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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

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SCHEDULE 14A
Proxy Statement Pursuant to Section 14
(a) of the
Securities Exchange Act of 1934
(Amendment No.     )

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NOTICE OF 2018 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on Thursday, May 17, 2018

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              The 2018 Annual Meeting of Stockholders (the "Annual Meeting") of Summit Materials, Inc. ("Summit Materials" or the "Company") will be held at 8:00 a.m., Eastern Time, on Thursday, May 17, 2018, at the offices of the Company's subsidiary, Hinkle Contracting Company, LLC, located at 101 Helm St., Suite 110, Lexington, Kentucky 40505 for the following purposes:

       1.  To elect the two nominees for director named in the attached Proxy Statement to serve until the 2021 Annual Meeting of Stockholders and until their respective successors are elected and qualified;

       2.  To ratify the appointment of KPMG LLP ("KPMG") as our independent registered public accounting firm for our fiscal year ending December 29, 2018;

       3.  To approve, on a nonbinding advisory basis, the compensation of our named executive officers ("NEOs"), as disclosed in the Proxy Statement; and

       4.  To transact such other business as may properly come before the Annual Meeting or any adjournment or postponement thereof.

              Our Board of Directors recommends you vote (i) "FOR" the election of each of the nominees to the Board; (ii) "FOR" the ratification of the appointment of KPMG as our independent registered public accounting firm; and (iii) "FOR" the approval, on a nonbinding advisory basis, of the compensation of our NEOs, as disclosed in the Proxy Statement.

              The Board of Directors has fixed March 19, 2018 as the record date for determining stockholders entitled to receive notice of, and to vote at, the Annual Meeting or any adjournment or postponement thereof. Only stockholders of record at the close of business on that date will be entitled to notice of, and to vote at, the Annual Meeting.

Denver, Colorado
March 30, 2018

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PROXY SUMMARY

The following description is a summary that highlights certain information in the Proxy Statement. You should read the entire Proxy Statement carefully before voting. Your vote is important. Whether or not you plan to attend the Annual Meeting, we encourage you to vote your shares promptly.

DATE:  May 17, 2018
TIME:  8:00 a.m., Eastern Time
LOCATION:  The offices of the Company's subsidiary, Hinkle Contracting Company, LLC, located at 101 Helm St., Suite 110, Lexington, Kentucky 40505

Highlights of our 2017 business achievements included the following:

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Full-year organic sales volumes of aggregates increased 3.4%.

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Full-year organic sales volumes of cement increased 5.8%.

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Full-year net income increased 331.2% to $121.83 million.

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Full-year operating income increased 42.8% to $220.9 million.

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Full-year adjusted EBITDA* increased 17.4% to $435.8 million.

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See "Reconciliation of Non-GAAP Measure to GAAP" on Annex A.

For a more detailed discussion on our financial performance, see our combined Annual Report to Stockholders and Annual Report on Form 10-K for the year ended December 30, 2017 (the "2017 Annual Report"), available at www.proxyvote.com.

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You will find important information about the qualifications of each of our director nominees beginning on page 9. Our Board of Directors ("Board") recommends that you vote "FOR" each of the following director nominees.

We are seeking ratification of the appointment of KPMG to serve as our independent registered public accounting firm for 2018 as set forth in Item 2 on page 19. Our Board recommends that you vote "FOR" the ratification.

Our stockholders have the opportunity to cast a nonbinding advisory vote on the compensation of our NEOs, as set forth in Item 3 on page 25. Last year, stockholders representing approximately 96% of the votes cast approved our executive compensation program for our NEOs. In evaluating this "say on pay" proposal, we recommend you review our Compensation Discussion and Analysis beginning on page 28, which explains how and why our Compensation Committee arrived at the compensation actions and decisions for 2017. Our Board recommends that you vote "FOR" the approval, on a nonbinding advisory basis, of the compensation of our NEOs.

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SUMMIT MATERIALS, INC.

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PROXY STATEMENT

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ANNUAL MEETING OF STOCKHOLDERS

To Be Held on Thursday, May 17, 2018

GENERAL INFORMATION

              The enclosed proxy is solicited by the Board of Directors (the "Board") of Summit Materials, Inc. ("Summit Materials" or the "Company") for use at the Annual Meeting of Stockholders (the "Annual Meeting") to be held at 8:00 a.m., Eastern Time, on Thursday, May 17, 2018, at the offices of the Company's subsidiary, Hinkle Contracting Company, LLC, located at 101 Helm St., Suite 110, Lexington, Kentucky 40505, and at any adjournment or postponement thereof. Our principal executive offices are located at 1550 Wynkoop Street, 3rd Floor, Denver, Colorado 80202. This Proxy Statement is first being made available to our stockholders on or about March 30, 2018.

              Only holders of record of our Class A Common Stock and Class B Common Stock (each such designation having par value $0.01 per share) at the close of business on March 19, 2018, the record date, will be entitled to notice of, and to vote at, the Annual Meeting. On that date, we had 111,228,077 shares of Class A Common Stock outstanding and entitled to vote and 97 shares of Class B Common Stock outstanding and entitled to vote. Holders of shares of our Class A Common Stock and Class B Common Stock vote together as a single class on all matters on which stockholders are entitled to vote generally (except as may be required by law).

              Each share of Class A Common Stock is entitled to one vote for each director nominee and one vote for each other item to be voted on at the Annual Meeting. All of the shares of our outstanding Class B Common Stock are currently held by our pre-initial public offering ("IPO") investors, including certain members of management or their family trusts that directly hold limited partnership interests (the "LP Units"). A holder of Class B Common Stock is entitled, without regard to the number of shares of Class B Common Stock held by such holder, to a number of votes that is equal to the aggregate number of LP Units held by such holder. As of the record date, the total number of LP Units to which the voting power of the Class B Common Stock relates was 3,332,266.

              A majority of the voting power of Class A Common Stock and Class B Common Stock entitled to vote, present in person or represented by proxy, constitutes a quorum for the transaction of business at the Annual Meeting. Abstentions and broker non-votes will be included in determining the presence of a quorum at the Annual Meeting.

              We are furnishing proxy materials to some of our stockholders via the Internet by mailing a Notice of Internet Availability of Proxy Materials, instead of mailing printed copies of those materials. The Notice of Internet Availability of Proxy Materials directs stockholders to a website where they can access our proxy materials, including this Proxy Statement and our Annual Report on Form 10-K for the year ended

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December 30, 2017 (the "2017 Annual Report"), and view instructions on how to vote via the Internet or by telephone. If you received a Notice of Internet Availability of Proxy Materials and would prefer to receive a paper copy of our proxy materials, please follow the instructions included in the Notice of Internet Availability of Proxy Materials. If you elect to receive our future proxy materials electronically, you will receive access to those materials via e-mail unless and until you elect otherwise.

              Shares that are properly voted via the Internet or by telephone or for which proxy cards are properly executed and returned will be voted at the Annual Meeting in accordance with the directions given or, in the absence of directions, will be voted in accordance with the Board's recommendations as follows: "FOR" the election of each of the nominees to the Board named herein; "FOR" the ratification of the appointment of our independent registered public accounting firm; and "FOR" the approval, on a nonbinding advisory basis, of the compensation of our named executive officers ("NEOs") as disclosed in this Proxy Statement. It is not expected that any additional matters will be brought before the Annual Meeting, but if other matters are properly presented, the persons named as proxies in the proxy card or their substitutes will vote in their discretion on such matters.

              The manner in which your shares may be voted depends on how your shares are held. If you own shares of record, meaning that your shares are represented by certificates or book entries in your name so that you appear as a stockholder on the records of Broadridge Financial Solutions, Inc. ("Broadridge"), our stock transfer agent, you may vote by proxy, meaning you authorize individuals named in the proxy card to vote your shares. You may provide this authorization by voting via the Internet, by telephone or (if you have received paper copies of our proxy materials) by returning a proxy card. In these circumstances, if you do not vote by proxy or in person at the Annual Meeting, your shares will not be voted. If you own shares in street name, meaning that your shares are held by a bank, brokerage firm, or other nominee, you may instruct that institution on how to vote your shares. You may provide these instructions by voting via the Internet, by telephone, or (if you have received paper copies of proxy materials through your bank, brokerage firm, or other nominee) by returning a voting instruction form received from that institution.

              With respect to the election of directors (Item 1), a nominee for director shall be elected to the Board by a plurality of the votes cast in respect of the shares of common stock present in person or represented by proxy at the Annual Meeting and entitled to vote on the election of directors. A plurality vote requirement means that the director nominees with the greatest number of votes cast "FOR," even if less than a majority, will be elected. You may vote "FOR" or "WITHHOLD" with respect to each nominee. A withhold vote in the election of directors will have the same effect as an abstention. Neither a withhold vote nor a broker non-vote will affect the outcome of the election of directors. Broker non-votes occur when a person holding shares in street name, such as through a brokerage firm, does not provide instructions as to how to vote those shares and the broker lacks the authority to vote uninstructed shares at its discretion. Under current New York Stock Exchange ("NYSE") interpretations that govern broker non-votes, Items 1 and 3 are considered non-discretionary matters, and a broker will lack the authority to vote uninstructed shares at its discretion on such proposals. Item 2 is considered a discretionary matter, and a broker will be permitted to exercise its discretion to vote uninstructed shares on the proposal. This means that, if you do not provide voting instructions on Item 2, your broker may nevertheless vote your shares on your behalf with respect to the ratification of the appointment of KPMG as our independent registered public accounting firm for the fiscal year ending December 29, 2018, but cannot vote your shares on any other matters being considered at the Annual Meeting.

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              For all matters proposed for a vote at the Annual Meeting other than the election of directors (Item 1), the affirmative vote of a majority of the voting power of common stock present in person or represented by proxy and entitled to vote on the matter is required to approve the matter. With respect to the ratification of the appointment of KPMG as our independent registered public accounting firm for the fiscal year ending December 29, 2018 (Item 2) and the nonbinding advisory vote on the compensation of our NEOs (Item 3), you may vote "FOR," "AGAINST," or "ABSTAIN." For these matters, abstentions are not counted as affirmative votes on a matter but are counted as present at the Annual Meeting and entitled to vote and will have the effect of a vote "against" the matter, and broker non-votes, if any, will have no effect on the outcome of these matters.

              Voting via the Internet or by telephone helps save money by reducing postage and proxy tabulation costs.

              VOTE BY MAIL. If you have received paper copies of our proxy materials, you have the option to vote by mail by marking, dating and signing your proxy card or voting instruction form and returning it in the postage-paid envelope.

