IBP: Material agreement · Unregistered securities sale · Company disclosure

Item 1.01 Entry into a Material Definitive Agreement On November 12, 2026 (the “Closing Date”), Installed Building Products, Inc., a Delaware corporation (the “Company”), entered into and consummated the transactions contemplated by an Agreement and Plan of Merger (the “Merger Agreement”) by and among the Company, Platform MSI, Inc., a Delaware corporation (“Merger Sub I”), and IBP Mechanical & Industrial Installation, LLC, a Delaware limited liability company (“Merger Sub II”), each a direct wholly owned subsidiary of the Company, 1981 Holdco, Inc., a Virginia corporation (“Holdco”), Shareholder Representative Services LLC, a Colorado limited liability company, solely in its capacity as representative of the shareholders of Holdco, and Jeff Davoud, an individual, solely for purposes of certain enumerated sections of the Merger Agreement. Holdco conducts its business through its subsidiaries, including Old Dominion Insulation, Inc. and Old Dominion Firestopping, L.L.C. (all such subsidiaries, collectively with Holdco, “Old Dominion Group” or “ODG”). ODG is a leading mechanical and industrial installer of insulation, firestopping and other complementary products, serving customers in high-growth commercial end markets, including healthcare, education, manufacturing, industrial facilities and data centers, and operating under its recognized regional brands. Pursuant to the Merger Agreement, Merger Sub I merged with and into Holdco, with Holdco as the surviving corporation, and promptly thereafter, Holdco merged with and into Merger Sub II, with Merger Sub II surviving as a wholly owned subsidiary of the Company (together, the “Merger,” and the Company’s resulting acquisition of ODG, the “Acquisition”). The parties intend for the Merger to qualify as a “reorganization” wit