 35,204 (2,589) Total contract assets $ 70,815 $ 67,098 $ 3,717 Contract liabilities include billings in excess of costs and estimated earnings and provisions for losses. The components of the contract liability balances as of the respective dates were as follows: (in thousands) June 30, 2021 December 31, 2020 Change Contract liabilities Billings in excess of costs and estimated earnings $ 38,611 $ 46,020 $ (7,409) Provisions for losses 568 628 (60) Total contract liabilities $ 39,179 $ 46,648 $ (7,469)
Schedule of Contracts In Progress	The net overbilling position for contracts in process consist of the following: (in thousands) June 30, 2021 December 31, 2020 Revenue earned on uncompleted contracts $ 691,473 $ 752,564 Less: Billings to date (691,884) (766,690) Net overbilling $ (411) $ (14,126) (in thousands) June 30, 2021 December 31, 2020 Costs in excess of billings and estimated earnings $ 38,200 $ 31,894 Billings in excess of costs and estimated earnings (38,611) (46,020) Net overbilling $ (411) $ (14,126)

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets are comprised of the following: (in thousands) Gross Accumulated Net intangible June 30, 2021 (1) Amortized intangible assets: Customer Relationships – ODR $ 4,710 $ (3,312) $ 1,398 Favorable Leasehold Interests (2) 190 (75) 115 Total amortized intangible assets 4,900 (3,387) 1,513 Unamortized intangible assets: Trade Name 9,960 — 9,960 Total unamortized intangible assets 9,960 — 9,960 Total amortized and unamortized assets, excluding goodwill $ 14,860 $ (3,387) $ 11,473 (in thousands) Gross Accumulated Net intangible December 31, 2020 (1) Amortized intangible assets: Customer Relationships – ODR $ 4,710 $ (3,112) $ 1,598 Favorable Leasehold Interests 530 (407) 123 Total amortized intangible assets 5,240 (3,519) 1,721 Unamortized intangible assets: Trade Name 9,960 — 9,960 Total unamortized intangible assets 9,960 — 9,960 Total amortized and unamortized assets, excluding goodwill $ 15,200 $ (3,519) $ 11,681 (1) The Backlog-Construction intangible asset previously shown at December 31, 2020 has been fully amortized. Accordingly, its gross carrying amount of $4.8 million and corresponding accumulated amortization of $4.8 million have been removed from the table. (2) The gross carrying amount and accumulated amortization associated with our Favorable leasehold interests intangible asset was reduced by $0.3 million due to the lease termination of our Western Pennsylvania office associated with the intangible asset.

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	Long-term debt consists of the following obligations as of: (in thousands) June 30, 2021 December 31, 2020 2019 Refinancing Term Loan - term loan payable in quarterly installments of principal, (commencing in September 2020) plus interest through April 2022 $ — $ 39,000 2019 Refinancing Revolving Credit Facility — — Wintrust Term Loan - term loan payable in quarterly installments of principal, (commencing in March 2021) plus interest through February 2026 28,000 — Wintrust Revolving Loan — — Finance leases – collateralized by vehicles, payable in monthly installments of principal, plus interest ranging from 4.70% to 6.45% through 2025 5,476 6,459 Total debt 33,476 45,459 Less - Current portion of long-term debt (8,454) (6,536) Less - Unamortized discount and debt issuance costs (301) (2,410) Long-term debt $ 24,721 $ 36,513
Schedule of Additional Margin and Commitment Fees Payable	The following is a summary of the additional margin and commitment fees payable on the available Wintrust Term Loan and Wintrust Revolving Loan credit commitment: Level Senior Leverage Ratio Additional Margin for Additional Margin for Additional Margin for Eurodollar Term loans Additional Margin for Eurodollar Revolving loans Commitment Fee I Greater than 1.00 to 1.00 1.00 % 0.50 % 4.00 % 3.50 % 0.25 % II Less than or equal to 1.00 to 1.00 0.25 % — % 3.50 % 3.00 % 0.25 %

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Schedule of Outstanding Warrants	June 30, 2021 December 31, 2020 Public Warrants (1)(5) 2,140,219 2,300,000 Private Warrants (1)(5) 99,000 99,000 $15 Exercise Price Sponsor Warrants (2)(5) 600,000 600,000 Merger Warrants (3)(6) 629,643 631,119 Additional Merger Warrants (4)(6) 935,068 946,680 Total 4,403,930 4,576,799 (1) Exercisable for one-half of one share of common stock at an exercise price of $5.75 per half share ($11.50 per whole share) (2) Exercisable for one share of common stock at an exercise price of $15.00 per share (3) Exercisable for one share of common share at an exercise price of $12.50 per share (4) Exercisable for one share of common stock at an exercise price of $11.50 per share (5) Issued under a warrant agreement dated July 15, 2014, between Continental Stock Transfer and Trust Company, as warrant agent, and the Company (6) Issued to the sellers of LHLLC Subsequent to June 30, 2021, on July 20, 2021, the Public Warrants, Private Warrants, and Additional Merger Warrants expired by their terms.

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Three months ended June 30, Six months ended June 30, (in thousands, except per share amounts) 2021 2020 2021 2020 EPS numerator: Net income (loss) $ 732 $ 2,947 $ (1,550) $ 2,895 EPS denominator: Weighted average shares outstanding – basic 10,252 7,846 9,738 7,822 Impact of dilutive securities 217 59 — 56 Weighted average shares outstanding – diluted 10,469 7,905 9,738 7,878 EPS: Basic $ 0.07 $ 0.38 $ (0.16) $ 0.37 Diluted $ 0.07 $ 0.37 $ (0.16) $ 0.37
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes the securities that were antidilutive or out-of-the-money, and therefore, were not included in the computations of diluted loss per common share: Three months ended June 30, Six months ended June 30, 2021 2020 2021 2020 In-the-money warrants — — — — Out-of-the-money warrants (see Note 8) 4,403,930 4,576,799 4,403,930 4,576,799 Service-based RSUs (See Note 17) 334 463 142,120 1,255 Performance and market-based RSUs (1) 13,929 9,674 79,971 — Employee Stock Purchase Plan — — 4,778 — Total 4,418,193 4,586,936 4,630,799 4,578,054 (1) For the three and six months ended June 30, 2021 and 2020, certain PRSU and MRSU awards were not included in the computation of diluted loss per share because the performance and market conditions were not satisfied during the periods and would not be satisfied if the reporting date was at the end of the contingency period.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Unrecognized Tax Benefits	The following is a reconciliation of the beginning and ending unrecognized tax benefits: June 30, 2021 December 31, 2020 Balance at beginning of period $ — $ 1,130 Gross increases in prior period tax positions — — Gross increases in current period tax positions — — Decreases related to prior year tax positions — (1,130) Balance at end of period $ — $ —