              We encourage you to register to receive all future stockholder communications electronically, instead of in print. This means that, after you register, access to the annual report, proxy statement, and other correspondence will be delivered to you via e-mail.

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              If you own common stock of record, you may attend the Annual Meeting and vote in person, regardless of whether you have previously voted by proxy card, via the Internet or by telephone. If you own common stock in street name, you may attend the Annual Meeting, but in order to vote your shares at the Annual Meeting you must obtain a "legal proxy" from the bank, brokerage firm, or other nominee that holds your shares. You should contact your bank or brokerage account representative to learn how to obtain a legal proxy. We encourage you to vote your shares in advance of the Annual Meeting by one of the methods described above, even if you plan on attending the Annual Meeting. If you have already voted prior to the Annual Meeting, you may nevertheless change or revoke your vote at the Annual Meeting as described below. Only stockholders as of the record date (March 19, 2018) are entitled to attend the Annual Meeting in person. If you own common stock of record, your name will be on a list and you will be able to gain entry with a government-issued photo identification, such as a driver's license, state-issued identification card, or passport. If you own common stock in street name, in order to gain entry you must present a government-issued photo identification and proof of beneficial stock ownership as of the record date, such as your Notice of Internet Availability of Proxy Materials, a copy of your proxy card or voting instruction form if you received one, or an account or brokerage statement or other similar evidence showing stock ownership as of the record date. If you are a representative of an entity that owns common stock of the Company, you must present a government-issued photo identification, evidence that you are the entity's authorized representative or proxyholder and, if the entity is a street name owner, proof of the entity's beneficial stock ownership as of the record date.

              If you are not a stockholder, you will be entitled to admission only if you have a valid legal proxy from a record holder and a government-issued photo identification. Each stockholder may appoint only one proxyholder or representative to attend on his or her behalf.

              You can find directions to the Annual Meeting at investors.summit-materials.com/FinancialDocs. Cameras, recording devices and other electronic devices are prohibited at the Annual Meeting.

              If you own common stock of record, you may revoke your proxy or change your voting instructions at any time before your shares are voted at the Annual Meeting by delivering to the Secretary of the Company a written notice of revocation or a duly executed proxy (via the Internet or telephone or by returning a proxy card) bearing a later date or by attending the Annual Meeting and voting in person. A stockholder owning common stock in street name may revoke or change voting instructions by contacting the bank, brokerage firm or other nominee holding the shares or by obtaining a legal proxy from such institution and voting in person at the Annual Meeting.

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Biographical and Related Information of Director Nominees and Continuing Directors

              The principal occupations and certain other information about our director nominees and our continuing directors (including the skills and qualifications that led to the conclusion that they should serve as directors) are set forth below. The age shown below for each director is as of May 17, 2018, which is the date of the Annual Meeting.

              The Board has nominated two directors to be elected at the Annual Meeting to serve for three-year terms ending with the 2021 Annual Meeting of Stockholders and until a successor is duly elected and qualified, or until the earlier of the director's death, resignation or removal. Each nominee is currently a director of the Company and has agreed to serve if elected.

              Howard L. Lance, 62, began to serve on the Board in October 2012 and was formally elected as a director and Chairman in February 2013. He has served as President and Chief Executive Officer of Maxar

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Technologies Ltd. ("Maxar"), formerly known as MacDonald, Dettwiler and Associates Ltd., a global communications and information company, since May 2016. Mr. Lance also sits on Maxar's board of directors. Prior to joining Maxar, Mr. Lance was an Executive Advisor to The Blackstone Group L.P. ("Blackstone") and as part of his duties as such, he served on the boards of certain Blackstone portfolio companies. He is also a director of Change Healthcare, Inc. He was Chairman of the Board of Directors, President and Chief Executive Officer of Harris Corporation from 2003 to 2011. Before joining Harris Corporation, Mr. Lance was president of NCR Corporation and Chief Operating Officer of its Retail and Financial Group. Previously, he spent 17 years with Emerson Electric Co., where he held senior management positions including Executive Vice President of its Electronics and Telecommunications segment, Chief Executive Officer and director of its Astec electronics subsidiary in Hong Kong, Group Vice President of its Climate Technologies segment and President of its Copeland Refrigeration division. Mr. Lance has a Bachelor of Science degree in Industrial Engineering from Bradley University and a Master of Science degree in Management from the Krannert School of Management at Purdue University.

              In nominating Mr. Lance for reelection as a director, the Board considered Mr. Lance's significant management and operational experience from his service in various senior management roles, including as President and Chief Executive Officer of Maxar and of Harris Corporation and as President and Chief Operating Officer of NCR Corporation.

              Anne K. Wade, 46, was appointed by the Board as a director in January 2016, at which time she was also appointed to the Audit Committee. From 1995 to 2012, Ms. Wade held positions of increasing responsibility, most recently as Senior Vice President and Director, at Capital International, a part of the Capital Group Companies, the Los Angeles based investment management firm. Ms. Wade is currently a partner at Leaders' Quest, an organization focused on culture, values, and driving social and financial impact in major corporations. In that capacity she was the co-Director of the BankingFutures initiative in the United Kingdom. Ms. Wade also currently serves on the Boards of Directors of the John Laing Group plc, where she chairs the Remuneration Committee, Big Society Capital Ltd in London, and the Heron Foundation in New York City. She previously served on the Board of Directors of Holcim Ltd from 2013 to 2015, and was a member of its Governance and Strategy Committee. Ms. Wade has a Bachelor of Arts degree, Magna Cum Laude, from Harvard University and a Master of Science from the London School of Economics.

              In nominating Ms. Wade for reelection as a director, the Board considered Ms. Wade's significant financial and investing experience, primarily in infrastructure sectors including the global building materials and construction industries, including as Senior Vice President and Director of Capital International.

              Ted A. Gardner, 60, was elected as a director in August 2009. He is a Managing Partner of Silverhawk Capital Partners (together with its affiliates, "Silverhawk"). Prior to co-founding Silverhawk in 2005, Mr. Gardner was a Managing Partner of Wachovia Capital Partners (formerly, First Union Capital Partners) from 1989 until 2002. He was a director and Chairman of the Compensation Committee of Kinder Morgan, Inc. from 1999 to 2007, a director and the Chairman of the Audit Committee of Encore Acquisition Company from 2001 to 2010, a director of Kinder Morgan Energy Partners from 2011 to 2014 and a director and Chairman of the Audit Committee of Athlon Energy, Inc. from 2013 to 2014. He is currently a director of Kinder Morgan, Inc., Incline Niobrara Partners, LP and Spartan Energy Partners. Mr. Gardner received a Bachelor of Arts degree in Economics from Duke University and a Juris Doctor and Masters of Business Administration from the University of Virginia.

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              Mr. Gardner brings to the Board extensive business and leadership experience, including as a Managing Partner of Silverhawk and Managing Partner of Wachovia Capital Partners (formerly, First Union Capital Partners). In addition, Mr. Gardner has over 30 years of private equity investing experience.

              John R. Murphy, 67, was elected as a director and Chairman of the Audit Committee in February 2012. Since March 2015, he also has served as a member of the Nominating and Corporate Governance Committee. Mr. Murphy served as Summit Materials' Interim Chief Financial Officer from January 2013 to May 2013 and from July 2013 to October 2013. He was Senior Vice President and Chief Financial Officer of Smurfit-Stone Container Corporation from 2009 to 2010 and served in various senior management roles from 1998 to 2008, including Chief Financial Officer and President and Chief Operating Officer and as President and Chief Executive Officer of Accuride Corporation. Accuride Corporation filed for Chapter 11 bankruptcy protection in October 2009 and emerged in 2010. Since 2003, Mr. Murphy has served on the Board, the Governance Committee and as Chairman of the Audit Committee of O'Reilly Automotive, Inc. He has also served as a director and Audit Committee Chairman of DJO Global Inc. since January 2012. Mr. Murphy was elected as a director and Audit Committee member of Graham Packaging in February 2011. Graham Packaging was subsequently sold in September 2011. Mr. Murphy has a Bachelor of Science degree in Accounting from Pennsylvania State University and a Master of Business Administration degree from the University of Colorado and is a Certified Public Accountant.

              Mr. Murphy brings to the Board extensive financial knowledge, including from his service as Chief Financial Officer of Smurfit-Stone Container Corporation and Accuride Corporation.

              Steven H. Wunning, 67, was appointed by the Board as a director in August 2016, at which time he was also appointed to the Compensation Committee. He served as Group President and Executive Office Member for Caterpillar Inc. ("Caterpillar") from January 2004 until his retirement in February 2015. Mr. Wunning joined Caterpillar in 1973 and held a variety of positions of increasing responsibility with Caterpillar, including Vice President, Logistics Division from January 2000 to January 2004 and Vice President, Logistics & Product Services Division from November 1998 to January 2000. Mr. Wunning is also a director of The Sherwin Williams Company, Kennametal Inc., Black & Veatch Holding Company and Neovia Logistics Services, LLC. Mr. Wunning serves on the Board of Trustees of Missouri University of Science and Technology. He obtained his Bachelor of Sciences degree in Metallurgical Engineering from Missouri University of Science and Technology and an executive Masters of Business Administration from the University of Illinois.

              Mr. Wunning brings to the Board expansive operating and board experience across the industrial and building products industries, including his more than 40 years at Caterpillar.

              Thomas W. Hill, 62, is the founder of Summit Materials and has been President and Chief Executive Officer since its inception. He has been a member of the Board of Directors since August 2009. From 2006 to 2008, he was the Chief Executive Officer of Oldcastle, Inc. ("Oldcastle"), the North American arm of CRH plc, one of the world's leading construction materials companies. Mr. Hill served on the CRH plc Board of Directors from 2002 to 2008 and, from 1992 to 2006, ran the Materials division of Oldcastle. Mr. Hill served as Chairman of the American Road and Transportation Builders Association ("ARTBA") from 2002 to 2004, during congressional consideration of the multi-year transportation bill "SAFETEA-LU." Mr. Hill has been Treasurer of both the National Asphalt Pavement Association and the National Stone Association, and he remains active with ARTBA's Executive Committee. Mr. Hill received a Bachelor of Arts in Economics and History from Duke University and a Masters of Business Administration from Trinity College in Dublin, Ireland.

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              Mr. Hill brings to the Board extensive knowledge of our industry and significant experience in leading companies, as well as his ongoing contributions as the Company's CEO.

