SEC Form 3

FORM 3

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

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1. Name and Address of Reporting Person* Hill Thomas W. (Last) (First) (Middle) C/O SUMMIT MATERIALS, INC. 1550 WYNKOOP STREET, 3RD FLOOR (Street) DENVER CO 80202 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 03/12/2015	3. Issuer Name and Ticker or Trading Symbol Summit Materials, Inc. [ SUM ]
		4. 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	5. If Amendment, Date of Original Filed (Month/Day/Year) 03/12/2015
			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
LP Units of Summit Materials Holdings L.P.	(1)	(1)	Class A Common Stock	1,034,709(2)(3)	(1)	D
LP Units of Summit Materials Holdings L.P.	(1)	(1)	Class A Common Stock	550,550(2)(3)	(1)	I	See Footnote(4)

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 on a one-for-one basis.

2. The initial Form 3 filed on March 12, 2015, incorrectly reflected the effect of an attempted gift of LP Units from the Reporting Person to a family trust prior to the issuer's initial public offering. The attempted gift was ineffectively made and therefore the purported transfer of LP Units was void ab initio. This Amendment is being filed to correct the number of LP Units reported as beneficially owned directly and indirectly by the Reporting Person as of March 12, 2015 after taking into account the voided gift described herein. The total number of LP Units directly and indirectly beneficially owned by the Reporting Person is unchanged, but the allocation between direct/indirect has been updated.

3. These transactions also affect the reported balances on subsequent Forms 4 filed by the Reporting Person through March 2, 2017. The sales reported by the Reporting Person on such Forms 4 correctly reported sales by the trust and did not include the LP Units that were the subject of the ineffective transfer, which have not been sold or otherwise disposed of.

4. Reflects securities held by a trust for the benefit of Mr. Hill's family, for which Mr. Hill's spouse serves as trustee.

	/s/ Anne Lee Benedict, as Attorney-in-Fact	03/02/2017
	** 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).
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