EXECUTION COPY

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EXHIBIT 10.7

GUARANTEE AGREEMENT

dated as of

August 2, 2006

among

USG CORPORATION,

THE SUBSIDIARIES OF USG CORPORATION
IDENTIFIED HEREIN

and

JPMORGAN CHASE BANK, N.A.,

as Administrative Agent

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TABLE OF CONTENTS

ARTICLE I

Definitions

SECTION 1.01. Credit Agreement............................................ 1
SECTION 1.02. Other Defined Terms......................................... 1

ARTICLE II

Guarantee

SECTION 2.01. Guarantee................................................... 2
SECTION 2.02. Guarantee of Payment........................................ 2
SECTION 2.03. No Limitations.............................................. 3
SECTION 2.04. Reinstatement............................................... 3
SECTION 2.05. Agreement To Pay; Subrogation............................... 3
SECTION 2.06. Information................................................. 4

ARTICLE III

Indemnity, Subrogation and Subordination

SECTION 3.01. Indemnity and Subrogation................................... 4
SECTION 3.02. Contribution and Subrogation................................ 4
SECTION 3.03. Subordination............................................... 4

ARTICLE IV

Miscellaneous

SECTION 4.01. Notices..................................................... 5
SECTION 4.02. Waivers; Amendment.......................................... 5
SECTION 4.03. Administrative Agent's Fees and Expenses; Indemnification... 5
SECTION 4.04. Successors and Assigns...................................... 6
SECTION 4.05. Survival of Agreement....................................... 6
SECTION 4.06. Counterparts; Effectiveness; Several Agreement.............. 7
SECTION 4.07. Severability................................................ 7
SECTION 4.08. Right of Set-Off............................................ 7
SECTION 4.09. Governing Law; Jurisdiction; Consent to Service of Process.. 7
SECTION 4.10. WAIVER OF JURY TRIAL........................................ 8
SECTION 4.11. Headings.................................................... 8
SECTION 4.12. Guarantee Absolute.......................................... 9
SECTION 4.13. Termination or Release...................................... 9
SECTION 4.14. Additional Subsidiaries..................................... 9

Schedules

Schedule I Guarantors

Exhibits

Exhibit I Form of Supplement

GUARANTEE AGREEMENT dated as of August 2, 2006 among USG
CORPORATION, the Subsidiaries of USG CORPORATION identified
herein and JPMORGAN CHASE BANK, N.A., as Administrative Agent.

Reference is made to the Credit Agreement dated as of August 2, 2006
(as amended, supplemented or otherwise modified from time to time, the "CREDIT
AGREEMENT"), among USG Corporation, a Delaware corporation (the "BORROWER"), the
Lenders party thereto, JPMorgan Chase Bank, N.A., as Administrative Agent and
Goldman Sachs Credit Partners L.P., as Syndication Agent. The Lenders have
agreed to extend credit to the Borrower subject to the terms and conditions set
forth in the Credit Agreement. The obligations of the Lenders to extend such
credit are conditioned upon, among other things, the execution and delivery of
this Agreement. The Subsidiary Parties are affiliates of the Borrower, will
derive substantial benefits from the extension of credit to the Borrower
pursuant to the Credit Agreement and are willing to execute and deliver this
Agreement in order to induce the Lenders to extend such credit. Accordingly, the
parties hereto agree as follows:

ARTICLE I

Definitions

SECTION 1.01. Credit Agreement. (a) Capitalized terms used in this
Agreement and not otherwise defined herein have the meanings specified in the
Credit Agreement.

(b) The rules of construction specified in Section 1.03 of the Credit
Agreement also apply to this Agreement.

SECTION 1.02. Other Defined Terms. As used in this Agreement, the
following terms have the meanings specified below:

"BORROWER" has the meaning assigned to such term in the preliminary
statement of this Agreement.

"CLAIMING PARTY" has the meaning assigned to such term in Section
3.02.

"CONTRIBUTING PARTY" has the meaning assigned to such term in Section
3.02.

"CREDIT AGREEMENT" has the meaning assigned to such term in the
preliminary statement of this Agreement.