              Neil P. Simpkins, 52, was elected as a director in August 2009. He is a Senior Managing Director of the Corporate Private Equity Group at Blackstone. Since joining Blackstone in 1998, Mr. Simpkins has led the acquisitions of TRW Automotive, Vanguard Health Systems, Team Health, LLC, Apria Healthcare Group, Summit Materials, Change Healthcare, Inc. and Gates Corporation. Before joining Blackstone, Mr. Simpkins was a Principal at Bain Capital. While at Bain Capital, Mr. Simpkins was involved in the execution of investments in the consumer products, industrial, healthcare and information industries. Prior to joining Bain Capital, Mr. Simpkins was a consultant at Bain & Company in the Asia Pacific region and in London. He currently serves as a Director of Apria Healthcare Group, Gates Corporation, Change Healthcare, Inc. and Team Health Inc. Mr. Simpkins graduated with honors from Oxford University and received a Masters of Business Administration from Harvard Business School.

              Mr. Simpkins brings to the Board significant financial and business experience, including as a Senior Managing Director in the Private Equity Group at Blackstone and Principal at Bain Capital.

              Joseph S. Cantie, 54, was appointed by the Board as a director in May 2016, at which time he was also appointed to the Audit Committee. He is the former Executive Vice President and Chief Financial Officer of ZF TRW, a division of ZF Friedrichshafen AG ("ZF"), a global automotive supplier, a position he held from May 2015 until January 2016. He served in similar roles at TRW Automotive Holdings Corp., which was acquired by ZF Industries in May 2015, since 2003. Prior to that time, Mr. Cantie held other executive positions at TRW, which he joined in 1999. From 1996 to 1999, Mr. Cantie served in several executive positions with LucasVarity Plc, including serving as Vice President and Controller. Prior to joining LucasVarity, Mr. Cantie spent 10 years with KPMG. He is currently a director for TopBuild Corp. where he serves on the Audit (Chairman), Compensation and Governance Committees, and for Delphi Technologies PLC where he serves on the Audit (Chairman) and Finance Committees. Mr. Cantie is a certified public accountant and holds a Bachelor of Science degree from the State University of New York at Buffalo.

              Mr. Cantie brings to the Board more than 30 years of financial and operating experience primarily in the industrials sector, which, along with his tenure at a major accounting firm, provide a diversified knowledge base and additional perspectives to the Board.

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              Director Independence Determination.  Under our Corporate Governance Guidelines and the NYSE corporate governance rules for listed companies, a director is not independent unless the Board affirmatively determines that he or she does not have a direct or indirect material relationship with us or any of our subsidiaries. In addition, the director must meet the bright-line test for independence set forth by the NYSE rules. Our Corporate Governance Guidelines define independence in accordance with the independence definition in the current NYSE rules. Our Corporate Governance Guidelines require the Board to review the independence of all directors at least annually. In the event a director has a relationship with the Company that is relevant to his or her independence and is not addressed by the objective tests set forth in the NYSE independence definition, the Board will determine, considering all relevant facts and circumstances, whether such relationship is material.

              Our Board has affirmatively determined that each of Messrs. Cantie, Gardner, Lance, Murphy, Simpkins and Wunning and Ms. Wade is independent under the guidelines for director independence set forth in the Corporate Governance Guidelines and under all applicable NYSE rules, including with respect to applicable committee membership. Our Board also has determined that each of the members of the Audit Committee, Messrs. Cantie, Gardner and Murphy and Ms. Wade, is "independent" for purposes of Section 10A(m)(3) of the Securities Exchange Act of 1934, as amended (the "Exchange Act").

              In making its independence determinations, the Board considered and reviewed all information known to it, including information identified through annual directors' questionnaires.

              Board Leadership.  The Board directs and oversees the management of the business and affairs of the Company in a manner consistent with the best interests of the Company. The Board's responsibility is one of oversight, and in performing its oversight role, the Board serves as the ultimate decision-making body of the Company, except for those matters reserved to or shared with our stockholders.

              In accordance with our Corporate Governance Guidelines, the Board selects the Company's Chairman and the Company's CEO in any way it considers in the best interests of the Company and, accordingly, does not have a policy on whether the roles of Chairman and CEO should be separate or combined and, if separate, whether the Chairman should be selected from the independent directors. We believe that the separation of the Chairman of the Board and CEO positions is appropriate corporate governance for us as this time. Accordingly, Mr. Lance serves as the Chairman of the Board while Mr. Hill serves as our CEO. Our Board believes that this structure best encourages the free and open dialogue of differing views and provides for strong checks and balances.

              Executive Sessions and Communications with Directors.  The Board's independent directors meet at regularly scheduled executive sessions without management present. Mr. Lance presides at executive sessions of independent directors.

              Stockholders and other interested parties may communicate with the Board by writing to the Chief Legal Officer, Summit Materials, Inc., 1550 Wynkoop Street, 3rd Floor, Denver, Colorado 80202. Written communications may be addressed to the Chairman of the Board, the chairperson of any of the Audit, Corporate Governance and Nominating, and Compensation Committees, or to the non-management or independent directors as a group. The Chief Legal Officer will forward such communications to the appropriate party.

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              Risk Oversight.  The Board exercises direct oversight of strategic risks to the Company. The Audit Committee reviews guidelines and policies governing the process by which senior management assesses and manages the Company's exposure to risk, including the Company's major financial and operational risk exposures and the steps management takes to monitor and control such exposures. The Compensation Committee oversees risks relating to the Company's compensation policies and practices. Each committee charged with risk oversight reports to the Board on those matters.

              With respect to cybersecurity risk oversight, our Board and our Audit Committee receive updates from our information technology team to assess the primary cybersecurity risks facing the Company and the measures the Company is taking to mitigate such risks. In addition to such updates, our Board and our Audit Committee receive updates from management as to changes to the Company's cybersecurity risk profile or significant newly identified risks.

              Corporate Governance Documents.  Please visit our investor relations website at investors.summit-materials.com/govdocs, "Governance Documents," for additional information on our corporate governance, including:

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our Corporate Governance Guidelines;



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our Code of Business Conduct and Ethics; and



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the charters approved by the Board for the Audit Committee, the Compensation Committee and the Nominating and Corporate Governance Committee.

              The Board meets regularly during the year and holds special meetings and acts by unanimous written consent whenever circumstances require. During 2017, there were five meetings of the Board. Each director attended at least 75% of the aggregate of the total number of meetings of the Board (held during the period for which he or she was a director) and the total number of meetings held by all committees on which he or she served (during the periods that he or she served) during 2017. In addition, directors are expected to make every effort to attend any meetings of stockholders. All of our directors attended the 2017 Annual Meeting of Stockholders.

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              The Board has established an Audit Committee, a Compensation Committee and a Nominating and Corporate Governance Committee. The Committees keep the Board informed of their actions and provide assistance to the Board in fulfilling its oversight responsibility to stockholders. The table below provides current membership information as well as meeting information for the last fiscal year.

              The functions performed by these Committees, which are set forth in more detail in their charters, are summarized below.

Our Audit Committee is responsible for, among other things:

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selecting and hiring our independent registered public accounting firm, and approving the audit and non-audit services to be performed by our independent registered public accounting firm;



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assisting the Board in evaluating the qualifications, performance and independence of our independent registered public accounting firm;



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assisting the Board in monitoring the quality and integrity of our financial statements and our accounting and financial reporting;



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assisting the Board in monitoring our compliance with legal and regulatory requirements;



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reviewing the adequacy and effectiveness of our internal control over financial reporting;

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assisting the Board in monitoring the performance of our internal audit function;



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reviewing with management and our independent registered public accounting firm our annual and quarterly financial statements;



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establishing procedures for the receipt, retention and treatment of complaints received by the Company regarding accounting, internal accounting controls or auditing matters and the confidential, anonymous submission by our employees of concerns regarding questionable accounting or auditing matters; and



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preparing the Audit Committee Report that the rules and regulations of the SEC require to be included in our annual proxy statement.

Our Compensation Committee is responsible for, among other things:

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reviewing and approving or making recommendations to the Board with respect to, corporate goals and objectives relevant to the compensation of our Chief Executive Officer, evaluating his/her performance in light of those goals and objectives and determining and approving his/her compensation level based on such evaluation;



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reviewing and approving, or making recommendations to the Board with respect to, the compensation of our other executive officers, including annual base salary, bonus, equity-based incentives and other benefits;



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reviewing and recommending the compensation of our directors;



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reviewing and discussing annually with management our "Compensation Discussion and Analysis" disclosure required by SEC rules;

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•

preparing the Compensation Committee Report required by the SEC to be included in our annual proxy statement; and



•

reviewing and making recommendations with respect to our equity compensation plans.

Our Nominating and Corporate Governance Committee is responsible for, among other things:

•

assisting our Board in identifying prospective director nominees and recommending nominees to the Board;



•

overseeing the evaluation of the Board and management;



•

reviewing and advising the Board on developments in corporate governance practices;



•

developing and recommending a set of corporate governance guidelines; and



•

recommending members for each committee of our Board.

              The Nominating and Corporate Governance Committee identifies individuals believed to be qualified as candidates to serve on the Board and selects, or recommends that the Board select, the nominees for all directorships to be filled by the Board or by our stockholders at an annual or special meeting.

              In identifying candidates for membership on the Board, the Committee takes into account all factors it considers appropriate, which may include:

•

individual qualifications, including strength of character, mature judgment, familiarity with the Company's business and industry, independence of thought and an ability to work collegially; and



•

all other factors the Committee considers appropriate, which may include age, diversity of background, existing commitments to other businesses, potential conflicts of interest with other pursuits, legal considerations such as antitrust issues, corporate governance background, various and relevant career experience, relevant technical skills, relevant business or government acumen, financial and accounting background, executive compensation background and the size, composition and combined expertise of the existing Board.

              Although the Nominating and Corporate Governance Committee considers diversity of viewpoints, background and experiences, the Company does not have a formal diversity policy. The Committee also

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may consider the extent to which the candidate would fill a present need on the Board. When evaluating whether to re-nominate existing directors, the Committee considers matters relating to the retirement of current directors, as well as the performance of such directors.

