Installed Building Products, Inc.

1. PJAM IBP Holdings, Inc. ("PJAM") sold 400,000 shares of common stock of Installed Building Products, Inc. through a block trade pursuant to Rule 144 under the Securities Act of 1933, as amended.

2. These securities are held directly by PJAM. The Reporting Persons disclaim beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein. IBP Holding Company is the sole shareholder of PJAM.

3. These securities are held directly by Installed Building Systems, Inc. ("IBS"). Mr. Edwards disclaims beneficial ownership in the reported securities except to the extent of his pecuniary interest therein. IBS and Mr. Edwards remain the beneficial owners of all Pledged Shares, as defined in Footnote 5, reported in Table II to the extent of his or its pecuniary interest therein. Mr. Edwards is the sole beneficial owner of the shares reported in Table I as directly owned.

4. The securities are held by a trust for the benefit of one of Mr. Edwards' children. Mr. Edwards disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein.

5. As previously reported, IBS entered into two prepaid variable forward sale contracts on each of September 2023, November 2023 and May 2024 with an unaffiliated third party buyer. In each of the September and November transactions, IBS pledged 450,000 shares, or 225,000 shares per contract and 900,000 shares in the aggregate, and in the May transaction, IBS pledged 250,000 shares, or 125,000 shares per contract (collectively, the "Pledged Shares") of Installed Building Products, Inc. common stock ("Common Stock"). The Pledged Shares secure its obligations under the contracts, and IBS retained dividend and voting rights in the Pledged Shares during the term of the pledge. The contracts obligate IBS to deliver to the buyer, on the applicable settlement date for each component referred to in footnote 10 below, up to one hundred percent (100%) of the number of Pledged Shares for such component or, at IBS' option, an equivalent amount of cash.

6. On August 12, 2025, IBS and the buyer entered into an amendment to the September 2023 forward sale contract and the May 2024 forward sale contract. On March 3, 2026, IBS and the buyer entered into a second amendment to the September 2023 forward sale contract (the "September Amendment Agreement") and the May 2024 forward sale contract (the "May Amendment Agreement" and collectively the "2026 Amendment Agreements"). The reference price for the 2026 Amendment Agreements was $314.06. The September Amendment Agreement amends certain terms of one of the forward sale contracts entered into in September 2023, covering 225,000 shares of Common Stock, including (i) extending the range of settlement dates for the components from March 9, 2026 through March 13, 2026 to the new settlement dates from May 24, 2027 through June 4, 2027,

7. (Continued from footnote 6) (ii) amending the Floor Price (as defined below) and the Cap Price (as defined below), and (iii) increasing the number of components from 5 to 9, with appropriate adjustment for the number of shares to be delivered on the respective settlement date for each component. The May Amendment Agreement amends certain terms of one of the forward sale contracts entered into in May 2024, covering 125,000 shares of Common Stock, including (i) extending the range of settlement dates for the components from March 9, 2026 through March 13, 2026 to the new settlement dates from May 24, 2027 through June 4, 2027, (ii) amending the Floor Price (as defined below) and the Cap Price (as defined below), and (iii) increasing the number of components from 5 to 9, with appropriate adjustments for the number of shares to be delivered on the respective settlement date for each component.

8. (Continued from footnote 7) The number of shares of Common Stock to be delivered to the buyer on the settlement date (or on which to base the amount of cash to be delivered to the buyer on such settlement date) under each Amendment Agreement is to be determined as follows: (a) if the VWAP of the Common Stock on the designated valuation date for the applicable component (each, a "Settlement Price") is less than or equal to $314.06 (the "Floor Price"), IBS will deliver to the buyer all of the Pledged Shares for the applicable component;

9. (Continued from footnote 8) (b) if such Settlement Price is greater than the Floor Price but less than or equal to $376.872 (the "Cap Price"), IBS will deliver to the buyer the number of shares equal to 100% of the Pledged Shares for the applicable component multiplied by a fraction, the numerator of which is the Floor Price and the denominator of which is such Settlement Price; and (c) if such Settlement Price is greater than the Cap Price, IBS will deliver to the buyer the number of shares equal to 100% of the Pledged Shares for the applicable component multiplied by a fraction, the numerator of which is the Floor Price plus the excess of such Settlement Price over the Cap Price, and the denominator of which is such Settlement Price.

10. Each component is exercisable on the same date as it expires, and the expiration dates for the components occur from May 24, 2027 through June 4, 2027 under the 2026 Amendment Agreements.

11. These securities are held directly by IBS. Mr. Edwards disclaims beneficial ownership in the reported securities except to the extent of his pecuniary interest therein.