"GUARANTEED PARTIES" means (a) the Lenders, (b) the Administrative
Agent, (c) the Issuing Bank, (d) the beneficiaries of each indemnification
obligation undertaken by any Loan Party under any Loan Document and (e) the
permitted successors and assigns of each of the foregoing.

"GUARANTORS" means (a) the Subsidiaries identified on Schedule I and
(b) each other Subsidiary that becomes a party to this Agreement after the
Effective Date.

"OBLIGATIONS" means (a) the due and punctual payment by the Borrower
of (i) the principal of and interest (including interest accruing during the
pendency of any bankruptcy, insolvency, receivership or other similar
proceeding, regardless of whether allowed or allowable in such proceeding) on
the Loans, when and as due, whether at maturity, by acceleration, upon one or
more dates set for prepayment or otherwise, (ii) each payment required to be
made by the Borrower under the Credit Agreement in respect of any Letter of
Credit, when and as due, including payments in respect of reimbursement of
disbursements, interest thereon and obligations to provide cash collateral, and
(iii) all other monetary obligations of the Borrower to any of the Guaranteed
Parties under the Credit Agreement and each of the other Loan Documents,
including obligations to pay fees, expense reimbursement obligations and
indemnification obligations, whether primary, secondary, direct, contingent,
fixed or otherwise (including monetary obligations incurred during the pendency
of any bankruptcy, insolvency, receivership or other similar proceeding,
regardless of whether allowed or allowable in such proceeding), (b) the due and
punctual performance of all other obligations of the Borrower under or pursuant
to the Credit Agreement and each of the other Loan Documents and (c) the due and
punctual payment and performance of all the obligations of each other Loan Party
under or pursuant to this Agreement and each of the other Loan Documents.

ARTICLE II

Guarantee

SECTION 2.01. Guarantee. Each Guarantor unconditionally guarantees,
jointly with the other Guarantors and severally, as a primary obligor and not
merely as a surety, the due and punctual payment and performance of the
Obligations. Each of the Guarantors further agrees that the Obligations may be
extended or renewed, in whole or in part, without notice to or further assent
from it, and that it will remain bound upon its guarantee notwithstanding any
extension or renewal of any Obligation. Each of the Guarantors waives
presentment to, demand of payment from and protest to the Borrower or any other
Loan Party of any of the Obligations, and also waives notice of acceptance of
its guarantee and notice of protest for nonpayment.

SECTION 2.02. Guarantee of Payment. Each of the Guarantors further
agrees that its guarantee hereunder constitutes a guarantee of payment when due
and not of collection, and waives any right to require that any resort be had by
the Administrative Agent or any other Guaranteed Party to any security held for
the payment of the Obligations or to any balance of any deposit account or
credit on the books of the Administrative Agent or any other Guaranteed Party in
favor of the Borrower or any other Person.

SECTION 2.03. No Limitations. (a) Except for termination of a
Guarantor's obligations hereunder as expressly provided in Section 4.13, the
obligations of each Guarantor hereunder shall not be subject to any reduction,
limitation, impairment or termination for any reason, including any claim of
waiver, release, surrender, alteration or compromise, and shall not be subject
to any defense or set-off, counterclaim, recoupment or termination whatsoever by
reason of the invalidity, illegality or unenforceability of the Obligations or
otherwise. Without limiting the generality of the foregoing, the obligations of
each Guarantor hereunder shall not be discharged or impaired or otherwise
affected by (i) the failure of the Administrative Agent or any other Guaranteed
Party to assert any claim or demand or to enforce any right or remedy under the
provisions of any Loan Document or otherwise; (ii) any rescission, waiver,
amendment or modification of, or any release from any of the terms or provisions
of, any Loan Document or any other agreement, including with respect to any
other Guarantor under this Agreement; (iii) the release of any security, if any,
held by the Administrative Agent or any other Guaranteed Party for the
Obligations or any of them; (iv) any default, failure or delay, wilful or
otherwise, in the performance of the Obligations; or (v) any other act or
omission that may or might in any manner or to any extent vary the risk of any
Guarantor or otherwise operate as a discharge of any Guarantor as a matter of
law or equity (other than the payment in full in cash of all the Obligations).