              The Nominating and Corporate Governance Committee evaluates director candidates recommended by stockholders on the same basis as it considers other nominees. Any recommendation submitted to the Secretary should be in writing and should include any supporting material the stockholder considers appropriate in support of that recommendation, but must include information that would be required under the rules of the SEC to be included in a proxy statement soliciting proxies for the election of such candidate and the written consent of the candidate to serve as one of our directors, if elected. Stockholders wishing to propose a candidate for consideration may do so by submitting the above information to the attention of the Secretary, Summit Materials, Inc., 1550 Wynkoop Street, 3rd Floor, Denver, Colorado 80202. All recommendations for nomination received by the Secretary that satisfy the requirements of our Amended and Restated Bylaws (the "Bylaws") relating to such director nominations will be presented to the Nominating and Corporate Governance Committee for its consideration. Please see the section entitled "Proposals of Stockholders" for information regarding the advance notice provisions applicable to stockholder director nominations set forth in our Bylaws.

              During 2017, the members of the Compensation Committee were Messrs. Simpkins, Lance, Gardner and Wunning, none of whom was, during the fiscal year, an officer or employee of the Company and none of whom has ever served as an officer of the Company. During 2017, none of our executive officers served as a director or member of the compensation committee (or other committee serving an equivalent function) of any other entity whose executive officers served on our Compensation Committee or the Board.

              Our Code of Business Conduct and Ethics applies to all of our officers, directors and employees, including our principal executive officer, principal financial officer and principal accounting officer, or persons performing similar functions and is posted on our website. Our Code of Business Conduct and Ethics is a "code of ethics," as defined in Item 406(b) of Regulation S-K. We will make any legally required disclosures regarding amendments to, or waivers of, provisions of our Code of Business Conduct and Ethics on our website. The information contained on, or accessible from, our website is not part of this Proxy Statement by reference or otherwise.

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INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

              Representatives of KPMG are expected to attend the Annual Meeting and will have an opportunity to make a statement and to respond to appropriate questions from stockholders.

              Consistent with SEC and PCAOB requirements regarding auditor independence, the Audit Committee has responsibility for appointing, setting compensation for and overseeing the work of, the independent registered public accounting firm. In recognition of this responsibility, the Audit Committee has established a policy to pre-approve all audit and permissible non-audit services provided by the independent registered public accounting firm.

              Prior to engagement of the independent registered public accounting firm for the next year's audit, management will submit to the Audit Committee for approval a list of services and related fees expected to be rendered during that year within each of the following four categories of services:

•

Audit services include audit work performed on the financial statements and internal control over financial reporting, as well as work that generally only the independent registered public accounting firm can reasonably be expected to provide, including comfort letters, statutory audits and discussions surrounding the proper application of financial accounting and/or reporting standards.

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•

Audit-Related services are for assurance and related services that are traditionally performed by the independent registered public accounting firm, including due diligence related to mergers and acquisitions, employee benefit plan audits and special procedures required to meet certain regulatory requirements.



•

Tax services include all services, except those services specifically related to the financial statements, performed by the independent registered public accounting firm's tax personnel, including tax analysis; assisting with coordination of execution of tax-related activities, primarily in the area of corporate development; supporting other tax-related regulatory requirements; tax planning; and tax compliance and reporting.



•

All Other services are those services not captured in the Audit, Audit-Related or Tax categories.

              Prior to engagement, the Audit Committee pre-approves independent registered public accounting firm services within each category and the fees of each category are budgeted. The Audit Committee requires the independent registered public accounting firm and management to report actual fees versus the budget periodically throughout the year by category of service. During the year, circumstances may arise when it may become necessary to engage the independent registered public accounting firm for additional services not contemplated in the original pre-approval categories. In those instances, the Audit Committee requires specific pre-approval before engaging the independent registered public accounting firm.

              The Audit Committee may delegate pre-approval authority to one or more of its members. The member to whom such authority is delegated must report, for informational purposes only, any pre-approval decisions to the Audit Committee at its next scheduled meeting. All of the services in the table below were pre-approved by the Audit Committee.

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(1)

Represents the aggregate fees billed for professional services by KPMG for the audit of our financial statements, reviews of our quarterly financial statements and services associated with other SEC filings, including registration statements. Fees related to registration statements totaled $115,000 in 2017 and $598,000 in 2016.

(2)

Represents the aggregate fees billed for professional services by KPMG in connection with routine tax compliance, general tax consulting services and services related to state tax audits. Tax fees related to registration statements totaled $4,000 in 2016.

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BENEFICIAL OWNERSHIP OF SHARES

              The following table sets forth the beneficial ownership of shares of our Class A Common Stock and LP Units by (1) each person known to us to beneficially own more than 5% of any class of the outstanding voting securities of the Company, (2) each of our directors and NEOs and (3) all of our directors and executive officers as a group. Percentage of beneficial ownership of (1) Class A Common Stock is based upon 111,228,077 shares issued and outstanding and (2) LP Units is based upon 114,813,591 LP Units outstanding (including 111,228,077 LP Units held by the Company), in each case as of March 19, 2018. Percentage of combined voting power is based upon 114,560,343 votes represented by outstanding securities, consisting of (1) 111,228,077 shares of Class A Common Stock issued and outstanding and (2) 3,332,266 LP Units outstanding and eligible to vote, excluding LP Units held by the Company, in each case as of March 19, 2018. The Company is the general partner of Summit Materials Holdings L.P. ("Summit Holdings"), which indirectly owns 100% of the limited liability interests of Summit Materials, LLC ("Summit LLC"). Except as otherwise noted, (i) the information is as of March 19, 2018, and (ii) the address of each beneficial owner is c/o Summit Materials, Inc., 1550 Wynkoop Street, 3rd floor, Denver, Colorado 80202. Beneficial ownership is determined in accordance with the rules and regulations of the SEC.

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EXECUTIVE COMPENSATION

              The following Compensation Discussion and Analysis ("CD&A") describes our 2017 executive compensation structure, earned by or paid to the following named executive officers ("NEOs").

              In October 2017, the Company announced that Douglas C. Rauh would leave his role as the Company's Executive Vice President and Chief Operating Officer, effective December 30, 2017. In December 2017, the Company announced that Mr. Rauh entered into an Agreement and Release (the "Agreement and Release") dated December 15, 2017 with Summit Holdings and, solely for certain purposes specified therein, the Company, in connection with his departure from the Company. The terms of the Agreement and Release are described below under "Potential Payments Upon Termination or Change in Control." In January 2018, the Company announced that Karl H. Watson Jr. had been appointed Executive Vice President and Chief Operating Officer of the Company.

              Highlights of our 2017 business achievements included the following:

•

Full-year organic sales volumes of aggregates increased 3.4%.

•

Full-year organic sales volumes of cement increased 5.8%.

•

Full-year net income increased 331.2% to $121.83 million.

•

Full-year operating income increased 42.8% to $220.9 million.

•

Full-year adjusted EBITDA* increased 17.4% to $435.8 million.

*

See "Reconciliation of Non-GAAP Measure to GAAP" on Annex A.

              The Compensation Committee designs the executive compensation program to deliver pay in accordance with corporate, segment, safety and individual performance. A large percentage of total target compensation is at risk through long-term equity awards and annual cash incentive awards. These awards are linked to performance measures that correlate with long-term stockholder value creation. The mix of

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total direct compensation at target for 2017 for our CEO and the average of our other NEOs is shown in the charts below.

              In 2017, our executive compensation structure consisted of four primary components: base salary; annual cash incentives; long-term equity incentives; and traditional health/welfare plans. We eliminated substantially all perquisites in 2017.

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Our Compensation Philosophy

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              The Compensation Committee approved the following compensation targets for 2017:

              In 2017, the Compensation Committee considered the outcome of the stockholder advisory vote on 2016 executive compensation when making decisions relating to the compensation of our NEOs and our executive compensation program and policies. Our stockholders voted at our 2017 annual meeting, in a nonbinding advisory vote, on the 2016 compensation paid to our NEOs. Our stockholders overwhelmingly (96%) approved the compensation of our NEOs. Based on the level of support, the Compensation Committee determined that stockholders generally support our compensation practices. The Compensation Committee intends to continue to consider the views of our stockholders when designing, reviewing and administering the Company's compensation programs and policies.

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Timing of Compensation Decisions

              Pay recommendations for our executives, including the NEOs, are typically made by the Compensation Committee at its first scheduled meeting of the fiscal year, typically held in February around the same time we report our fourth quarter and year-end financial results for the preceding fiscal year and provide our financial guidance for the upcoming year (the "February meeting"). This timing allows the Compensation Committee to have a complete financial performance picture prior to making compensation decisions.

              Decisions with respect to prior year performance, as well as annual equity awards, base salary increases and target performance levels for the current year are typically made at the February meeting. Any equity awards recommended by the Compensation Committee at this meeting are reviewed by the Board and, if approved, are dated on the date of the Board meeting held later that day or the following day. As such, the Compensation Committee does not time the grants of equity incentives to the release of material non-public information. The exercise price of stock options is the closing price of our common stock on the date of grant.

              The exception is grants to executives who are promoted or hired from outside the Company during the year. These executives may receive compensation changes or equity grants effective or dated, as applicable, as of the date of their promotion, hiring date, or other Board approval date.

Determination of CEO Compensation

              At the February meeting, in executive session without the CEO present, the Compensation Committee also reviews and evaluates CEO performance, and determines performance achievement levels, for the prior fiscal year. The Compensation Committee also reviews competitive compensation data from the peer group companies. The Compensation Committee typically approves, or presents pay recommendations for the CEO to the Board, excluding the CEO, for approval. If applicable, during executive session, the Board conducts its own review and evaluation of the CEO's performance taking into consideration the recommendations of the Compensation Committee.

Base Salary

              Annual base salaries compensate our executive officers for fulfilling the requirements of their respective positions and provide them with a level of cash income predictability and stability with respect to a portion of their total compensation. The Compensation Committee determines base salaries for the NEOs and other executives based on a number of factors, including but not limited to, the Compensation Committee's understanding of executive pay practices, individual performance, Company performance and management recommendations (except with respect to the CEO).

              For 2017, based on a thorough review of competitive market data and internal alignment of total compensation opportunity, the Compensation Committee set the base salaries set forth in the table below. Mr. Brady's adjustment moved his salary closer to similar NEOs at peer companies. The 2017 base salaries for Messrs. Hill, Harris, Evans, and Rauh also reflect a one-time salary adjustment that was provided in

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connection with the elimination of substantially all perquisites in 2017. Mr. Brady did not previously receive significant perquisites.

Annual Cash Incentives

              Each NEO was eligible to earn an annual incentive under our Short-Term Incentive Plan (the "STIP") based upon the achievement of performance targets approved by the Board at the February meeting.