Operating Segments (Tables)

Operating Segments (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Condensed Consolidated Segment Information	Condensed consolidated segment information for the three months ended June 30, 2021 and 2020 is as follows: Three months ended June 30, (in thousands) 2021 2020 Statement of Operations Data: Revenue: GCR $ 87,550 $ 105,937 ODR 33,469 29,248 Total revenue 121,019 135,185 Gross profit: GCR 8,885 12,213 ODR 9,805 8,122 Total gross profit 18,690 20,335 Selling, general and administrative: GCR 9,070 8,024 ODR 7,526 5,588 Corporate 636 140 Total selling, general and administrative 17,232 13,752 Amortization of intangibles 104 274 Operating income $ 1,354 $ 6,309 Operating income for reportable segments $ 1,354 $ 6,309 Less unallocated amounts: Interest expense, net (452) (2,137) Gain (loss) on disposition of property and equipment 94 (13) Loss on change in fair value of warrant liability — (102) Total unallocated amounts (358) (2,252) Income before income taxes $ 996 $ 4,057 Other Data: Depreciation and amortization: GCR $ 1,020 $ 1,032 ODR 345 330 Corporate 104 274 Total other data $ 1,469 $ 1,636 Summarized segment information is as follows: Three months ended June 30, 2021 Three months ended June 30, 2020 (in thousands) GCR ODR Total GCR ODR Total Revenue $ 87,550 $ 33,469 $ 121,019 $ 105,937 $ 29,248 $ 135,185 Gross Profit 8,885 9,805 18,690 12,213 8,122 20,335 Selling, general and administrative 9,070 7,526 16,596 8,024 5,588 13,612 EBIT $ (185) $ 2,279 $ 2,094 $ 4,189 $ 2,534 $ 6,723 Condensed consolidated segment information for the six months ended June 30, 2021 and 2020 is as follows: Six months ended June 30, (in thousands) 2021 2020 Statement of Operations Data: Revenue: GCR $ 172,354 $ 215,423 ODR 62,009 58,534 Total revenue 234,363 273,957 Gross profit: GCR 18,280 23,195 ODR 17,639 15,364 Total gross profit 35,919 38,559 Selling, general and administrative: GCR 18,184 18,200 ODR 14,880 11,917 Corporate 1,313 435 Total selling, general and administrative 34,377 30,552 Amortization of intangibles 208 417 Operating income $ 1,334 $ 7,590 Operating income for reportable segments $ 1,334 $ 7,590 Less unallocated amounts: Interest expense, net (1,716) (4,295) Gain on disposition of property and equipment 8 17 Loss on early debt extinguishment (1,961) — Gain on change in fair value of warrant liability 14 59 Total unallocated amounts (3,655) (4,219) (Loss) income before income taxes $ (2,321) $ 3,371 Other Data: Depreciation and amortization: GCR $ 2,056 $ 2,062 ODR 700 661 Corporate 208 417 Total other data $ 2,964 $ 3,140 Summarized segment information is as follows: Six months ended June 30, 2021 Six months ended June 30, 2020 (in thousands) GCR ODR Total GCR ODR Total Revenue $ 172,354 $ 62,009 $ 234,363 $ 215,423 $ 58,534 $ 273,957 Gross Profit 18,280 17,639 35,919 23,195 15,364 38,559 Selling, general and administrative 18,184 14,880 33,064 18,200 11,917 30,117 EBIT $ 96 $ 2,759 $ 2,855 $ 4,995 $ 3,447 $ 8,442
Schedule of Reconciliation of Segment Gross Profit to Income Before Income Taxes	Reconciliation of segment gross profit to income before income taxes: Three months ended June 30, (in thousands) 2021 2020 Total gross profit from reportable segments $ 18,690 $ 20,335 Selling, general and administrative (17,232) (13,752) Amortization of intangibles (104) (274) Total other expenses (358) (2,252) Income before income taxes $ 996 $ 4,057 Reconciliation of segment gross profit to (loss) income before income taxes: Six months ended June 30, (in thousands) 2021 2020 Total gross profit from reportable segments $ 35,919 $ 38,559 Selling, general and administrative (34,377) (30,552) Amortization of intangibles (208) (417) Total other expenses (3,655) (4,219) (Loss) income before income taxes $ (2,321) $ 3,371