(b) To the fullest extent permitted by applicable law, each Guarantor
waives any defense based on or arising out of any defense of the Borrower or any
other Loan Party or the unenforceability of the Obligations or any part thereof
from any cause, or the cessation from any cause of the liability of the Borrower
or any other Loan Party, other than the payment in full in cash of all the
Obligations. The Administrative Agent may, at its election, foreclose on any
security held by it by one or more judicial or nonjudicial sales, accept an
assignment of any such security in lieu of foreclosure, compromise or adjust any
part of the Obligations, make any other accommodation with the Borrower or any
other Loan Party or exercise any other right or remedy available to them against
the Borrower or any other Loan Party, without affecting or impairing in any way
the liability of any Guarantor hereunder except to the extent the Obligations
have been paid in full in cash. To the fullest extent permitted by applicable
law, each Guarantor waives any defense arising out of any such election even
though such election may operate, pursuant to applicable law, to impair or to
extinguish any right of reimbursement or subrogation or other right or remedy of
such Guarantor against the Borrower or any other Loan Party, as the case may be,
or any security.

SECTION 2.04. Reinstatement. Each of the Guarantors agrees that its
guarantee hereunder shall continue to be effective or be reinstated, as the case
may be, if at any time payment, or any part thereof, of any Obligation is
rescinded or must otherwise be restored by the Administrative Agent or any other
Guaranteed Party upon the bankruptcy or reorganization of the Borrower, any
other Loan Party or otherwise.

SECTION 2.05. Agreement To Pay; Subrogation. In furtherance of the
foregoing and not in limitation of any other right that the Administrative Agent
or any other Guaranteed Party has at law or in equity against any Guarantor by
virtue hereof, upon the failure of the Borrower or any other Loan Party to pay
any Obligation when and

as the same shall become due, whether at maturity, by acceleration, after notice
of prepayment or otherwise, each Guarantor hereby promises to and will forthwith
pay, or cause to be paid, to the Administrative Agent for distribution to the
applicable Guaranteed Parties in cash the amount of such unpaid Obligation. Upon
payment by any Guarantor of any sums to the Administrative Agent as provided
above, all rights of such Guarantor against the Borrower or any other Loan Party
arising as a result thereof by way of right of subrogation, contribution,
reimbursement, indemnity or otherwise shall in all respects be subject to
Article III.

SECTION 2.06. Information. Each Guarantor assumes all responsibility
for being and keeping itself informed of the Borrower's and each other Loan
Party's financial condition and assets, and of all other circumstances bearing
upon the risk of nonpayment of the Obligations and the nature, scope and extent
of the risks that such Guarantor assumes and incurs hereunder, and agrees that
none of the Administrative Agent or the other Guaranteed Parties will have any
duty to advise such Guarantor of information known to it or any of them
regarding such circumstances or risks.

ARTICLE III

Indemnity, Subrogation and Subordination

SECTION 3.01. Indemnity and Subrogation. In addition to all such
rights of indemnity and subrogation as the Guarantors may have under applicable
law (but subject to Section 3.03), the Borrower agrees that in the event a
payment of an obligation shall be made by any Guarantor under this Agreement,
the Borrower shall indemnify such Guarantor for the full amount of such payment
and such Guarantor shall be subrogated to the rights of the Person to whom such
payment shall have been made to the extent of such payment.

SECTION 3.02. Contribution and Subrogation. Each Guarantor (a
"CONTRIBUTING PARTY") agrees (subject to Section 3.03) that, in the event a
payment shall be made by any other Guarantor hereunder in respect of any
Obligation and such other Guarantor (the "CLAIMING PARTY") shall not have been
fully indemnified by the Borrower as provided in Section 3.01, the Contributing
Party shall indemnify the Claiming Party in an amount equal to the amount of
such payment multiplied by a fraction of which the numerator shall be the net
worth of the Contributing Party on the date hereof and the denominator shall be
the aggregate net worth of all the Guarantors on the date hereof (or, in the
case of any Guarantor becoming a party hereto pursuant to Section 4.14, the date
of the supplement hereto executed and delivered by such Guarantor). Any
Contributing Party making any payment to a Claiming Party pursuant to this
Section 3.02 shall be subrogated to the rights of such Claiming Party under
Section 3.01 to the extent of such payment.

