X0306 4 2019-08-09 0 0001316835 Builders FirstSource, Inc. BLDR 0001689573 Jackson Peter M. 2001 BRYAN ST., SUITE 1600 DALLAS TX 75201 0 1 0 0 SVP & CFO Common Stock, par value $0.01 per share 2019-08-09 4 S 0 4328 20.20 D 53096 D This transaction was executed in multiple trades at prices ranging from $20.19 to $20.23 per share. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide full information regarding the number of shares and prices at which the transactions were effected upon request by the SEC staff, the issuer, or a security holder of the issuer. /s/ Jeffrey A. Wier, by power of attorney 2019-08-12