Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On June 3, 2026, Mark A. Alexander notified the Board of Directors (the “Board”) of Builders FirstSource, Inc. (the “Company”) of his resignation from the Board, effective immediately, due to health reasons. Mr. Alexander’s resignation was not the result of any disagreement with the Company on any matter relating to the Company’s operations, policies, or practices. The Company thanks Mr. Alexander for his wise counsel, valued insights, and meaningful contributions to the Company. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. BUILDERS FIRSTSOURCE, INC. Date: June 5, 2026 By: /s/ Alena Brenner Alena Brenner, Executive Vice President, Chief Legal Officer and Corporate Secretary