SECTION 3.03. Subordination. (a) Notwithstanding any provision of this
Agreement to the contrary, all rights of the Guarantors under Sections 3.01 and
3.02 and all other rights of indemnity, contribution or subrogation under
applicable law or otherwise shall be fully subordinated to the payment in full
in cash of the Obligations.

No failure on the part of the Borrower or any Guarantor to make the payments
required by Sections 3.01 and 3.02 (or any other payments required under
applicable law or otherwise) shall in any respect limit the obligations and
liabilities of any Guarantor with respect to its obligations hereunder, and each
Guarantor shall remain liable for the full amount of the obligations of such
Guarantor hereunder.

(b) Each Guarantor hereby agrees that all Indebtedness owed by it to
any other Subsidiary that is not a Subsidiary Loan Party shall be fully
subordinated to the payment in full in cash of the Obligations.

ARTICLE IV

Miscellaneous

SECTION 4.01. Notices. All communications and notices hereunder shall
(except as otherwise expressly permitted herein) be in writing and given as
provided in Section 9.01 of the Credit Agreement. All communications and notices
hereunder to any Guarantor shall be given to it in care of the Borrower as
provided in Section 9.01 of the Credit Agreement.

SECTION 4.02. Waivers; Amendment. (a) No failure or delay by the
Administrative Agent, the Issuing Bank or any Lender in exercising any right or
power hereunder or under any other Loan Document shall operate as a waiver
thereof, nor shall any single or partial exercise of any such right or power, or
any abandonment or discontinuance of steps to enforce such a right or power,
preclude any other or further exercise thereof or the exercise of any other
right or power. The rights and remedies of the Administrative Agent, the Issuing
Bank and the Lenders hereunder and under the other Loan Documents are cumulative
and are not exclusive of any rights or remedies that they would otherwise have.
No waiver of any provision of this Agreement or consent to any departure by any
Loan Party therefrom shall in any event be effective unless the same shall be
permitted by paragraph (b) of this Section 4.02, and then such waiver or consent
shall be effective only in the specific instance and for the purpose for which
given. Without limiting the generality of the foregoing, the making of a Loan or
issuance of a Letter of Credit shall not be construed as a waiver of any
Default, regardless of whether the Administrative Agent, any Lender or the
Issuing Bank may have had notice or knowledge of such Default at the time. No
notice or demand on any Loan Party in any case shall entitle any Loan Party to
any other or further notice or demand in similar or other circumstances.

(b) Neither this Agreement nor any provision hereof may be waived,
amended or modified except pursuant to an agreement or agreements in writing
entered into by the Administrative Agent and the Loan Party or Loan Parties with
respect to which such waiver, amendment or modification is to apply, subject to
any consent required in accordance with Section 9.02 of the Credit Agreement.

SECTION 4.03. Administrative Agent's Fees and Expenses;
Indemnification. (a) The parties hereto agree that the Administrative Agent
shall be

entitled to reimbursement of its expenses incurred hereunder as provided in
Section 9.03 of the Credit Agreement.

(b) Without limitation of its indemnification obligations under the
other Loan Documents, each Guarantor jointly and severally agrees to indemnify
the Administrative Agent and the other Indemnitees (as defined in Section 9.03
of the Credit Agreement) against, and hold each Indemnitee harmless from, any
and all out-of-pocket losses, claims, damages, liabilities and related
reasonable expenses, including the reasonable fees, charges and disbursements of
any counsel for any Indemnitee, incurred by or asserted against any Indemnitee
arising out of, in connection with, or as a result of, the execution, delivery
or performance of this Agreement or any claim, litigation, investigation or
proceeding relating to this Agreement or any instrument contemplated hereby,
whether or not any Indemnitee is a party thereto; provided that such indemnity
shall not, as to any Indemnitee, be available to the extent that such losses,
claims, damages, liabilities or related expenses are determined by a court of
competent jurisdiction by final and nonappealable judgment to have resulted from
the gross negligence or wilful misconduct of such Indemnitee.

