Washington, D.C. 20549


Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB Number: 3235-0104
Estimated average burden
hours per response: 0.5
1. Name and Address of Reporting Person*
Johnson Timothy D

(Last) (First) (Middle)
2001 BRYAN ST., SUITE 1600


(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
3. Issuer Name and Ticker or Trading Symbol
Builders FirstSource, Inc. [ BLDR ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director 10% Owner
X Officer (give title below) Other (specify below)
EVP & General Counsel
5. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Explanation of Responses:
On January 1, 2021, the merger (the "Merger") of Boston Merger Sub I Inc., a subsidiary of the Issuer, with and into BMC Stock Holdings, Inc., pursuant to the Agreement and Plan of Merger, dated as of August 26, 2020, was completed. This report reflects the beneficial ownership of the Reporting Person at the time of completion of the Merger and does not include the securities of the Issuer acquired by the Reporting Person upon the completion of the Merger. The Reporting Person will file a Form 4 reflecting the Reporting Person's acquisition of securities of the Issuer in connection with the completion of the Merger.
No securities are beneficially owned.
/s/ Minator Azemi, by power of attorney 01/05/2021
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

      KNOW ALL PERSONS BY THESE PRESENTS that the undersigned hereby authorizes,
designates, and appoints Jeffrey A. Wier and Minator Azemi as such person's true
and lawful attorneys-in-fact and agents, with full power of substitution and
resubstitution and full power to act, for the undersigned and in the
undersigned's name, place, and stead, to execute, acknowledge, deliver, and file
any and all statements required to be filed with the United States Securities
and Exchange Commission (the "Commission") by the undersigned pursuant to 1)
Section 16 of the Securities Exchange Act of 1934, as amended (the "1934 Act")
or 2) Rule 144 promulgated under the Securities Act of 1933, as amended (the
"1933 Act"), and the rules and regulations thereunder with respect to securities
of Builders FirstSource, Inc., a Delaware corporation, including, without
limitation, statements on Form ID, Form 3, Form 4, Form 5 and Form 144 (and any
amendments thereto) and any successor forms adopted by the Commission, as
required by the 1934 Act or the 1933 Act and the rules and regulations
thereunder, and to take such other actions as such attorneys-in-fact may deem
necessary or appropriate in connection with such statements.

      This power of attorney shall continue in effect until the undersigned no
longer has an obligation to file statements under Section 16 of the 1934 Act or
Rule 144 under the 1933 Act, or until specifically terminated in writing by the
undersigned.  The undersigned acknowledges that the aforesaid persons are not
assuming any of the undersigned's responsibilities to comply with Section 16 of
the 1934 Act or Rule 144 under the 1933 Act.

      IN WITNESS WHEREOF, the undersigned has duly executed this power of
attorney on the 1st day of January, 2021.

                                    By:	/s/ Timothy D. Johnson
	Timothy D. Johnson