13G Filing: Stadium Capital Management Files Update on Builders Firstsource, Inc. (BLDR)

EXHIBIT A

AGREEMENT REGARDING JOINT FILING

OF STATEMENT ON SCHEDULE 13D OR 13G

The undersigned agree to file jointly with
the Securities and Exchange Commission (the “SEC”) any and all statements on Schedule 13D or Schedule 13G (and any amendments
or supplements thereto) required under section 13(d) of the Securities Exchange Act of 1934, as amended, in connection with purchases
by the undersigned of the common stock of Builders FirstSource, Inc. For that purpose, the undersigned hereby constitute and appoint
Stadium Capital Management, LLC, a Delaware limited liability company, as their true and lawful agent and attorney-in-fact, with
full power and authority for and on behalf of the undersigned to prepare or cause to be prepared, sign, file with the SEC and furnish
to any other person all certificates, instruments, agreements and documents necessary to comply with section 13(d) and section
16(a) of the Securities Exchange Act of 1934, as amended, in connection with said purchases, and to do and perform every act necessary
and proper to be done incident to the exercise of the foregoing power, as fully as the undersigned might or could do if personally
present.

Dated: February 13, 2014