              2017 Target Annual Incentive Award Opportunities. At the start of each fiscal year, the Board approves annual incentive compensation targets, as a percentage of base salary, based on the understanding of the Board of competitive executive pay practices, management's recommendations and other relevant factors. The 2017 annual incentive targets, as a percentage of base salary, for our NEOs were consistent with our 2016 targets and were as follows:

              2017 Annual Incentive Metrics. For corporate NEOs (Messrs. Hill, Brady, Harris and Rauh), the performance metrics approved for fiscal 2017 were (i) corporate earnings before interest, taxes, depreciation, depletion and amortization ("EBITDA"), as defined by the Board, which is defined as EBITDA, as adjusted to exclude accretion, loss on debt financings, tax receivable agreement expense, income from discontinued operations and certain non-cash and non-operating items plus the EBITDA contribution of certain recent acquisitions, (ii) operating cash flow, which approximates annual cash flow exceeding capital transactions and acquisitions, (iii) safety metrics, and (iv) personal objectives, which vary by individual. Mr. Brady was also subject to acquisition related metrics, including acquisition spend and acquisition EBITDA performance. For Mr. Evans, the approved performance metrics included (i) corporate EBITDA, (ii) segment EBITDA, (iii) segment cash flow, (iv) segment safety and (v) personal objectives. The Board has discretion to adjust the financial metrics to reflect merger, acquisition or divestiture activity during the fiscal year. In 2017, as further discussed below, the metrics were adjusted to reflect acquisitions completed during the year and the financial impact of Hurricane Harvey on the Company's operations.

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              For 2017, performance metrics and weightings were as follows:

              Performance / Payout Percentage.    The achievement factor for each of the performance metrics was determined by multiplying the weight attributed to each performance metric by the applicable payout percentage for each metric. For corporate EBITDA and operating cash flow, payout percentages were determined by calculating actual achievement against the target amount based on a pre-established scale.

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Payout percentages for actual performance between the specified threshold levels and 105% of target, and between 105% of target and the maximum levels, were adjusted on a linear basis. The following table shows the payout percentages associated with various levels of achievement of corporate EBITDA:

              The following table shows the payout percentages associated with various levels of achievement of corporate operating cash flow:

              For Mr. Evans, Segment EBITDA and Segment Cash Flow payout percentages were determined by calculating actual achievement against the target amount based on a pre-established scale. Payout percentages for actual performance between the specified threshold, target and maximum levels were adjusted on a linear basis. The following table shows the payout percentages associated with threshold, target and maximum achievement of Segment EBITDA and Segment Cash Flow:

              The maximum payout opportunities for the safety metrics and personal objectives were 150% of target. For the safety metrics, payout percentages for actual achievement between the specified threshold, target and maximum levels were adjusted on a linear basis. The overall safety metric achievement factor equals the sum of each metric's payout percentage multiplied by its weighting.

              For Mr. Brady, acquisition spend and acquisition EBITDA performance were determined by calculating actual achievement against the target amount based on a pre-established scale. The maximum payout opportunities for the acquisition metrics were 150% of target for actual achievement at 110% of target.

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              2017 Actual Performance.    Actual results for the 2017 annual incentive plan were certified by the Compensation Committee, as follows, based on the performance goals and funding scales approved in the first quarter of 2017:

              The payout percentages for the safety metrics were as follows: corporate safety was 124% of target, resulting in an achievement factor of 12.4% for each NEO other than Mr. Evans; and West Segment safety for Mr. Evans was 72% of target, resulting in an achievement factor of 7.2%. Each of the safety metric targets were set at a challenging level that are consistent with our long-term goals and designed to meet high stockholder expectations.

              Actual annual cash incentive awards are calculated by multiplying each NEO's actual base salary by his target award potential, which was then adjusted by an overall achievement factor based on the combined weighted achievement of the components described above, including an evaluation of each

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NEO's personal objectives. The following table summarizes the 2017 bonuses earned based on actual performance, as compared to the target opportunity for each NEO:

Long-Term Incentives

On-Going Post-IPO Long-Term Incentives

              The Company maintains the Summit Materials, Inc. 2015 Omnibus Incentive Plan (the "Omnibus Incentive Plan") which allows for grants of equity-based awards in the form of stock options, stock appreciation rights, restricted stock and restricted stock units ("RSUs"), performance units, undivided fractional limited partnership interests in Summit Holdings and other stock-based awards. In 2015, the Compensation Committee determined that the size, structure, and value of the pre-IPO grants were sufficient for 2015 and no additional equity grants were made in 2015 in connection with, or after, our IPO.

              In 2016, the Compensation Committee worked with the Independent Compensation Consultant to develop a competitive long-term incentive grant structure as an on-going public company. The Compensation Committee believes in a balanced approach to long-term incentive compensation, with an emphasis on performance-based compensation. The Compensation Committee determined that a similar structure in 2017 was appropriate.

              Our regular ongoing equity incentives for NEOs in 2017 consisted of a balance of performance units (34%), RSUs (33%) and stock options (33%). In 2018, the Committee determined to eliminate stock options from regular ongoing equity incentive grants. Accordingly, our regular ongoing equity incentives for NEOs in 2018 consisted of a balance of performance units (50%) and RSUs (50%). The Committee uses competitive market data from our annual total compensation study to assist with targeted long-term incentive value. In addition, the Committee considers individual performance, potential future contributions to our business, internal equity and management's recommendations.

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Performance Units

              The 2017 performance units focus our executives on the long-term performance of the Company relative to industry peers. The 2017 performance units vest at the end of a three-year performance period, based on our TSR ranking relative to companies that formerly comprised the S&P Building & Construction Select Industry Index ("Relative TSR"), which index was discontinued in 2017, using beginning and ending stock prices based on the trailing 20-day average closing price. The Compensation Committee determined that Relative TSR ranking against an industry index aligns management with stockholder value creation and provides incentive to achieve the Company's long-term strategy.

              The performance period for the performance units granted in February 2017 began on January 1, 2017 and ends on December 31, 2019. Following the completion of the three-year performance period, the Compensation Committee will determine earned amounts based on our Relative TSR ranking versus the companies that formerly comprised the S&P Building & Construction Select Industry Index. This peer group is separate and distinct from the peer group used to evaluate and set NEO compensation levels discussed under "—Compensation Decision Process—Role of Peer Companies and Competitive Market Data." The Relative TSR peer group represents a broader array (approximately 130 companies) of industry peers competing for stockholders and investors and avoids subjectivity as it was independently constructed by Standard & Poor's.

              The 2017 grants will be earned based on the schedule below. Earned amounts will be interpolated on a straight-line basis for performance between the stated percentiles.

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              See "—Potential Payments Upon Termination or Change in Control" for a description of the potential vesting of the NEOs' equity awards that may occur in connection with certain termination events and a change in control.

              For 2017, the Compensation Committee set the target pay levels and made the grants set forth in the table below.

2018 Enhancements to Our On-Going Long-Term Incentive Structure

              During 2017, the Compensation Committee worked closely with our Independent Compensation Consultant to enhance our long-term incentive structure for our executive officers. The following modifications were approved for the 2018 grant cycle:

•

Relative TSR peer group for performance units: The S&P Building & Construction Select Industry Index was discontinued in 2017. Outstanding grants will continue to use the companies comprising that index. For the 2018 grant cycle, the Committee approved a new Relative TSR peer group defined as the Materials and Capital Goods companies (consisting of companies in GICS industry groups 2010 and 1510—, which is the same as the previous peer group), from the S&P 400 Midcap Index. The new Relative TSR peer group consists of approximately 68 companies with similar revenues and market capitalization as the Company.



•

Eliminated stock options and increased the weight of performance units and RSUs: The Committee approved the elimination of stock options and increased the weight on performance units and RSUs. The new approach beginning with 2018 equity grants will be 50% performance units and 50% RSUs.

Retirement, Perquisites and Other Benefits

              We have a tax-qualified contributory retirement plan established to qualify as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code of 1986, as amended (the "Code"). The plan covers all U.S. employees, including our NEOs, who are limited to their annual tax deferred contribution limit as allowed by the Internal Revenue Service (the "IRS"). We provide for matching contributions to the plan, including 100% of pre-tax employee contributions, up to 4% of eligible compensation. Employer contributions vest immediately.

              The Company also offers the members of a select group of management or highly compensated employees, including the NEOs, the opportunity to supplement their retirement savings through the Summit Materials Deferred Compensation Plan (the "DCP"). An eligible participant in the DCP may elect to defer up to 50% of such participant's base salary compensation and up to 100% of such participant's designated discretionary bonus award compensation and annual incentive award compensation. The DCP also permits Company-provided credits to participants' accounts, but no such credits are currently being

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made. Additional information about the DCP is reflected in "—2017 Non-Qualified Deferred Compensation" below.

              Beginning in 2017, we eliminated substantially all perquisites to our NEOs and senior executives. A one-time salary adjustment was provided to offset the changes.

Change in Control and Severance Arrangements

              On December 15, 2017, the Board, on the recommendation of the Compensation Committee, approved an Executive Severance Plan (the "Severance Plan") in order to standardize severance provisions for certain executive officers that had been governed by separate legacy arrangements. All of our NEOs, other than Mr. Rauh, who left the Company at the end of the 2017, participate in the Severance Plan. In connection with implementing the Severance Plan, all participants in the Severance Plan waived the provisions of any applicable employment agreement that would have applied under the conditions set forth under the Severance Plan. See "Potential Payments Upon Termination or Change in Control" for a description of the Severance Plan.

              Also on December 15, 2017, Mr. Rauh entered into the Agreement and Release in connection with his departure. In recognition of Mr. Rauh's service to the Company, the Agreement and Release provided for the beneficial modification of the terms of Mr. Rauh's outstanding equity awards. The terms of the Agreement and Release are described below under "Potential Payments Upon Termination or Change in Control."

Stock Ownership Guidelines

              We have established stock ownership guidelines for our CEO, officers reporting to the CEO, and directors. The approved guidelines are as follows:

•

CEO: 6x base salary



•

Officers reporting to the CEO: 2.5x base salary



•

Directors: 3x annual cash retainer

              Participants are expected to comply with the ownership requirements within five years of the later of (x) December 12, 2015 and (y) an appointment to a qualified position. Once the ownership requirements have been satisfied, future declines in share price will not affect compliance so long as the participant holds the number of equity interests he or she had at the time he or she achieved the expected ownership level. As of December 30, 2017, all of our executive officers have met or exceeded the ownership expectations under the guidelines.

