Ownership Submission
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 OF SECURITIES

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
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Hill Thomas W.
   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
__X__ Officer (give title below) _____ Other (specify below)
President and CEO
(Last)
(First)
(Middle)
C/O SUMMIT MATERIALS, INC., 1550 WYNKOOP STREET, 3RD FLOOR		 3. Date of Earliest Transaction (Month/Day/Year)
08/04/2017
(Street)

DENVER, CO 80202		 4. If Amendment, Date 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
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 08/04/2017   C   50,000 A (1) 70,610 D  
Class A Common Stock 08/04/2017   C   25,000 A (1) 37,860 I See Footnote (2)
Class A Common Stock 08/04/2017   M   209,319 A $ 18 279,929 D  
Class A Common Stock 08/04/2017   S   209,319 D $ 29.28 (3) 70,610 D  
Class A Common Stock 08/07/2017   M   70,271 A $ 18 140,881 D  
Class A Common Stock 08/07/2017   M   70,410 A $ 18 211,291 D  
Class A Common Stock 08/07/2017   S   40,681 D $ 29.42 (4) 170,610 D  

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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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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
(Month/Day/Year)		 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) 08/04/2017   C     50,000   (1)   (1) Class A Common Stock 50,000 (1) 692,456 D  
LP Units of Summit Materials Holdings L.P. (1) 08/04/2017   C     25,000   (1)   (1) Class A Common Stock 25,000 (1) 26,969 I See Footnote (2)
Options (right to buy) $ 18 08/04/2017   M     209,319   (5) 03/11/2025 Class A Common Stock 209,319 $ 0 349,862 D  
Options (right to buy) $ 18 08/07/2017   M     70,271   (5) 03/11/2025 Class A Common Stock 70,271 $ 0 279,591 D  
Options (right to buy) $ 18 08/07/2017   M     70,410   (6) 03/11/2025 Class A Common Stock 70,410 $ 0 656,523 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Hill Thomas W.
C/O SUMMIT MATERIALS, INC.
1550 WYNKOOP STREET, 3RD FLOOR
DENVER, CO 80202		   X     President and CEO  

Signatures

 /s/ Anne Lee Benedict, as Attorney-in-Fact   08/08/2017
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(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 on a one-for-one basis.
(2) Reflects securities held by a trust for the benefit of Mr. Hill's family, for which Mr. Hill's spouse serves as trustee.
(3) The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.04 to $29.52, 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.
(4) The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.22 to $29.64, 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.
(5) Reflects the grant of 559,181 options that vest in four equal annual installments beginning on March 11, 2016.
(6) Reflects the grant of 726,933 options that vest in four equal annual installments beginning on March 11, 2016.
 
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.

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