X0609 4 2026-10-18 0001316835 Builders FirstSource, Inc. BLDR 0001837949 Hiller Michael false C/O BUILDERS FIRSTSOURCE, INC. 6031 CONNECTION DR., STE. 400 IRVING TX 75039 false true false false COO-Designate false Common Stock, par value $0.01 per share 2026-10-18 4 A false 12808 0.00 A 64950 D Reflects the acquisition of restricted stock units pursuant to the Corporation's 2026 Incentive Plan. The restricted stock units vest in 33.3% increments on each of October 18, 2027-2029 and entitle the reporting person to one share of common stock for each restricted stock unit that vests. /s/ Alena Brenner, by power of attorney 2026-10-20