Builders FirstSource, Inc.

As permitted by federal securities laws, Builders FirstSource is making this Proxy Statement and 2025 Annual Report on Form 10-K (the “2025 Annual Report”) available to its stockholders primarily via the internet instead of mailing printed copies of these materials to each stockholder. On or about April 2, 2026, we will mail to our stockholders (other than those who previously requested electronic or paper delivery) a Notice Regarding Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access the Proxy Statement and accompanying 2025 Annual Report. These proxy materials will be made available to our stockholders on or about April 2, 2026. The Notice provides instructions regarding how to vote through the internet. The Proxy Statement and 2025 Annual Report are also available on the Investors section of our website, under the heading entitled "Financials," at www.bldr.com.

If you received a Notice by mail, you will not receive a printed copy of the proxy materials by mail unless you request printed materials. If you wish to receive printed proxy materials, you should follow the instructions for requesting such materials contained on the Notice.

If you receive more than one Notice, it means your shares are registered differently and are held in more than one account. To ensure all shares are voted, please either vote each account over the internet or by telephone or sign and return by mail all proxy cards.

GENERAL INFORMATION ABOUT PROXIES AND VOTING