1 EXHIBIT 23.1 The Board of Directors Modtech Holdings, Inc.: We consent to incorporation by reference in the registration statements (No. 333-79023 and No. 333-81169) on Form S-8 of Modtech Holdings, Inc. of our report dated March 10, 2000, relating to the consolidated balance sheets of Modtech Holdings, Inc. and subsidiaries as of December 31, 1998, and 1999, and the related consolidated statements of income, retained earnings, and cash flows for each of the years in the three-year period ended December 31, 1999, and all related schedules, which report appears in the December 31, 1999, annual report on Form 10-K of Modtech Holdings, Inc. /s/ KPMG LLP Orange County, California March 30, 2000