(c) Any such amounts payable as provided hereunder shall be additional
Obligations guaranteed hereby. The provisions of this Section 4.03 shall remain
operative and in full force and effect regardless of the termination of this
Agreement or any other Loan Document, the consummation of the transactions
contemplated hereby, the repayment of any of the Obligations, the invalidity or
unenforceability of any term or provision of this Agreement or any other Loan
Document, or any investigation made by or on behalf of the Administrative Agent
or any other Guaranteed Party. All amounts due under this Section 4.03 shall be
payable not later than three Business Days after written demand therefor setting
forth the basis for such claim in reasonable detail.

SECTION 4.04. Successors and Assigns. Whenever in this Agreement any
of the parties hereto is referred to, such reference shall be deemed to include
the permitted successors and assigns of such party; and all covenants, promises
and agreements by or on behalf of any Guarantor or the Administrative Agent that
are contained in this Agreement shall bind and inure to the benefit of their
respective successors and assigns.

SECTION 4.05. Survival of Agreement. All covenants, agreements,
representations and warranties made by the Loan Parties in the Loan Documents
and in the certificates or other instruments prepared or delivered in connection
with or pursuant to this Agreement or any other Loan Document shall be
considered to have been relied upon by the Lenders and shall survive the
execution and delivery of the Loan Documents and the making of any Loans and
issuance of any Letters of Credit, regardless of any investigation made by any
Lender or on its behalf and notwithstanding that the Administrative Agent, the
Issuing Bank or any Lender may have had notice or knowledge of any Default or
incorrect representation or warranty at the time any credit is extended under
the Credit Agreement, and shall continue in full force and effect as long as the
principal of or any accrued interest on any Loan or any fee or any other amount
payable

under any Loan Document is outstanding and unpaid or any Letter of Credit is
outstanding and so long as the Commitments have not expired or terminated.

SECTION 4.06. Counterparts; Effectiveness; Several Agreement. This
Agreement may be executed in counterparts, each of which shall constitute an
original but all of which when taken together shall constitute a single
contract. Delivery of an executed signature page to this Agreement by facsimile
transmission shall be as effective as delivery of a manually signed counterpart
of this Agreement. This Agreement shall become effective as to any Loan Party
when a counterpart hereof executed on behalf of such Loan Party shall have been
delivered to the Administrative Agent and a counterpart hereof shall have been
executed on behalf of the Administrative Agent, and thereafter shall be binding
upon such Loan Party and the Administrative Agent and their respective permitted
successors and assigns, and shall inure to the benefit of such Loan Party, the
Administrative Agent and the other Guaranteed Parties and their respective
successors and assigns, except that no Loan Party shall have the right to assign
or transfer its rights or obligations hereunder or any interest herein (and any
such assignment or transfer shall be void) except as expressly contemplated by
this Agreement or the Credit Agreement. This Agreement shall be construed as a
separate agreement with respect to each Loan Party and may be amended, modified,
supplemented, waived or released with respect to any Loan Party without the
approval of any other Loan Party and without affecting the obligations of any
other Loan Party hereunder.

SECTION 4.07. Severability. Any provision of this Agreement held to be
invalid, illegal or unenforceable in any jurisdiction shall, as to such
jurisdiction, be ineffective to the extent of such invalidity, illegality or
unenforceability without affecting the validity, legality and enforceability of
the remaining provisions hereof; and the invalidity of a particular provision in
a particular jurisdiction shall not invalidate such provision in any other
jurisdiction. The parties shall endeavor in good-faith negotiations to replace
the invalid, illegal or unenforceable provisions with valid provisions the
economic effect of which comes as close as possible to that of the invalid,
illegal or unenforceable provisions.

SECTION 4.08. Right of Set-Off. If an Event of Default shall have
occurred and be continuing, each Lender and each of its Affiliates is hereby
authorized at any time and from time to time, to the fullest extent permitted by
law, to set off and apply any and all deposits (general or special, time or
demand, provisional or final) at any time held and other obligations at any time
owing by such Lender or Affiliate to or for the credit or the account of any
Guarantor against any of and all the obligations of such Guarantor now or
hereafter existing under this Agreement owed to such Lender, irrespective of
whether or not such Lender shall have made any demand under this Agreement and
although such obligations may be unmatured. The rights of each Lender under this
Section 4.08 are in addition to other rights and remedies (including other
rights of set-off) which such Lender may have.