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Supplemental Balance Sheets Information	The following table summarizes the lease amounts included in our condensed consolidated balance sheets: (in thousands) Classification on the Condensed Consolidated Balance Sheets June 30, 2021 December 31, 2020 Assets Operating Operating lease right-of-use assets (a) $ 16,852 $ 18,751 Finance Property and equipment, net (b) 5,251 6,242 Total lease assets $ 22,103 $ 24,993 Liabilities Current Operating Current operating lease liabilities $ 4,122 $ 3,929 Finance Current portion of long-term debt 2,454 2,536 Noncurrent Operating Long-term operating lease liabilities 13,454 15,459 Finance Long-term debt 3,022 3,923 Total lease liabilities $ 23,052 $ 25,847 (a) Operating lease assets are recorded net of accumulated amortization of $13.9 million at June 30, 2021 and $11.9 million at December 31, 2020. (b) Finance lease assets are recorded net of accumulated amortization of $5.6 million at June 30, 2021 and $5.3 million at December 31, 2020.
Summary of Lease Costs, Lease Terms and Discount Rates	The following table summarizes the lease costs included in our condensed consolidated statements of operations for the three and six months ended June 30, 2021 and 2020: Three months ended June 30, Six months ended June 30, (in thousands) Classification on the Condensed Consolidated Statement of Operations 2021 2020 2021 2020 Operating lease cost Cost of revenue (a) $ 685 $ 893 $ 1,375 $ 1,777 Operating lease cost Selling, general and administrative (a) 584 376 1,169 757 Finance lease cost Amortization Cost of revenue (b) 652 645 1,327 1,311 Interest Interest expense, net (b) 78 86 164 179 Total lease cost $ 1,999 $ 2,000 $ 4,035 $ 4,024 (a) Operating lease costs recorded in cost of sales includes $0.1 million and $0.2 million of variable lease costs for the three and six months ended June 30, 2021, respectively, and $0.1 million and $0.4 million for the three and six months ended June 30, 2020, respectively. In addition, $0.1 million and $0.2 million of variable leases costs are included in Selling, general and administrative for the three and six months ended June 30, 2021, respectively, and $0.1 million for both the three and six months ended June 30, 2020. These variable costs consist of our proportionate share of operating expenses, real estate taxes and utilities. (b) Finance lease costs recorded in cost of revenue include variable lease costs of $0.7 million and $1.3 million for the three and six months ended June 30, 2021, respectively, and $0.5 million and $1.2 million for the three and six months ended June 30, 2020, respectively. These variable lease costs consist of fuel, maintenance, and sales tax charges. No variable lease costs for finance leases were recorded in selling, general and administrative. The following is a summary of the lease terms and discount rates: June 30, 2021 December 31, 2020 Weighted average lease term (in years): Operating 5.15 5.48 Finance 2.49 2.78 Weighted average discount rate: Operating 4.84 % 4.83 % Finance 5.45 % 5.50 %
Future Minimum Commitment for Finance Leases	Future minimum commitments for finance and operating leases that have non-cancelable lease terms in excess of one year as of June 30, 2021 were as follows: Year ending (in thousands): Finance Operating Remainder of 2021 $ 1,401 $ 2,479 2022 2,404 4,616 2023 1,409 3,516 2024 598 2,917 2025 50 2,409 Thereafter — 4,043 Total minimum lease payments $ 5,862 $ 19,980 Amounts representing interest (386) Present value of net minimum lease payments $ 5,476
Future Minimum Commitment for Operating Leases	Future minimum commitments for finance and operating leases that have non-cancelable lease terms in excess of one year as of June 30, 2021 were as follows: Year ending (in thousands): Finance Operating Remainder of 2021 $ 1,401 $ 2,479 2022 2,404 4,616 2023 1,409 3,516 2024 598 2,917 2025 50 2,409 Thereafter — 4,043 Total minimum lease payments $ 5,862 $ 19,980 Amounts representing interest (386) Present value of net minimum lease payments $ 5,476
Leases Supplemental Cash Flow Information	The following is a summary of other information and supplemental cash flow information related to finance and operating leases: Six months ended June 30, (in thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,456 $ 2,910 Operating cash flows from finance leases 164 179 Financing cash flows from finance leases 1,318 1,285 Right-of-use assets exchanged for lease liabilities: Operating leases $ 156 $ — Finance leases 336 1,050 Right-of-use assets disposed or adjusted modifying operating leases liabilities $ 36 $ 586 Right-of-use assets disposed or adjusted modifying finance leases liabilities $ — $ (64)

Self-Insurance (Tables)

Self-Insurance (Tables)	6 Months Ended
	Jun. 30, 2021
Insurance [Abstract]
Schedule of Components of Self-Insurance	The components of the self-insurance liability as of June 30, 2021 and December 31, 2020 are as follows: (in thousands) June 30, December 31, Current liability — workers’ compensation and general liability $ 105 $ 197 Current liability — medical and dental 511 764 Non-current liability 776 890 Total liability shown in Accrued expenses and other current liabilities $ 1,392 $ 1,851 Restricted cash $ 113 $ 113

Management Incentive Plans (Tab

Management Incentive Plans (Tables)	6 Months Ended
	Jun. 30, 2021
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes our service-based RSU activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 285,799 $ 6.32 Granted 120,899 12.25 Vested (106,383) 6.66 Forfeited (2,333) 8.27 Unvested at June 30, 2021 297,982 $ 8.59
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes our PRSU activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 99,500 $ 4.23 Granted 185,367 12.26 Vested — — Forfeited (4,167) 8.92 Unvested at June 30, 2021 280,700 $ 9.46
MRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes our market-based RSU (“MRSUs”) activity for the six months ended June 30, 2021: Awards Weighted-Average Unvested at December 31, 2020 102,500 $ 8.26 Granted — — Vested — — Forfeited — — Unvested at June 30, 2021 102,500 $ 8.26

Organization and Plan of Busi_2

Organization and Plan of Business Operations (Details)	1 Months Ended	6 Months Ended	18 Months Ended
	Jul. 31, 2020	Jun. 30, 2021approachsegment	Jun. 30, 2021
Unusual or Infrequent Item, or Both [Line Items]
Number of reportable segments		2
Number distinct approaches to customer base | approach		2
Number of operating segments		2
Service period		2 years
COVID 19
Unusual or Infrequent Item, or Both [Line Items]
Salary reduction percentage	0.10		0.10
Fee reduction percentage on director compensation	0.10		0.10
COVID 19 | Minimum
Unusual or Infrequent Item, or Both [Line Items]
Suspension period of non-essential expenses			1 month
COVID 19 | Maximum
Unusual or Infrequent Item, or Both [Line Items]
Suspension period of non-essential expenses			3 months

Accounts Receivable and Allow_3

Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Receivables [Abstract]
Accounts receivable - trade	$ 94,881	$ 86,033
Allowance for doubtful accounts	(266)	(266)
Accounts receivable, net	$ 94,615	$ 85,767

Contract Assets and Liabiliti_3

Contract Assets and Liabilities - Components of Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Contract assets
Costs in excess of billings and estimated earnings	$ 38,200		$ 31,894
Retainage receivable	32,615		35,204
Total contract assets	70,815		67,098
Change in costs in excess of billings and estimated earnings	6,306
Change in retainage receivable	(2,589)
Change in contract assets	3,717	$ (4,901)
Contract liabilities
Billings in excess of costs and estimated earnings	38,611		46,020
Provisions for losses	568		628
Total contract liabilities	39,179		$ 46,648
Change in billings in excess of costs and estimated earnings	(7,409)
Change in provisions for losses	(60)
Change in contract liabilities	$ (7,469)	$ 16,254