              The following components satisfy the ownership guidelines: Equity interests owned directly or indirectly (e.g., by or with a spouse or held in trust for the individual or one or more family members of the individual), equity interests, including LP Units and unvested RSUs, held in qualified or nonqualified savings, profit sharing, or deferred compensation accounts, value of in-the-money spread of shares underlying vested but unexercised stock options and value of in-the-money spread of shares underlying

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vested but unexercised warrants. Annually, the Compensation Committee monitors participants' compliance with these guidelines.

Incentive Compensation Recoupment ("Clawback") Policy

              Each of the RSU, stock option and performance unit award agreements under the Omnibus Incentive Plan generally provides that if a restrictive covenant violation occurs or the Company discovers after a termination of employment or services that grounds existed for "cause" (as defined in the Omnibus Incentive Plan) at the time thereof, then the participant shall be required, in addition to any other remedy available (on a non-exclusive basis), to pay to the Company, within ten business days of the Company's request to the participant therefor, an amount equal to the aggregate after-tax proceeds (taking into account all amounts of tax that would be recoverable upon a claim of loss for payment of such proceeds in the year of repayment) the participant received upon the sale or other disposition of, or distributions in respect of, the equity award thereunder and any shares issued in respect thereof (minus, in the case of options, the aggregate cost (if any) of the shares). Without limiting the foregoing, all awards are subject to reduction, cancellation, forfeiture or recoupment to the extent necessary to comply with applicable law. Our policy will be updated to comply with the SEC's final regulations as part of the Dodd-Frank Act.

              Our governance policies and compensation structure are not reasonably likely to have a material adverse effect on the Company. The Independent Compensation Consultant and management delivered a compensation risk assessment report to the Compensation Committee in 2017. The following features of our program mitigate risk:

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              The following table sets forth the compensation of our NEOs for the fiscal years ended 2017, 2016 and 2015, and their respective titles as of December 30, 2017.

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              The following table provides supplemental information relating to grants of plan-based awards to help explain information provided above in our Summary Compensation Table.

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              Messrs. Hill and Harris each have employment agreements and Messrs. Brady and Evans have signed offers of employment. Their employment agreements and offers of employment provide for base salary subject to annual adjustment by the Board, an annual incentive award, participation in Company-sponsored broad-based and executive benefit plans and such other compensation as may be approved by the Board. In connection with implementing the Severance Plan, Messrs. Hill and Harris waived the provisions in their employment agreements that would have applied under the conditions set forth in the Severance Plan, other than any provisions in their employment agreements which were intended to survive the termination of such employment agreements.

Pre-IPO Long-Term Incentive Awards

              Prior to the Company's IPO in March 2015, the equity-based long-term incentive program consisted of Class D interests. In connection with the Company's IPO in March 2015, the limited partnership agreement of Summit Holdings was amended and restated to, among other things, modify its capital structure by creating LP Units (the "Reclassification"). Immediately following the Reclassification, 69,007,297 LP Units were outstanding, which were reclassified from previously issued Class A-1, Class B-1, Class C, Class D-1 and Class D-2 interests. The Class A-1, Class B-1 and Class C interests, which were issued in respect of pre-IPO investments and not related to employee compensation, were fully vested as of the Reclassification. A portion, but not all, of the Class D-1 interests were vested, and none of the Class D-2 interests were vested. Accordingly, vested and unvested Class D interests were converted into vested and unvested LP Units, respectively. The vesting terms were substantially similar to those applicable to the unvested Class D interests immediately prior to the Reclassification. As of their respective grant date, approximately half of the Class D-1 interests were time-vesting interests and approximately half of the D-1 interests and all of the D-2 interests were performance-vesting interests.

              In addition, in substitution for part of the economic benefit of the Class C and Class D interests that was not reflected in the conversion of such interests to LP Units, warrants were issued to holders of Class C interests to purchase an aggregate of 160,333 shares of Class A Common Stock, and options were issued to holders of Class D interests to purchase an aggregate of 4,358,842 shares of Class A Common Stock ("Leverage Restoration Options"). The exercise price of the warrants and Leverage Restoration Options was the IPO price of $18.00 per share. The Leverage Restoration Options were granted under the Omnibus Incentive Plan. All Leverage Restoration Options vest over four years at a rate of 25% of the award on each of the first four anniversaries of the Reclassification, subject to the employee's continued employment through the applicable vesting date. The Leverage Restoration Options that correlated to performance-vesting interests vested only if both the relevant return multiple was achieved and the four year time-vesting condition was satisfied.

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              On August 9, 2016, our Board upon the recommendation of the Compensation Committee, determined that it was in the best interest of the Company and its stockholders to remove the 3.00 times investment return condition on the approximately 23% remaining pre-IPO performance-vesting LP Units and Leverage Restoration Options. As a result, all pre-IPO performance-vesting LP Units are now fully vested and the performance-vesting Leverage Restoration Options continue to be subject to the same four-year time vesting condition as the time-vesting Leverage Restoration Options.

              In 2018, a sub-committee of the Compensation Committee consisting of members that do not hold LP Units (the "Sub-Committee") determined that the administrative burden and costs associated with the monthly vesting of the remaining time-vesting LP Units outweighed any remaining retention incentive associated with the awards. As a result, the Sub-Committee determined it was appropriate to accelerate the vesting of all the remaining time-vesting LP Units held by our employees. The incremental fair value computed in accordance with FASB ASC Topic 718 with respect to this modification for each of the NEOs was not material.

              All outstanding equity grants associated with the Reclassification are summarized in the table titled "Outstanding Equity Awards at 2017 Fiscal Year-End."

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              A summary of the outstanding equity awards for each NEO as of December 30, 2017 is as follows:

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              The following table provides information regarding the amounts recognized by our NEOs upon the exercise of stock options and the vesting of stock awards during 2017.

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              The following table provides information regarding contributions, earnings and balances for our NEOs with respect to our DCP, the only defined contribution or other plan that provides for the deferral of compensation on a basis that is not tax-qualified.

              Pursuant to the DCP, an eligible participant may elect to defer up to 50% of such participant's base salary compensation (in 5% increments) and up to 100% of such participant's designated discretionary bonus award compensation and annual incentive award compensation (in 5% increments). Deferral elections are generally made by participants prior to the close of the taxable year preceding the taxable year for which the applicable compensation is earned. The DCP also permits Company-provided credits to participants' accounts, but no such credits are currently being made. Participants are permitted to make individual investment elections that will determine the rate of return on their deferral amounts under the DCP and may change their investment elections at any time. Deferrals are only deemed to be invested in the investment options selected. Participants have no ownership interest in any of the funds as investment elections are used solely to measure the amounts of investment earnings or losses that will be credited or debited to the participants' accounts on the Company's books and records. Investment funds are valued each day that the NYSE is open for trading. Participant deferrals under the DCP and the earnings thereon are always 100% vested.

              The table below shows the funds in which our NEOs invested during 2017, and their rate of return from January 1, 2017 through December 31, 2017.

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              A DCP participant may elect, at the time of such participant's deferral elections, to receive benefit distributions upon (i) separation from service with the Company or (ii) following the earlier of (a) a specified date that occurs no earlier than at least three years from the end of the calendar year in which the deferred compensation is credited or (b) separation from service with the Company. Additionally, a DCP participant may elect, at the time of such participant's deferral elections, to receive benefit distributions in the form of (i) a single lump sum payment or (ii) for distributions following retirement, annual installments with an installment term of between two and 15 years. A participant may elect to change the benefit distribution date and/or form under certain circumstances specified in the DCP. In addition, in the event of certain unforeseeable emergencies, a participant may apply for immediate distribution in an amount necessary to satisfy such financial hardship and the tax liability attributable to such distribution. In the event of a participant's death or disability, the entire value of such participant's account will be distributed in a single lump sum.

Executive Severance Plan

              The Board, upon the recommendation of the Compensation Committee, adopted the Severance Plan in December 2017, which provides severance benefits to certain executive officers of the Company and its affiliates in the event that an eligible employee experiences a termination of employment by the Company without "cause" (and other than due to death or disability) or by the employee as a result of a "constructive termination" (as such terms are defined in the Severance Plan) (each, a "Qualifying Termination"). In the event that a Qualifying Termination occurs during the two-year period beginning on the date of a change in control (each such termination, a "Qualifying Change in Control Termination"), the Severance Plan provides enhanced severance benefits. In connection with implementing the Severance Plan, all participants in the Severance Plan waived the provisions of any applicable employment agreement that would have applied under the conditions set forth under the Severance Plan, other than any provisions in such employment agreements which were intended to survive the termination of such employment agreement.

              Each participant in the Severance Plan (a "Participant") is designated as a Tier 1 Participant or Tier 2 Participant. Tier 1 Participants are limited to the Chief Executive Officer. Tier 2 Participants are limited to Executive Vice Presidents. Accordingly, Mr. Hill is a Tier 1 Participant and Messrs. Brady, Harris and Evans are each Tier 2 Participants.

              In the event of a Qualifying Termination, Participants are provided with the following payments and benefits:

•

a pro-rata payment representing the amount otherwise payable under the annual bonus program for the fiscal year in which termination of the Participant's employment occurs, based on actual performance and payable concurrently with cash bonus payments to other employees (but in all events on or about March 15 of the immediately following fiscal year) (a "Pro-Rata Bonus"), and to the extent not previously paid, the amount otherwise payable under the annual bonus program for the immediately preceding fiscal year, payable concurrently with cash bonus payments to other employees (a "Prior Year Bonus");



•

a cash payment of (i) for a Tier 1 Participant, 2.5 times the Participant's annual base salary, payable over a period of 30 months, and (ii) for a Tier 2 Participant, 2 times the Participant's annual base salary, payable over a period of 24 months; and

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•

a cash payment in an amount equal to the total amount of the monthly COBRA insurance premiums for participation in the life, health, dental and disability benefit programs of the Company in which the Participant participated as of the date of termination, payable monthly in accordance with the Company's payroll practices, (i) for a Tier 1 Participant, for up to 30 months, and (ii) for a Tier 2 Participant, for up to 24 months (the "COBRA Benefits").

              In the event of a Qualifying Change in Control Termination, Participants are provided with the following payments and benefits:

•

a Pro-Rata Bonus, and, if applicable, a Prior Year Bonus;



•

a cash payment of (i) for a Tier 1 Participant, 2.5 times the sum of the Participant's annual base salary and target annual bonus, and (ii) for a Tier 2 Participant, 2 times the sum of the Participant's annual base salary and target annual bonus, in each case of (i) and (ii), payable in a lump sum no later than the 60^th day following the date of termination; and



•

the COBRA Benefits.