SECTION 4.09. Governing Law; Jurisdiction; Consent to Service of
Process. (a) This Agreement shall be construed in accordance with and governed
by the law of the State of New York.

(b) Each of the parties hereto hereby irrevocably and unconditionally
submits, for itself and its property, to the exclusive jurisdiction of the
Supreme Court of the State of New York sitting in New York County and of the
United States District Court of the Southern District of New York, and any
appellate court from any thereof, in any action or proceeding arising out of or
relating to this Agreement or any other Loan Document, or for recognition or
enforcement of any judgment, and each of the parties hereto hereby irrevocably
and unconditionally agrees that all claims in respect of any such action or
proceeding may be heard and determined in such New York State or, to the extent
permitted by law, in such Federal court. Each of the parties hereto agrees that
a final judgment in any such action or proceeding shall be conclusive and may be
enforced in other jurisdictions by suit on the judgment or in any other manner
provided by law.

(c) Each of the parties hereto hereby irrevocably and unconditionally
waives, to the fullest extent it may legally and effectively do so, any
objection which it may now or hereafter have to the laying of venue of any suit,
action or proceeding arising out of or relating to this Agreement or any other
Loan Document in any court referred to in paragraph (b) of this Section 4.09.
Each of the parties hereto hereby irrevocably waives, to the fullest extent
permitted by law, the defense of an inconvenient forum to the maintenance of
such action or proceeding in any such court.

(d) Each party to this Agreement irrevocably consents to service of
process in the manner provided for notices in Section 4.01. Nothing in this
Agreement or any other Loan Document will affect the right of any party to this
Agreement to serve process in any other manner permitted by law.

SECTION 4.10. WAIVER OF JURY TRIAL. EACH PARTY HERETO HEREBY WAIVES,
TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A
TRIAL BY JURY IN ANY LEGAL PROCEEDING DIRECTLY OR INDIRECTLY ARISING OUT OF OR
RELATING TO THIS AGREEMENT, ANY OTHER LOAN DOCUMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY (WHETHER BASED ON CONTRACT, TORT OR ANY OTHER THEORY). EACH
PARTY HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY
OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD
NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER AND (B)
ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER
INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION 4.10.

SECTION 4.11. Headings. Article and Section headings and the Table of
Contents used herein are for convenience of reference only, are not part of this
Agreement and are not to affect the construction of, or to be taken into
consideration in interpreting, this Agreement.

SECTION 4.12. Guarantee Absolute. All rights of the Administrative
Agent hereunder and all obligations of each Guarantor hereunder shall be
absolute and unconditional irrespective of (a) any lack of validity or
enforceability of the Credit Agreement, any other Loan Document, any agreement
with respect to any of the Obligations or any other agreement or instrument
relating to any of the foregoing, (b) any change in the time, manner or place of
payment of, or in any other term of, all or any of the Obligations, or any other
amendment or waiver of or any consent to any departure from the Credit
Agreement, any other Loan Document or any other agreement or instrument, (c) any
release or amendment or waiver of or consent under or departure from any
guarantee guaranteeing all or any of the Obligations, or (d) any other
circumstance that might otherwise constitute a defense available to, or a
discharge of, any Guarantor in respect of the Obligations or this Agreement
(other than the payment in full, in cash, of the Obligations).

SECTION 4.13. Termination or Release. (a) This Agreement and the
Guarantees made herein shall terminate when all the Obligations have been paid
in full, in cash, and the Lenders have no further commitment to lend under the
Credit Agreement, the LC Exposure has been reduced to zero and the Issuing Bank
has no further obligations to issue Letters of Credit under the Credit
Agreement.

(b) A Guarantor shall automatically be released from its obligations
hereunder upon the consummation of any transaction permitted by the Credit
Agreement as a result of which such Guarantor ceases to be a Subsidiary of the
Borrower; provided that the Required Lenders shall have consented to such
transaction (to the extent required by the Credit Agreement) and the terms of
such consent did not provide otherwise.

