X0306 4 2018-03-12 0 0001316835 Builders FirstSource, Inc. BLDR 0001326954 MCALEENAN DONALD F 2001 BRYAN STREET SUITE 1600 DALLAS TX 75201 0 1 0 0 SVP & General Counsel Common Stock, par value $0.01 per share 2018-03-12 4 M 0 194043 3.19 A 442148 D Common Stock, par value $0.01 per share 2018-03-12 4 S 0 194043 21.66 D 248105 D Employee Stock Option (right to buy) 3.19 2018-03-12 4 M 0 194043 0.00 D 2020-02-03 Common Stock 194043 0 D This transaction was executed in multiple trades at prices ranging from $21.50 to $21.73 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. Award issued under the Company's 2007 Incentive Plan, as amended and restated on January 14, 2010. The option was granted on February 3, 2010 and vested in 33.33% increments on each of February 3, 2012-2014. /s/ Jeffrey A. Wier, by power of attorney 2018-03-14