UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant To Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (date of earliest event reported): April 24, 2015 (April 24, 2015)

Builders FirstSource, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware

(State or Other Jurisdiction

of Incorporation)

2001 Bryan Street, Suite 1600, Dallas, Texas 75201

(Address of Principal Executive Offices, Including Zip Code)

(214) 880-3500

(Registrant’s Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On April 27, 2015, Builders FirstSource, Inc. (the “Company”) will be providing a lender presentation, an excerpt of which is being furnished as Exhibit 99.1, to certain lenders in connection with the contemplated debt financing of the Company’s previously announced acquisition of ProBuild Holdings LLC (the “Acquisition”). Completion of the Acquisition remains subject to certain regulatory approvals and other customary conditions. There can be no assurance that the contemplated financing or the Acquisition will be completed.

The information contained in this Item 7.01 and in the accompanying Exhibit 99.1 shall not be deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing. The Company undertakes no duty or obligation to publicly update or revise this information.

The Company’s presentation, in addition to containing results that are determined in accordance with accounting principles generally accepted in the United States of America (“GAAP”), contains certain “non-GAAP financial measures” as that term is defined by the rules and regulations of the Securities and Exchange Commission (“SEC”).

The non-GAAP financial measures used in the presentation should not be considered in isolation of, as a substitute for, or superior to, financial information prepared in accordance with GAAP. The non-GAAP financial measures as defined in the presentation may differ from similarly titled measures presented by other companies. The non-GAAP financial measures, as well as other information in the presentation, should be read in conjunction with the Company’s financial statements filed with the SEC.

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.

Dated: April 24, 2015

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