(c) In connection with any termination or release pursuant to
paragraph (a) or (b) of this Section 4.13, the Administrative Agent shall
execute and deliver to any Guarantor, at such Guarantor's expense, all documents
that such Guarantor shall reasonably request to evidence such termination or
release. Any execution and delivery of documents pursuant to this Section 4.13
shall be without recourse to or warranty by the Administrative Agent.

SECTION 4.14. Additional Subsidiaries. Pursuant to Section 5.10 of the
Credit Agreement, each domestic Material Subsidiary of a Loan Party that was not
in existence or not a Material Subsidiary on the date of the Credit Agreement is
required to enter in this Agreement as a Guarantor upon becoming such a domestic
Material Subsidiary unless the Administrative Agent determines that the cost of
the satisfaction of the Guarantee Requirement with respect thereto exceeds the
value afforded hereby; provided that the terms of this Section 4.14 shall not be
required to be satisfied with respect to any SPE Subsidiary or any Subsidiary
that is subject to any legal or, in the case of any special purpose or limited
purpose entity, any contractual restriction preventing or prohibiting it from
satisfying the Guarantee Requirement. Upon execution and delivery by the
Administrative Agent and a Subsidiary of an instrument in the form of Exhibit I
hereto, such Subsidiary shall become a Guarantor hereunder with the same force
and effect as if originally named as a Guarantor herein. The execution and
delivery of any such instrument shall not require the consent of any other Loan
Party hereunder. The

rights and obligations of each Loan Party hereunder shall remain in full force
and effect notwithstanding the addition of any new Loan Party as a party to this
Agreement.

IN WITNESS WHEREOF, the parties hereto have duly executed this
Agreement as of the day and year first above written.

USG CORPORATION,

by /s/ Karen L. Leets
-------------------------------------
Name: Karen L. Leets
Title: Vice President and Treasurer

EACH OF THE SUBSIDIARIES
LISTED ON SCHEDULE I HERETO,

By /s/ Karen L. Leets
-------------------------------------
Name: Karen L. Leets
Title: In the capacity listed on
Schedule I corresponding to such
Subsidiary

JPMORGAN CHASE BANK, N.A., AS
ADMINISTRATIVE AGENT,

By /s/ Gary L. Spevack
-------------------------------------
Name: Gary L. Spevack
Title: Vice President

Schedule I to the
Guarantee Agreement

GUARANTORS

COMPANY TITLE OF KAREN L. LEETS WITH RESPECT TO SUCH COMPANY
- ------- ----------------------------------------------------

B-R Pipeline Company Vice President and Treasurer
Gypsum Engineering Company Vice President and Treasurer
L&W Supply Corporation Vice President and Treasurer
Livonia Holdings, Inc. Vice President and Treasurer
Otsego Paper, Inc. Vice President and Treasurer
River City Materials, Inc. Vice President and Treasurer
Stocking Specialists, Inc. Vice President and Assistant Treasurer
United States Gypsum Company Vice President and Treasurer
USG Foreign Investments, Ltd. Vice President and Treasurer
USG Interiors International, Inc. Vice President and Treasurer
USG Interiors, Inc. Vice President and Treasurer
USG International, Ltd. Vice President and Treasurer
USG Latin America, Inc. Vice President and Treasurer
USG Pacific Rim Company, Inc. Vice President and Treasurer
USG Pipeline Company Vice President and Treasurer

Exhibit I to the
Guarantee Agreement

SUPPLEMENT NO. __ dated as of _______, to the Guarantee
Agreement dated as of August 2, 2006 among USG CORPORATION, a
Delaware corporation (the "BORROWER"), each subsidiary of the
Borrower listed on Schedule I thereto (each such subsidiary
individually a "SUBSIDIARY GUARANTOr" and collectively, the
"SUBSIDIARY GUARANTORS"; the Subsidiary Guarantors, and the
Borrower are referred to collectively herein as the "GUARANTORS")
and JPMORGAN CHASE BANK, N.A., a New York banking corporation
("JPMCB"), as Administrative Agent (in such capacity, the
"ADMINISTRATIVE AGENT").