              The payments and benefits provided under the Severance Plan are subject to each Participant's execution and delivery of a release of claims and each Participant's compliance with non-competition, non-disparagement, non-solicitation and confidentiality covenants applicable pursuant to each Participant's Participation Notice and Agreement under the Severance Plan. The non-disparagement and confidentiality covenants each have an indefinite term and the non-competition and non-solicitation covenants each have a term of 12 months following the Participant's date of termination (18 months for Mr. Hill). Additionally, the Severance Plan provides that if a Participant is subject to an excise tax under Section 4999 of the Code, then the payments and benefits the Participant receives may be reduced so that the excise tax does not apply; however, such reduction will only occur if it results in the receipt of a greater after-tax severance than would otherwise be provided.

Treatment of Long-Term Incentive Awards Upon Termination or Change in Control

              Each of the RSUs, stock options and performance units granted in 2017 is subject to restrictive covenants related to post-employment (i) employee, client and consultant non-solicitation and (ii) non-competition, in each case for 12 months following any termination of employment and indefinite covenants covering confidentiality and non-disparagement (participant only). Further, the equity awards and all proceeds therefrom are generally subject to the Company's clawback policy, as in effect from time to time, to the extent the participant is a director or "officer" as defined under Rule 16a-1(f) of the

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Exchange Act. Additional provisions regarding the treatment of the equity awards upon a termination of employment are outlined in the table below.

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Termination Benefits Table

              The following table describes the potential payments and benefits under the Company's Severance Plan and equity award agreements to which the NEOs would have been entitled assuming an eligible termination of employment or change in control occurred on December 29, 2017, the last business day of fiscal 2017. A description of the provisions governing such payments under our agreements and any material conditions or obligations applicable to the receipt of payments are described above under "Executive Severance Plan" and "Treatment of Long-Term Incentive Awards Upon Termination or Change in Control."

              The amounts shown in the table do not include payments and benefits to the extent they are provided generally to all salaried employees upon termination of employment and do not discriminate in scope, terms or operation in favor of the NEOs. These include accrued but unpaid salary and distributions of vested plan balances under our 401(k) savings plans.

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Departure of Douglas C. Rauh

              In connection with the departure of Douglas C. Rauh, effective December 30, 2017, Mr. Rauh entered into the Agreement and Release with Summit Holdings and, solely for certain purposes specified therein, the Company, which provided for the following:

•

the payment of $1,100,000, payable in regular installments in accordance with Summit Holdings' normal payroll practices through December 31, 2019, representing 2 times his base salary for 2017;



•

the payment of $437,951, payable in accordance with Summit Holdings' normal payroll practices for annual bonuses, without regard to his departure date, representing his annual bonus with respect to fiscal year 2017;



•

monthly COBRA health continuation coverage premiums for up to 24 months following his departure date having an aggregate value equal to $28,872;



•

continued vesting of all outstanding unvested equity awards other than his performance units through the end of the Rauh Consulting Term (defined below); and



•

accelerated vesting, as of the last day of the Rauh Consulting Term, of all outstanding unvested equity awards other than his performance units, so long as the Rauh Consulting Term has not been voluntarily terminated by Mr. Rauh. Any accelerated options will not be exercisable prior to the date such options would have otherwise vested in accordance with the terms of the original award agreement, and will be exercisable for 90 days after such date, after which such options will be forfeited. A prorated portion of Mr. Rauh's outstanding performance units will remain eligible to vest at the end of the performance period in accordance with their terms, based on actual performance.

              The payments and benefits provided for in the Agreement and Release were subject to Mr. Rauh's execution and delivery of a release of claims and his continued compliance with the non-competition, non-disparagement, non-solicitation and confidentiality covenants contained in his employment agreement. The non-disparagement and confidentiality covenants each have an indefinite term and the non-competition and non-solicitation covenants each have a term of 12 months following Mr. Rauh's departure.

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              Additionally, pursuant to the Agreement and Release, beginning on January 1, 2018, Mr. Rauh agreed to provide Summit Holdings with consulting services on a month-to-month basis, unless terminated earlier by either party with 10 business days' prior written notice (such applicable term, the "Rauh Consulting Term"). During the Rauh Consulting Term, Mr. Rauh will be entitled to (i) a monthly consulting fee of $15,000 and (ii) reimbursement of reasonable business expenses and wireless internet and cellular phone expenses incurred by Mr. Rauh in connection with his consulting services.

              The CEO pay ratio figures below are a reasonable estimate calculated in a manner consistent with Item 402(u) of Regulation S-K under the Exchange Act.

              We determined that as of December 5, 2017, our total number of full- and part-time U.S. employees was 5,642 and non-U.S. employees was 265. We chose not to exclude any countries as permitted by SEC regulations, which resulted in 5,907 employees included in the calculation.

              To determine our median employee pay, we chose taxable wages as our consistently applied compensation measure. We then calculated an annual taxable wage for each employee, annualizing pay for those full-time or part-time permanent employees who commenced work during 2017 or who were on leave for a portion of 2017. We used a valid statistical sampling method to identify the group of employees within a 5% range of the estimated median level of taxable wages for our employee population. The historical compensation of this group was then analyzed to identify a median employee whose annual total compensation was reasonably representative of the median annual total compensation in respect of 2017 and was also reasonably likely to remain representative of the median in future years. After identifying the median employee, we calculated the median employee's annual total compensation in accordance with the requirements of the Summary Compensation Table. For 2017, the median employee's annual total compensation was $56,523 and the annual total compensation of our CEO was $4,490,470, which amount varies from his total compensation amount as reflected in the Summary Compensation Table because each of these amounts includes the value of non-discriminatory employer paid health benefits. Accordingly, for 2017, the ratio of CEO pay to median employee pay was 79:1.

              This pay ratio is a reasonable estimate calculated in a manner consistent with SEC rules and the methodology described above. The SEC rules for identifying the median compensated employee and calculating the pay ratio based on such employee's annual total compensation allow companies to adopt a variety of methodologies, to apply certain exclusions, and to make reasonable estimates and assumptions that reflect their compensation practices. As such, the pay ratio reported by other companies may not be comparable to the pay ratio reported above, as other companies may have different employment and compensation practices and may utilize different methodologies, exclusions, estimates and assumptions in calculating their own pay ratios.

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              Prior to 2017, we only paid compensation to directors who were not employed by us or Blackstone. Following the November 2016 secondary offering of Blackstone's shares of our Class A Common Stock, Blackstone ceased to hold any LP Units or shares of our Class A Common Stock. In connection with Blackstone's exit, the Board determined it was appropriate to begin paying compensation to directors who are employed by Blackstone, commencing with fiscal 2017.

              In 2017, all of the Company's non-employee directors (other than Ms. Julia Kahr) received annual cash compensation of $100,009. Ms. Kahr received cash compensation of $16,667 for her service prior to her resignation from the Board effective February 28, 2017. The chairperson of the Board received an additional $150,000 in cash compensation and the respective chairpersons of the Audit Committee, Compensation Committee and Nominating and Corporate Governance Committee (unless such chairperson is also the chairperson of the Board) receive an additional $15,000, $10,000 and $10,000, respectively. Directors who were not employed by us may also receive compensation, from time to time, for service on any special committees of the Board. We reimburse our directors for any reasonable expenses incurred by them in connection with services provided in such capacity.

              In addition, during 2017, all of the Company's non-employee directors (other than Ms. Kahr) received an annual award of RSUs valued at $99,991. A grant of 4,098 RSUs was made to each of Messrs. Lance, Cantie, Gardner, Murphy, Simpkins, and Wunning and Ms. Wade, on February 28, 2017. The RSUs were granted under the Omnibus Incentive Plan, and the terms thereof are outlined in the table below. Further, the RSU awards are subject to the Company's clawback policy, as in effect from time to time.

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              The table below summarizes the compensation paid to non-employee directors for the year ended December 30, 2017.

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CERTAIN RELATIONSHIPS AND RELATED PERSON TRANSACTIONS

              In connection with the IPO, we entered into an Exchange Agreement with the holders of LP Units pursuant to which each holder of LP Units (and certain permitted transferees thereof) may, subject to the terms of the Exchange Agreement, exchange their LP Units for shares of Class A Common Stock on a one-for-one basis, subject to customary conversion rate adjustments for stock splits, stock dividends and reclassifications. The Exchange Agreement also provides that a holder of LP Units will not have the right to exchange LP Units if the Company determines that such exchange would be prohibited by law or regulation or would violate other agreements with the Company or its subsidiaries to which such holder may be subject. The Company may impose additional restrictions on exchange that it determines to be necessary or advisable so that Summit Holdings is not treated as a "publicly traded partnership" for U.S. federal income tax purposes. As a holder exchanges LP Units for shares of Class A Common Stock, the number of LP Units held by the Company is correspondingly increased as it acquires the exchanged LP Units. In accordance with the Exchange Agreement, any holder who surrenders all of its LP Units for exchange must concurrently surrender all shares of Class B Common Stock held by it (including fractions thereof) to the Company.

              In connection with the IPO, we entered into a registration rights agreement with our pre-IPO owners and the former holders of Class B Units of Continental Cement Company, L.L.C. (the "Former CCC Minority Holders") pursuant to which we granted them, their affiliates and certain of their transferees the right, under certain circumstances and subject to certain restrictions, to require us to register under the Securities Act of 1933, as amended (the "Securities Act"), the offering of shares of Class A Common Stock delivered in exchange for LP Units. Under the registration rights agreement, we agreed to register the exchange of LP Units for shares of Class A Common Stock by our pre-IPO owners. In addition, Blackstone had the right to request an unlimited number of "demand" registrations and had customary "piggyback" registration rights. The Former CCC Minority Holders had the right to request one "demand" registration and had customary piggyback registration rights.