Contract Assets and Liabiliti_4

Contract Assets and Liabilities - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)project	Jun. 30, 2020USD ($)project	Jun. 30, 2021USD ($)project	Jun. 30, 2020USD ($)project	Dec. 31, 2020USD ($)
Property, Plant and Equipment [Line Items]
Percentage completed of certain milestones			10.00%
Net realizable value of unapproved orders	$ 40,100		$ 40,100		$ 33,600
Gross profit write downs	1,100	$ 2,000	1,700	$ 3,400
Revision amount for gross profit impact on contract estimates (more than)	250		250
Number of projects subject to gross profit write ups | project		0
GCR
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 1,700	$ 1,500	$ 3,500	$ 5,200
Number of projects subject to gross profit write downs | project	3	4	8	8
Gross profit write ups			$ 900	$ 1,200
Number of projects subject to gross profit write ups | project				2
GCR | Michigan Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 1,000		$ 1,200
Number of projects subject to gross profit write downs | project	1		2
Gross profit write ups			$ 500
Number of projects subject to gross profit write ups | project			1
GCR | New England Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1
GCR | Southern California Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 400	$ 700	$ 800
Number of projects subject to gross profit write downs | project	1	2	2
GCR | Eastern Pennsylvania Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs			$ 1,000
Number of projects subject to gross profit write downs | project			2
GCR | Florida Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups	$ 300
Number of projects subject to gross profit write ups | project	1
GCR | Mid-Atlantic Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs			$ 300
Number of projects subject to gross profit write downs | project			1
GCR | Ohio Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups			$ 400
Number of projects subject to gross profit write ups | project			1
ODR
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1
ODR | Michigan Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups	$ 300
Number of projects subject to gross profit write ups | project	1
ODR | Eastern Pennsylvania Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1

Contract Assets and Liabiliti_5

Contract Assets and Liabilities - Contracts In Progress (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue earned on uncompleted contracts	$ 691,473	$ 752,564
Less: Billings to date	(691,884)	(766,690)
Net overbilling	(411)	(14,126)
Costs in excess of billings and estimated earnings	38,200	31,894
Billings in excess of costs and estimated earnings	$ (38,611)	$ (46,020)

Goodwill and Intangibles - Narr

Goodwill and Intangibles - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 6,129,000		$ 6,129,000		$ 6,129,000
Amortization of intangibles	104,000	$ 274,000	208,000	$ 417,000
Impairment of goodwill	0	0	0	0
Impairment of intangible assets (excluding goodwill)	$ 0	$ 0	$ 0	$ 0

Goodwill and Intangibles Assets

Goodwill and Intangibles Assets - Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Amortized intangible assets:
Gross carrying amount	$ 4,900	$ 5,240
Accumulated amortization	(3,387)	(3,519)
Net intangible assets, excluding goodwill	1,513	1,721
Unamortized intangible assets:
Gross carrying amount	9,960	9,960
Net intangible assets, excluding goodwill	9,960	9,960
Gross carrying amount	14,860	15,200
Accumulated amortization	(3,387)	(3,519)
Total amortized and unamortized assets, excluding goodwill	11,473	11,681
Trade Name
Unamortized intangible assets:
Gross carrying amount	9,960	9,960
Net intangible assets, excluding goodwill	9,960	9,960
Customer Relationships | ODR
Amortized intangible assets:
Gross carrying amount	4,710	4,710
Accumulated amortization	(3,312)	(3,112)
Net intangible assets, excluding goodwill	1,398	1,598
Unamortized intangible assets:
Accumulated amortization	(3,312)	(3,112)
Favorable Leasehold Interests
Amortized intangible assets:
Gross carrying amount	190	530
Accumulated amortization	(75)	(407)
Net intangible assets, excluding goodwill	115	123
Unamortized intangible assets:
Accumulated amortization	(75)	(407)
Reduction in gross carrying amount and accumulated amortization of intangibles due to lease termination	$ 300
Backlog – Construction
Amortized intangible assets:
Gross carrying amount		4,800
Accumulated amortization		(4,800)
Unamortized intangible assets:
Accumulated amortization		$ (4,800)

Debt - Schedule of Long-Term De

Debt - Schedule of Long-Term Debt (Details) - USD ($)	Feb. 24, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Finance leases – collateralized by vehicles, payable in monthly installments of principal, plus interest ranging from 4.70% to 6.45% through 2025		$ 5,476,000		$ 5,476,000		$ 6,459,000
Total debt		33,476,000		33,476,000		45,459,000
Less - Current portion of long-term debt		(8,454,000)		(8,454,000)		(6,536,000)
Less - Unamortized discount and debt issuance costs		(301,000)		(301,000)		(2,410,000)
Long-term debt		24,721,000		24,721,000		36,513,000
Loss on early debt extinguishment		$ 0	$ 0	1,961,000	$ 0
Prepayment penalty and other costs associated with early debt extinguishment				$ 1,376,000	$ 0
Minimum
Debt Instrument [Line Items]
Finance lease, discount rate		4.70%		4.70%
Maximum
Debt Instrument [Line Items]
Finance lease, discount rate		6.45%		6.45%
2019 Refinancing Term Loan - term loan payable in quarterly installments of principal, (commencing in September 2020) plus interest through April 2022
Debt Instrument [Line Items]
Long term debt						39,000,000
2019 Refinancing Agreement
Debt Instrument [Line Items]
Loss on early debt extinguishment	$ 2,000,000
Write off of debt issuance and discount costs	2,600,000
Reversal or warrant liability	2,000,000
Prepayment penalty and other costs associated with early debt extinguishment	$ 1,400,000
Secured Debt | 2019 Refinancing Term Loan - term loan payable in quarterly installments of principal, (commencing in September 2020) plus interest through April 2022
Debt Instrument [Line Items]
Long term debt		$ 0		$ 0		39,000,000
Secured Debt | Wintrust Term Loan - term loan payable in quarterly installments of principal, (commencing in March 2021) plus interest through February 2026
Debt Instrument [Line Items]
Long term debt		28,000,000		28,000,000		0
Revolving Credit Facility | 2019 Refinancing Revolving Credit Facility
Debt Instrument [Line Items]
Long term debt		0		0		0
Revolving Credit Facility | Wintrust Revolving Loan
Debt Instrument [Line Items]
Long term debt		$ 0		$ 0		$ 0