A. Reference is made to the Credit Agreement dated as of August 2,
2006 (as amended, supplemented or otherwise modified from time to time, the
"CREDIT AGREEMENT"), among the Borrower, the lenders from time to time party
thereto, JPMCB, as Administrative Agent and Goldman Sachs Credit Partners L.P.,
as Syndication Agent.

B. Capitalized terms used herein and not otherwise defined herein
shall have the meanings assigned to such terms in the Credit Agreement and the
Guarantee Agreement referred to therein.

C. The Guarantors have entered into the Guarantee Agreement in order
to induce the Lenders to make Loans and the Issuing Bank to issue Letters of
Credit. Section 4.14 of the Guarantee Agreement provides that additional
Subsidiaries of the Borrower may become Guarantors under the Guarantee Agreement
by execution and delivery of an instrument in the form of this Supplement. The
undersigned Subsidiary (the "NEW SUBSIDIARY") is executing this Supplement in
accordance with the requirements of the Credit Agreement to become a Guarantor
under the Guarantee Agreement in order to induce the Lenders to make additional
Loans and the Issuing Bank to issue additional Letters of Credit and as
consideration for Loans previously made and Letters of Credit previously issued.

Accordingly, the Administrative Agent and the New Subsidiary agree as
follows:

SECTION 1. In accordance with Section 4.14 of the Guarantee Agreement,
the New Subsidiary by its signature below becomes a Guarantor under the
Guarantee Agreement with the same force and effect as if originally named
therein as a Guarantor and the New Subsidiary hereby (a) agrees to all the terms
and provisions of the Guarantee Agreement applicable to it as a Guarantor
thereunder and (b) represents and warrants that the representations and
warranties made by it as a Guarantor thereunder are true and correct on and as
of the date hereof. Each reference to a "Guarantor" in the Guarantee Agreement
shall be deemed to include the New Subsidiary. The Guarantee Agreement is hereby
incorporated herein by reference.

SECTION 2. The New Subsidiary represents and warrants to the
Administrative Agent and the other Guaranteed Parties that this Supplement has
been

duly authorized, executed and delivered by it and constitutes its legal,
valid and binding obligation, enforceable against it in accordance with its
terms.

SECTION 3. This Supplement may be executed in counterparts (and by
different parties hereto on different counterparts), each of which shall
constitute an original, but all of which when taken together shall constitute a
single contract. This Supplement shall become effective when the Administrative
Agent shall have received a counterpart of this Supplement that bears the
signature of the New Subsidiary and the Administrative Agent has executed a
counterpart hereof. Delivery of an executed signature page to this Supplement by
facsimile transmission shall be as effective as delivery of a manually signed
counterpart of this Supplement.

SECTION 4. Except as expressly supplemented hereby, the Guarantee
Agreement shall remain in full force and effect.

SECTION 5. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 6. In case any one or more of the provisions contained in this
Supplement should be held invalid, illegal or unenforceable in any respect, the
validity, legality and enforceability of the remaining provisions contained
herein and in the Guarantee Agreement shall not in any way be affected or
impaired thereby (it being understood that the invalidity of a particular
provision in a particular jurisdiction shall not in and of itself affect the
validity of such provision in any other jurisdiction). The parties hereto shall
endeavor in good-faith negotiations to replace the invalid, illegal or
unenforceable provisions with valid provisions the economic effect of which
comes as close as possible to that of the invalid, illegal or unenforceable
provisions.

SECTION 7. All communications and notices hereunder shall be in
writing and given as provided in Section 4.01 of the Guarantee Agreement.

SECTION 8. The New Subsidiary agrees to reimburse the Administrative
Agent for its reasonable out-of-pocket expenses in connection with this
Supplement, including the reasonable fees, other charges and disbursements of
counsel for the Administrative Agent.

IN WITNESS WHEREOF, the New Subsidiary and the Administrative Agent
have duly executed this Supplement to the Guarantee Agreement as of the day and
year first above written.

[NAME OF NEW SUBSIDIARY],

by
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Name:
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Title:
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JPMORGAN CHASE BANK, N.A.,
AS ADMINISTRATIVE AGENT

by
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Name:
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Title:
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