Sec Form 4 Filing - GARDNER TED A @ Summit Materials, Inc. - 2018-02-27

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person GARDNER TED A 2. Issuer Name and Ticker or Trading Symbol Summit Materials, Inc. [ SUM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SUMMIT MATERIALS, INC., 1550 WYNKOOP STREET, 3RD FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 02/27/2018 (Street) DENVER, CO80202 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Class A Common Stock 02/27/2018 C 40,000 A 40,000 I See Footnote ( 2 ) Class A Common Stock 02/28/2018 M 4,098 A 10,601 ( 4 ) D Class A Common Stock 03/01/2018 S 30,000 D $ 32.01 ( 5 ) 10,000 I See Footnote ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares LP Units of Summit Materials Holdings L.P. ( 1 ) 02/27/2018 C 40,000 ( 1 ) ( 1 ) Class A Common Stock 40,000 $ 0 162,752 I See Footnote ( 2 ) Restricted Stock Units ( 6 ) 02/28/2018 M 4,098 ( 7 ) ( 7 ) Class A Common Stock 4,098 $ 0 0 D Restricted Stock Units ( 6 ) 02/28/2018 A 3,994 ( 8 ) ( 8 ) Class A Common Stock 3,994 $ 0 3,994 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GARDNER TED A C/O SUMMIT MATERIALS, INC. 1550 WYNKOOP STREET, 3RD FLOOR DENVER, CO80202 X Signatures /s/Anne Lee Benedict, as Attorney-in-Fact 03/01/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. ("LP Units") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock ("Class A Common Stock") on a one-for-one basis. ( 2 )Reflects securities held by a limited liability company controlled by Mr. Gardner. ( 3 )Reflects restricted stock units that upon vesting converted into shares of Class A Common Stock on a one-for-one basis. ( 4 )Total holdings include shares of Class A Common Stock received pursuant to a stock dividend paid on December 22, 2017. ( 5 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.82 to $32.26, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. ( 6 )Each restricted stock unit represents a contingent right to receive one share of Issuer Class A Common Stock. The restricted stock units will be settled in either Class A Common Stock or cash (or a combination thereof) at the discretion of the Issuer's compensation committee. ( 7 )On February 28, 2017, the Reporting Person was granted 4,098 restricted stock units that vested on February 28, 2018. ( 8 )These restricted stock units vest on February 28, 2019.

Remarks: The Reporting Person disclaims beneficial ownership of the securities reported herein as indirectly beneficially owned, except to the extent of his pecuniary interest therein.

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 4(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.