Debt - 2019 Refinancing Agreeme

Debt - 2019 Refinancing Agreement (Details)	Jul. 01, 2021	Apr. 01, 2021	Jan. 01, 2020	Oct. 01, 2019USD ($)	Jun. 30, 2019	Apr. 12, 2019USD ($)covenant	Sep. 30, 2020USD ($)	Mar. 31, 2020	Jun. 30, 2021USD ($)shares	Sep. 30, 2020	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)shares	Jun. 30, 2020USD ($)	Sep. 30, 2020USD ($)	Feb. 24, 2021USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	Nov. 30, 2019USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Gain (loss) on change in fair value of warrant liability									$ 0		$ (102,000)	$ 14,000	$ 59,000
Amortization of debt issuance costs												$ 220,000	1,080,000
2019 Refinancing Agreement
Debt Instrument [Line Items]
Debt issued						$ 40,000,000
Debt effective interest rate									13.00%			13.00%			13.00%
Debt installment payments							$ 1,000,000
Unused line fee percentage							2.00%
Make-whole premium prepayment period							19 months
Make-whole provision applicable to interest period							18 months
Number of financial covenants | covenant						2
Leverage ratio		200.00%		330.00%	425.00%			425.00%
Debt instrument, interest rate, increase (decrease)			1.00%
Warrants tem									5 years			5 years
Warrants liability									$ 0			$ 0			$ 2,000,000	$ 2,000,000		$ 900,000
Derivative liability																		$ 400,000
Gain (loss) on change in fair value of warrant liability									0		100,000	100,000	(100,000)
Debt instrument, unamortized discount															1,300,000
Debt issuance costs, net															3,900,000
Interest expense, debt									$ 0			$ 100,000
Amortization of debt issuance costs											400,000		700,000
2019 Refinancing Agreement | Subsequent Event | Forecast
Debt Instrument [Line Items]
Leverage ratio	200.00%
2019 Refinancing Agreement | Maximum
Debt Instrument [Line Items]
Leverage ratio										400.00%
2019 Refinancing Agreement | LIBOR Rate
Debt Instrument [Line Items]
Basis spread on variable rate						11.00%
2019 Refinancing Agreement | LIBOR Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate						2.00%
2019 Refinancing Agreement | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate						10.00%
2019 Refinancing Agreement | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate						3.00%
2019 Refinancing Amendment Number One and Waiver
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 15,000,000
Unused line fee percentage														50.10%
Leverage ratio		200.00%		330.00%				425.00%
Debt instrument, interest rate, increase (decrease)														3.00%
Debt instrument, percentage of customer accounts required to approve amendment				75.00%
Debt instrument, non refundable waiver fee														$ 400,000
Debt instrument, non refundable amendment fee														$ 1,000,000
2019 Refinancing Amendment Number One and Waiver | Minimum
Debt Instrument [Line Items]
Debt instrument, liquidity of loan parties																	$ 10,000,000
2019 Refinancing Term Loan
Debt Instrument [Line Items]
Collateral coverage amount																37,900,000
Debt outstanding																39,000,000
Debt outstanding balance in excess of collateral coverage amount																$ 1,100,000
2019 Refinancing Term Loan - CB Warrants
Debt Instrument [Line Items]
Debt outstanding															0
Class of warrant or right, number of securities called by each warrant or right (in shares) | shares									0			0				263,314
Exercise price of warrants (in usd per share) | $ / shares																$ 7.63
Percentage of number of shares												2.00%
Interest expense, debt									$ 0			$ 100,000
Amortization of debt issuance costs											$ 100,000		$ 200,000
Refinancing Agreement 2019 First Amendment
Debt Instrument [Line Items]
Debt issuance costs, net															$ 1,400,000
Revolving Credit Facility | 2019 Refinancing Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 25,000,000

Debt - 2019 ABL Agreement (Deta

Debt - 2019 ABL Agreement (Details) - USD ($)

Apr. 01, 2021

Oct. 01, 2019

Jul. 31, 2021

Mar. 31, 2020

Jun. 30, 2019

Jun. 30, 2021

Jun. 30, 2020

Jun. 30, 2021

Jun. 30, 2020

Sep. 30, 2020

Feb. 24, 2021

Dec. 31, 2020

Nov. 30, 2019

Debt Instrument [Line Items]

Amortization of debt issuance costs

$ 220,000

$ 1,080,000

2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Debt effective interest rate

5.25%

5.25%

5.25%

Leverage ratio

200.00%

330.00%

425.00%

Debt issuance costs, net

$ 900,000

Amortization of debt issuance costs

$ 0

$ 100,000

$ 100,000

$ 100,000

2019 Refinancing Revolving Credit Facility | Forecast

Debt Instrument [Line Items]

Leverage ratio

175.00%

2019 ABL Credit Amendment Number One and Waiver

Debt Instrument [Line Items]

Leverage ratio

200.00%

330.00%

425.00%

Lender's approval for acquisition, percentage

50.10%

Debt instrument, liquidity of loan parties

$ 10,000,000

Debt instrument, non refundable waiver fee

$ 7,500

Minimum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Unused line fee percentage

0.25%

Maximum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Unused line fee percentage

0.375%

Leverage ratio

400.00%

LIBOR Rate | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

2.00%

LIBOR Rate | Minimum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

3.00%

LIBOR Rate | Maximum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

3.50%

Base Rate | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

3.00%

Base Rate | Minimum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

2.00%

Base Rate | Maximum | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

2.50%

Revolving Credit Facility | 2019 Refinancing Revolving Credit Facility

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

15,000,000

$ 15,000,000

Line of credit facility, current borrowing capacity

14,000,000

14,000,000

Line of credit facility reserved borrowing capacity

$ 1,000,000

$ 1,000,000

Debt - Wintrust Term and Revolv

Debt - Wintrust Term and Revolving Loans (Details)	Feb. 24, 2021USD ($)covenant	Jun. 30, 2021USD ($)
Loans
Debt Instrument [Line Items]
Aggregate amount of unfinanced capital expenditures during any fiscal year	$ 0
Limit annual percentage of unfinanced capital expenditures	50.00%
Loans | Through December 31, 2021
Debt Instrument [Line Items]
Number of financial covenants | covenant	3
Leverage ratio	225.00%
Loans | All times thereafter
Debt Instrument [Line Items]
Leverage ratio	200.00%
Loans | As of the last day of each fiscal quarter commencing with the fiscal quarter ending March 31, 2021
Debt Instrument [Line Items]
Leverage ratio	120.00%
Loans | Maximum
Debt Instrument [Line Items]
Aggregate amount of unfinanced capital expenditures during any fiscal year	$ 4,000,000
Wintrust Term Loan
Debt Instrument [Line Items]
Debt effective interest rate		4.25%
Letters of credit		$ 3,400,000
Wintrust Revolving Loan
Debt Instrument [Line Items]
Debt effective interest rate		3.75%
Secured Debt | Wintrust Term Loan
Debt Instrument [Line Items]
Debt issued	30,000,000
Debt installment payments	$ 500,000
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | LIBOR Rate
Debt Instrument [Line Items]
Step-down adjustment on basis spread on variable rate	0.50%
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | LIBOR Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | LIBOR Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	4.00%
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | Base Rate
Debt Instrument [Line Items]
Step-down adjustment on basis spread on variable rate	0.75%
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	3.00%
Line of Credit | Revolving Credit Facility | Wintrust Term Loan | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000,000
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan | LIBOR Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan | LIBOR Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	3.50%
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan | Base Rate
Debt Instrument [Line Items]
Step-down adjustment on basis spread on variable rate	0.50%
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	3.00%
Line of Credit | Revolving Credit Facility | Wintrust Revolving Loan | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Line of Credit | Sublimit for Letters of Credit | Wintrust Revolving Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 5,000,000

