Builders FirstSource, Inc.

Annual Meeting of Stockholders

May 14, 2026

This Proxy Statement is being furnished by Builders FirstSource, Inc. (the “Corporation,” the “Company,” or “Builders FirstSource”) in connection with a solicitation of proxies by its Board of Directors (the “Board of Directors” or the “Board”) to be voted at the annual meeting of the Corporation’s stockholders to be held on May 14, 2026 (the “annual meeting” or “meeting”). Whether or not you personally attend, it is important that your shares be represented and voted at the annual meeting. Most stockholders have a choice of voting over the internet, by using a toll-free telephone number, or, for stockholders who elect to receive their proxy materials by mail, by completing a proxy card and mailing it in the postage-paid envelope provided. Check the Notice Regarding the Availability of Proxy Materials, your proxy card, or the information forwarded by your bank, broker, or other stockholder of record, as applicable, to determine which voting options are available to you. The internet voting and telephone voting facilities for stockholders of record will be available until 8:00 a.m. Central Time on May 14, 2026. The Notice Regarding the Availability of Proxy Materials will first be mailed on or about April 2, 2026.