BLDR: Leadership change · Company disclosure

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On May 18, 2026, Builders FirstSource, Inc. (the “Company”) announced that, as part of its planned leadership transition, its Board of Directors (the “Board”) appointed Mike Hiller, Chief Talent Officer of the Company, as Chief Operating Officer-Designate effective May 18, 2026. Mr. Hiller will succeed Steve Herron, as Chief Operating Officer effective December 31, 2026. Mr. Herron has served as Chief Operating Officer of the Company since March 2023 and is retiring after over 15 years of dedicated service to the Company. Mr. Hiller, 52, was appointed as Chief Talent Officer of the Company in November 2024. Prior to this appointment, he served as President – Central Division, since January 2021. Prior to joining the Company, Mr. Hiller served in various roles at BMC Stock Holdings, Inc., including Vice President – Intermountain Region from January 2017 to December 2020, Area Manager – Colorado from January 2015 to December 2016, and Area Manager – Utah from October 2011 to December 2014. Mr. Hiller has over 20 years of experience in the building products industry. He holds a Master of Business Administration and graduate certificate in finance from Westminster University. Additionally, the Board appointed Coley O’Brien to succeed Mr. Hiller as Chief Human Resources Officer, effective May 18, 2026. Mr. O’Brien joins the Company from The Wendy’s Company, where he was Chief People Officer since March 2018. The information required by Item 5.02(c)(3) of Form 8-K for Mr. Hiller has not been determined as of the date hereof. The Company will provide such information, if applicable, in an amendment to this Form 8-K within