Debt - Additional Margin and Co

Debt - Additional Margin and Commitment Fees Payable (Details)	6 Months Ended
	Jun. 30, 2021
Level I
Debt Instrument [Line Items]
Senior Leverage Ratio	100.00%
Commitment Fee	0.25%
Level I | Prime Rate | Wintrust Term Loan
Debt Instrument [Line Items]
Additional Margin for Loans	1.00%
Level I | Prime Rate | Wintrust Revolving Loan
Debt Instrument [Line Items]
Additional Margin for Loans	0.50%
Level I | Eurodollar | Wintrust Term Loan
Debt Instrument [Line Items]
Additional Margin for Loans	4.00%
Level I | Eurodollar | Wintrust Revolving Loan
Debt Instrument [Line Items]
Additional Margin for Loans	3.50%
Level II
Debt Instrument [Line Items]
Senior Leverage Ratio	100.00%
Commitment Fee	0.25%
Level II | Prime Rate | Wintrust Term Loan
Debt Instrument [Line Items]
Additional Margin for Loans	0.25%
Level II | Prime Rate | Wintrust Revolving Loan
Debt Instrument [Line Items]
Additional Margin for Loans	0.00%
Level II | Eurodollar | Wintrust Term Loan
Debt Instrument [Line Items]
Additional Margin for Loans	3.50%
Level II | Eurodollar | Wintrust Revolving Loan
Debt Instrument [Line Items]
Additional Margin for Loans	3.00%

Equity - Narrative (Details)

Equity - Narrative (Details) - USD ($)	Mar. 09, 2021	Feb. 18, 2021	Feb. 12, 2021	May 24, 2020	Jan. 01, 2020	Jan. 31, 2021	Jul. 31, 2020	Jun. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock, shares authorized (in shares)								100,000,000	100,000,000
Common stock, par or stated value per share (in usd per share)								$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)								1,000,000
Preferred stock, par or stated value per share (in usd per shares)								$ 0.0001
Offering
Class of Stock [Line Items]
Number of shares sold (in shares)			1,783,500
Share price (in usd per share)			$ 12
Proceeds from sale of shares, net of underwriters discounts and commissions			$ 19,800,000
Over-allotment Option
Class of Stock [Line Items]
Number of shares sold (in shares)			267,525
Share price (in usd per share)			$ 11.28
Period to purchase additional shares			30 days
Proceeds from sale of shares, net of underwriters discounts and commissions		$ 3,000,000
$15 Exercise Price Sponsor Warrants
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)								$ 15	$ 15
Omnibus Incentive Plan 2019
Class of Stock [Line Items]
Number of additional shares authorized under share-based compensation plan (in shares)	600,000			500,000
Common stock, capital shares reserved for future issuance (in shares)	2,250,000			1,650,000
ESPP | Employee Stock
Class of Stock [Line Items]
Purchase price of common stock, percent of market price (no less than)					85.00%
Maximum employee subscription percentage					10.00%
Maximum contribution amount					$ 5,000
Offering period					6 months
Discount percentage from market price, beginning of purchase period					15.00%
Award vesting period					6 months
Number of shares authorized (in shares)					500,000
Shares issued (in shares)						8,928	30,825

Equity - Outstanding Warrants (

Equity - Outstanding Warrants (Details) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	4,403,930	4,576,799
Public Warrants
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	2,140,219	2,300,000
Class of warrant or right, number of securities called by each warrant or right (in shares)	0.50	0.50
Class of warrant or right, rights for half share (in usd per share)	$ 5.75	$ 5.75
Exercise price of warrants (in usd per share)	$ 11.50	$ 11.50
Private Warrants
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	99,000	99,000
Class of warrant or right, number of securities called by each warrant or right (in shares)	0.50	0.50
Class of warrant or right, rights for half share (in usd per share)	$ 5.75	$ 5.75
Exercise price of warrants (in usd per share)	$ 11.50	$ 11.50
$15 Exercise Price Sponsor Warrants
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	600,000	600,000
Class of warrant or right, number of securities called by each warrant or right (in shares)	1	1
Exercise price of warrants (in usd per share)	$ 15	$ 15
Merger Warrants
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	629,643	631,119
Class of warrant or right, number of securities called by each warrant or right (in shares)	1	1
Exercise price of warrants (in usd per share)	$ 12.50	$ 12.50
Additional Merger Warrants
Class of Stock [Line Items]
Class of warrant or right, outstanding (in shares)	935,068	946,680
Class of warrant or right, number of securities called by each warrant or right (in shares)	1	1
Exercise price of warrants (in usd per share)	$ 11.50	$ 11.50

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Feb. 24, 2021	Dec. 31, 2020
2019 Refinancing Revolving Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Outstanding borrowings under credit agreement	$ 0	$ 0
Secured Debt | 2019 Refinancing Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 39,000,000	$ 39,000,000

Earnings per Share - Schedule o

Earnings per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
EPS numerator:
Net (loss) income	$ 732	$ (2,282)	$ 2,947	$ (52)	$ (1,550)	$ 2,895
EPS denominator:
Weighted average shares outstanding - basic (in shares)	10,251,696		7,845,515		9,737,801	7,821,594
Impact of dilutive securities (in shares)	217,000		59,000		0	56,000
Weighted average shares outstanding - diluted (in shares)	10,469,028		7,905,368		9,737,801	7,878,246
EPS:
Basic (in usd per share)	$ 0.07		$ 0.38		$ (0.16)	$ 0.37
Diluted (in usd per share)	$ 0.07		$ 0.37		$ (0.16)	$ 0.37

Earnings per Share - Schedule_2

Earnings per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	4,418,193	4,586,936	4,630,799	4,578,054
In-the-money warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	0	0	0
Out-of-the-money warrants (see Note 8)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	4,403,930	4,576,799	4,403,930	4,576,799
Service-based RSUs (See Note 17)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	334	463	142,120	1,255
Performance and market-based RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	13,929	9,674	79,971	0
Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	0	4,778	0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	26.50%	27.40%	33.20%	14.10%
Valuation allowance	$ 0		$ 0		$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 0	$ 1,130
Gross increases in prior period tax positions	0	0
Gross increases in current period tax positions	0	0
Decreases related to prior year tax positions	0	(1,130)
Balance at end of period	$ 0	$ 0

Operating Segments - Narrative

Operating Segments - Narrative (Details)	6 Months Ended
	Jun. 30, 2021approachsegment
Segment Reporting Information [Line Items]
Number of operating segments	2
Number of reportable segments	2
Number distinct approaches to customer base | approach	2
GCR
Segment Reporting Information [Line Items]
Number of reportable segments	1
ODR
Segment Reporting Information [Line Items]
Number of reportable segments	1

Operating Segments - Condensed

Operating Segments - Condensed Consolidated Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenue	$ 121,019	$ 135,185	$ 234,363	$ 273,957
Gross profit	18,690	20,335	35,919	38,559
Selling, general and administrative	17,232	13,752	34,377	30,552
Amortization of intangibles	104	274	208	417
Operating income	1,354	6,309	1,334	7,590
Interest expense, net	(452)	(2,137)	(1,716)	(4,295)
Gain on sale of property and equipment	94	(13)	8	17
Loss on early debt extinguishment	0	0	(1,961)	0
Gain (loss) on change in fair value of warrant liability	0	(102)	14	59
Total unallocated amounts	(358)	(2,252)	(3,655)	(4,219)
Income (loss) before income taxes	996	4,057	(2,321)	3,371
Depreciation and amortization	1,469	1,636	2,964	3,140
Selling, general and administrative	16,596	13,612	33,064	30,117
EBIT	2,094	6,723	2,855	8,442
GCR
Segment Reporting Information [Line Items]
Revenue	87,550	105,937
Gross profit	8,885	12,213
Selling, general and administrative	9,070	8,024
ODR
Segment Reporting Information [Line Items]
Revenue	33,469	29,248
Gross profit	9,805	8,122
Selling, general and administrative	7,526	5,588
Operating Segments
Segment Reporting Information [Line Items]
Gross profit	18,690	20,335	35,919	38,559
Operating Segments | GCR
Segment Reporting Information [Line Items]
Revenue	87,550	105,937	172,354	215,423
Gross profit	8,885	12,213	18,280	23,195
Selling, general and administrative	9,070	8,024	18,184	18,200
Depreciation and amortization	1,020	1,032	2,056	2,062
Selling, general and administrative			18,184	18,200
EBIT	(185)	4,189	96	4,995
Operating Segments | ODR
Segment Reporting Information [Line Items]
Revenue	33,469	29,248	62,009	58,534
Gross profit	9,805	8,122	17,639	15,364
Selling, general and administrative	7,526	5,588	14,880	11,917
Depreciation and amortization	345	330	700	661
Selling, general and administrative			14,880	11,917
EBIT	2,279	2,534	2,759	3,447
Corporate
Segment Reporting Information [Line Items]
Selling, general and administrative	636	140	1,313	435
Depreciation and amortization	$ 104	$ 274	$ 208	$ 417

Operating Segments - Reconcilia

Operating Segments - Reconciliation of Segment Gross Profit to Consolidated Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Gross profit	$ 18,690	$ 20,335	$ 35,919	$ 38,559
Selling, general and administrative	(17,232)	(13,752)	(34,377)	(30,552)
Amortization of intangibles	(104)	(274)	(208)	(417)
Total other expenses	358	2,252	3,655	4,219
Income (loss) before income taxes	996	4,057	(2,321)	3,371
Operating Segments
Segment Reporting Information [Line Items]
Gross profit	18,690	20,335	35,919	38,559
Segment Reconciling Items
Segment Reporting Information [Line Items]
Selling, general and administrative	(17,232)	(13,752)	(34,377)	(30,552)
Amortization of intangibles	(104)	(274)	(208)	(417)
Total other expenses	$ (358)	$ (2,252)	$ (3,655)	$ (4,219)

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheets Information (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 16,852	$ 18,751
Property, plant and equipment, net	5,251	6,242
Lease right-of-use assets	22,103	24,993
Current operating lease liabilities	4,122	3,929
Current portion of long-term debt	2,454	2,536
Long-term operating lease liabilities	13,454	15,459
Long-term debt	3,022	3,923
Total lease liabilities	23,052	25,847
Operating lease, accumulated amortization	13,900	11,900
Finance lease, accumulated amortization	$ 5,600	$ 5,300

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lessee, Lease, Description [Line Items]
Finance lease cost, amortization	$ 652,000	$ 645,000	$ 1,327,000	$ 1,311,000
Finance lease cost, interest expense	78,000	86,000	164,000	179,000
Total lease cost	1,999,000	2,000,000	4,035,000	4,024,000
Cost of revenue
Lessee, Lease, Description [Line Items]
Operating lease cost	685,000	893,000	1,375,000	1,777,000
Cost of revenue | Operating Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	100,000	100,000	200,000	400,000
Cost of revenue | Finance Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	700,000	500,000	1,300,000	1,200,000
Selling, general and administrative expenses
Lessee, Lease, Description [Line Items]
Operating lease cost	584,000	376,000	1,169,000	757,000
Selling, general and administrative expenses | Operating Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	100,000	100,000	200,000	100,000
Selling, general and administrative expenses | Finance Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	$ 0	$ 0	$ 0	$ 0

Leases - Future Minimum Lease C

Leases - Future Minimum Lease Commitment (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Finance Leases
Remainder of 2021	$ 1,401
2022	2,404
2023	1,409
2024	598
2025	50
Thereafter	0
Total minimum lease payments	5,862
Amounts representing interest	(386)
Present value of net minimum lease payments	5,476	$ 6,459
Operating Leases
Remainder of 2021	2,479
2022	4,616
2023	3,516
2024	2,917
2025	2,409
Thereafter	4,043
Total minimum lease payments	$ 19,980

Leases - Summary of Lease Terms

Leases - Summary of Lease Terms and Discount Rates (Details)	Jun. 30, 2021	Dec. 31, 2020
Leases [Abstract]
Operating leases, weighted average remaining lease term	5 years 1 month 24 days	5 years 5 months 23 days
Finance leases, weighted average remaining lease term	2 years 5 months 26 days	2 years 9 months 10 days
Operating leases, weighted average remaining discount rate	4.84%	4.83%
Finance leases, weighted average remaining discount rate	5.45%	5.50%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating cash flows from operating leases	$ 2,456	$ 2,910
Operating cash flows from finance leases	164	179
Financing cash flows from finance leases	1,318	1,285
Right of use assets obtained in exchange for new operating lease liabilities	156	0
Right of use assets obtained in exchange for new finance lease liabilities	336	1,050
Right-of-use assets disposed or adjusted modifying operating leases liabilities	36	586
Right-of-use assets disposed or adjusted modifying finance leases liabilities	$ 0	$ (64)

Self-Insurance - Narrative (Det

Self-Insurance - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Insurance [Abstract]
Payment to acquire workers' compensation and general liability insurance	$ 250
Malpractice insurance, annual coverage limit	$ 4,400

Self-Insurance - Components of

Self-Insurance - Components of Self-Insurance (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Insurance [Abstract]
Current liability — workers’ compensation and general liability	$ 105	$ 197
Current liability — medical and dental	511	764
Non-current liability	776	890
Total liability shown in Accrued expenses and other current liabilities	1,392	1,851
Restricted cash	$ 113	$ 113

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Apr. 17, 2020	Jan. 23, 2020	Nov. 13, 2019	Jul. 31, 2020	Jun. 30, 2021
Surety Bond
Loss Contingencies [Line Items]
Debt outstanding					$ 265.3
Lanzo Trenchless Technologies vs. Limbach Company LLC | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, value			$ 0.4
Bernards Bros vs. Limbach Holdings, Inc. | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, value		$ 3
LA Excavating, Inc. vs. Limbach Company LP | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, value	$ 1
Kimball Construction Co., Inc. vs. Limbach Company LLC | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, value				$ 1.7

Remaining Performance Obligat_2

Remaining Performance Obligations (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligations, expected timing of satisfaction, period	24 months
GCR
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, amount	$ 378.9	$ 393.5
GCR | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligations, percentage	44.00%
Revenue, remaining performance obligations, expected timing of satisfaction, period	6 months
GCR | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligations, percentage	56.00%
Revenue, remaining performance obligations, expected timing of satisfaction, period	1 year 6 months
ODR
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, amount	$ 44.2	$ 35.7
ODR | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligations, percentage	62.00%
Revenue, remaining performance obligations, expected timing of satisfaction, period	6 months
ODR | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligations, percentage	38.00%
Revenue, remaining performance obligations, expected timing of satisfaction, period	1 year 6 months

Management Incentive Plans - Na

Management Incentive Plans - Narrative (Details) - USD ($) $ in Thousands	Sep. 04, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 09, 2021	May 24, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation				$ 1,313	$ 435
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted (in shares)				120,899
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted (in shares)				185,367
MRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted (in shares)				0
Unrecognized share-based costs	$ 200
Weighted average period to recognize share-based costs	1 year 3 months 3 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized stock-based compensation		$ 700	$ 100	$ 1,300	400
Unrecognized share-based costs		3,600		$ 3,600
Weighted average period to recognize share-based costs				2 years
Fair value of awards vested				$ 1,300	600
Omnibus Incentive Plan 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)						2,250,000	1,650,000
Omnibus Incentive Plan 2019 | PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted (in shares)				185,367
Recognized stock-based compensation		$ 200	$ 100	$ 400	$ 100

Management Incentive Plans - RS

Management Incentive Plans - RSUs Activity (Details) - RSUs	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Awards
Unvested at December 31, 2020 (in shares) | shares	285,799
Granted, awards (in shares) | shares	120,899
Vested, awards (in shares) | shares	(106,383)
Forfeited, awards (in shares) | shares	(2,333)
Unvested at March 31, 2021 (in shares) | shares	297,982
Weighted-Average Grant Date Fair Value
Unvested at December 31, 2020 (usd per share) | $ / shares	$ 6.32
Granted, weighted-average grant date fair values (usd per share) | $ / shares	12.25
Vested, weighted-average grant date fair values (usd per share) | $ / shares	6.66
Forfeited, weighted-average grant date fair values (usd per share) | $ / shares	8.27
Unvested at March 31, 2021 (usd per share) | $ / shares	$ 8.59

Management Incentive Plans - PR

Management Incentive Plans - PRSUs Activity (Details) - PRSUs	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Awards
Unvested at December 31, 2020 (in shares) | shares	99,500
Granted, awards (in shares) | shares	185,367
Vested, awards (in shares) | shares	0
Forfeited, awards (in shares) | shares	(4,167)
Unvested at March 31, 2021 (in shares) | shares	280,700
Weighted-Average Grant Date Fair Value
Unvested at December 31, 2020 (usd per share) | $ / shares	$ 4.23
Granted, weighted-average grant date fair values (usd per share) | $ / shares	12.26
Vested, weighted-average grant date fair values (usd per share) | $ / shares	0
Forfeited, weighted-average grant date fair values (usd per share) | $ / shares	8.92
Unvested at March 31, 2021 (usd per share) | $ / shares	$ 9.46

Management Incentive Plans - MR

Management Incentive Plans - MRSUs Activity (Details) - MRSUs	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Awards
Unvested at December 31, 2020 (in shares) | shares	102,500
Granted, awards (in shares) | shares	0
Vested, awards (in shares) | shares	0
Forfeited, awards (in shares) | shares	0
Unvested at March 31, 2021 (in shares) | shares	102,500
Weighted-Average Grant Date Fair Value
Unvested at December 31, 2020 (usd per share) | $ / shares	$ 8.26
Granted, weighted-average grant date fair values (usd per share) | $ / shares	0
Vested, weighted-average grant date fair values (usd per share) | $ / shares	0
Forfeited, weighted-average grant date fair values (usd per share) | $ / shares	0
Unvested at March 31, 2021 (usd per share) | $ / shares	$ 8.26