              In connection with the IPO, we entered into a tax receivable agreement with the holders of LP Units that provides for the payment to exchanging holders of LP Units of 85% of the benefits, if any, that the Company is deemed to realize as a result of the increases in tax basis resulting from exchanges of LP Units and certain other tax benefits related to entering into the tax receivable agreement, including tax benefits attributable to payments under the tax receivable agreement. Certain current and former holders of LP Units, who include certain of our executive officers and directors, are expected to receive payments under the tax receivable agreement in the future. The increases in tax basis as a result of an exchange of LP Units for shares of Class A Common Stock, as well as the amount and timing of any payments

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under the tax receivable agreement, are difficult to accurately estimate as they will vary depending upon a number of factors, including:

•

the timing of exchanges—for instance, the increase in any tax deductions will vary depending on the fair market value, which may fluctuate over time, of the depreciable or amortizable assets of Summit Holdings at the time of each exchange;



•

the price of shares of our Class A Common Stock at the time of the exchange—the increase in any tax deductions, as well as the tax basis increase in other assets, of Summit Holdings, is directly proportional to the price of shares of our Class A Common Stock at the time of the exchange;



•

the extent to which such exchanges are taxable—if an exchange is not taxable for any reason, increased deductions will not be available;



•

the amount and timing of our income—the Company is required to pay 85% of the cash tax savings as and when realized, if any. If the Company does not have taxable income, the Company is not required (absent a change of control or circumstances requiring an early termination payment) to make payments under the tax receivable agreement for that taxable year because no cash tax savings will have been realized. However, any tax attributes that do not result in realized benefits in a given tax year will likely generate tax attributes that may be utilized to generate benefits in previous or future tax years. The utilization of such tax attributes will result in cash tax savings that will result in payments under the tax receivable agreement; and



•

the effective tax rate—the benefit that the Company realizes is dependent on the tax rate in effect at the time taxable income is generated. For example, at the end of 2017, the Tax Cuts and Jobs Act was enacted into law. Among other things, the federal corporate tax rate was reduced from 35% to 21%. As a result, the value of the additional benefits generated from the exchanges was reduced, and therefore, the tax receivable agreement liability recorded by the Company was also reduced.

              We anticipate funding payments under the tax receivable agreement from cash flows from operations, available cash and available borrowings under our senior secured revolving credit facilities. As of December 30, 2017, we had accrued $331.9 million as tax receivable agreement liability. Other than $0.6 million which was paid in January 2018, the tax receivable agreement liability is a long term liability as no additional payments are expected in the next twelve months.

              In addition, the tax receivable agreement provides that upon certain changes of control, the Company's (or its successor's) obligations would be based on certain assumptions, including that the Company would have sufficient taxable income to fully utilize the deductions arising from the tax deductions, tax basis and other tax attributes subject to the tax receivable agreement. With respect to our obligations under the tax receivable agreement relating to previously exchanged or acquired LP Units and certain net operating losses, we would be required to make a payment equal to the present value (at a discount rate equal to one year LIBOR plus 100 basis points) of the anticipated future tax benefits determined using assumptions (ii) through (v) of the following paragraph.

              Furthermore, the Company may elect to terminate the tax receivable agreement early by making an immediate payment equal to the present value of the anticipated future cash tax savings. In determining such anticipated future cash tax savings, the tax receivable agreement includes several assumptions,

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including that (i) any LP Units that have not been exchanged are deemed exchanged for the market value of the shares of Class A Common Stock at the time of termination, (ii) the Company will have sufficient taxable income in each future taxable year to fully realize all potential tax savings, (iii) the Company will have sufficient taxable income to fully utilize any remaining net operating losses subject to the tax receivable agreement on a straight line basis over the shorter of the statutory expiration period for such net operating losses or the five-year period after the early termination or change of control, (iv) the tax rates for future years will be those specified in the law as in effect at the time of termination and (v) certain non-amortizable assets are deemed disposed of within specified time periods. In addition, the present value of such anticipated future cash tax savings are discounted at a rate equal to LIBOR plus 100 basis points.

              Under the terms of the tax receivable agreement, the Company can terminate the tax receivable agreement at any time, which would trigger a cash payment to the pre-IPO owners. Based upon a $31.44 per share price of our Class A common stock, the closing price of our stock on December 30, 2017 and a contractually defined discount rate of 3.11%, the Company estimates that if it were to exercise its right to terminate the tax receivable agreement, the aggregate amount required to settle the tax receivable agreement would be approximately $282 million.

              The Company holds LP Units in Summit Holdings and is the sole general partner of Summit Holdings. Accordingly, the Company operates and controls all of the business and affairs of Summit Holdings and, through Summit Holdings and its operating entity subsidiaries, conducts our business.

              Pursuant to the limited partnership agreement of Summit Holdings, the Company has the right to determine when distributions will be made to holders of LP Units and the amount of any such distributions. If a distribution is authorized, such distribution will be made to the holders of LP Units pro rata in accordance with the percentages of their respective limited partnership interests.

              No distributions will be made in respect of unvested LP Units and instead such amounts will be distributed to holders of vested LP Units pro rata in accordance with their vested interests. If, from time to time, an unvested LP Unit becomes vested, then, on the next distribution date, all amounts that would have been distributed pro rata in respect of that LP Unit if it had been vested on prior distribution dates will be required to be "caught up" in respect of that LP Unit before any distribution is made in respect of other vested LP Units.

              The holders of LP Units, including the Company, incur U.S. federal, state and local income taxes on their share of any taxable income of Summit Holdings. The limited partnership agreement of Summit Holdings provides for tax distributions to the holders of the LP Units in an amount generally calculated to provide each holder of LP Units with sufficient cash to cover its tax liability in respect of the LP Units. These tax distributions are generally only paid to the extent that other distributions made by Summit Holdings were otherwise insufficient to cover the estimated tax liabilities of all holders of LP Units. In general, these tax distributions are computed based on our estimate of the net taxable income of Summit Holdings allocated to each holder of LP Units multiplied by an assumed tax rate equal to the highest effective marginal combined U.S. federal, state and local income tax rate applicable to an individual or corporate resident in New York, New York (or a corporate resident in certain circumstances). In the year ended December 30, 2017, Summit LLC paid distributions to Summit Holdings totaling $49.7 million, of which $1.8 million was distributed to Summit Holdings' partners, other than the Company, and of which $47.9 million was paid to the Company.

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              The limited partnership agreement of Summit Holdings also provides that substantially all expenses incurred by or attributable to the Company, but excluding obligations incurred under the tax receivable agreement by the Company, income tax expenses of the Company and payments on indebtedness incurred by the Company, will be borne by Summit Holdings.

              The Company as the general partner may (i) at any time, require all holders of LP Units, other than holders who are current employees or service providers, to exchange their units for shares of our common stock or (ii) with the consent of partners in Summit Holdings whose vested interests exceed 66 2/3% of the aggregate vested interests in Summit Holdings, require all holders of interests in Summit Holdings to transfer their interests, provided that the prior written consent of each holder that is an affiliate of Blackstone affected by any such proposed transfer will be required. These provisions are designed to ensure that the general partner can, in the context of a sale of the Company, sell Summit Holdings as a wholly-owned entity subject to the approval of the holders thereof, including specific approval by any Blackstone affiliates then holding such units. For so long as affiliates of Blackstone collectively owned at least 5% of the outstanding LP Units, the consent of each Blackstone holder was required to amend the limited partnership agreement.

              We have entered into indemnification agreements with our directors and executive officers. These agreements require us to indemnify these individuals to the fullest extent permitted by Delaware law against liabilities that may arise by reason of their service to us, and to advance expenses incurred as a result of any proceeding against them as to which they could be indemnified. Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors or executive officers, we have been informed that in the opinion of the SEC such indemnification is against public policy and is therefore unenforceable.

              There is currently no pending material litigation or proceeding involving any of our directors, officers or employees for which indemnification is sought.

              In connection with the modification of the capital structure of Summit Holdings at the time of our IPO, we issued warrants to purchase an aggregate of 160,333 shares of Class A Common Stock to limited partners of Summit Holdings who held Class C limited partnership interests of Summit Holdings. Holders of the Class C limited partnership interests include Thomas W. Hill, a limited liability company controlled by Ted A. Gardner, and Michael J. Brady, who received warrants to purchase 29,463, 27,408, and 6,852 shares of Class A Common Stock, respectively. The warrants were issued in substitution for part of the economic benefit of the Class C interests that was not reflected in the conversion of the Class C interests to LP Units. The exercise price of the warrants is equal to the IPO price of $18.00 per share. The warrants became exercisable from and after March 17, 2016 and will expire on March 11, 2025.

              Thomas A. Beck, the President of our Cement Division, through the Thomas A. Beck Family, LLC (the "Beck LLC"), is a party to a Contribution and Purchase Agreement, dated December 18, 2014 that we entered into with the Former CCC Minority Holders (the "Contribution and

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Purchase Agreement"). In connection with the Contribution and Purchase Agreement, on March 17, 2015, Summit Holdings issued to the Former CCC Minority Holders $15.0 million in aggregate principal amount of non-interest bearing notes payable over six years. The pro rata share of the $15.0 million in notes that is due to the Beck LLC is $208,344, payable in six equal annual installments of $34,724 on each anniversary of March 17, 2015. During 2017, the second installment on the notes was paid to the Beck LLC. In addition, during 2017, tax distributions to the Beck LLC in connection with Mr. Beck's interest in the Contribution and Purchase Agreement totaled $12,160.

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SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

              To our knowledge, based solely on a review of the copies of such reports furnished to us and written representations that no other reports were required, we believe that during the fiscal year ended December 30, 2017, our officers, directors, and greater-than-10% stockholders timely filed all reports required by Section 16(a) of the Exchange Act, with the exception of (i) one Form 4 that was inadvertently not filed to report the award of restricted stock units to Joseph S. Cantie on February 28, 2017, which award was subsequently disclosed on a Form 5 filed on February 8, 2018, (ii) one Form 4 that was inadvertently not filed to report the award of restricted stock units to Steven H. Wunning on February 28, 2017, which award was subsequently disclosed on a Form 5 filed on February 8, 2018, and (iii) Form 4/As filed on March 28, 2017 that corrected the Form 4s timely filed on March 2, 2017 that inadvertently misstated the number of stock options granted to Thomas W. Hill, Thomas A. Beck, Anne Lee Benedict, Michael J. Brady, M. Shane Evans, Brian J. Harris, Damian J. Murphy, and Douglas C. Rauh.

EXPENSES OF SOLICITATION

              The accompanying proxy is solicited by and on behalf of the Board, and the cost of such solicitation will be borne by the Company. Solicitations may be made by mail, personal interview, telephone, and electronic communications by directors, officers, and other Company employees without additional compensation. We have hired Okapi Partners LLC to assist in the solicitation of proxies, who will receive a fee of $15,000, plus reasonable out-of-pocket costs and expenses, for its services. Broadridge will distribute proxy materials to banks, brokers, and other nominees for forwarding to beneficial owners and will request brokerage houses and other custodians, nominees, and fiduciaries to forward soliciting material to the beneficial owners of the common stock held on the record date by such persons. We will reimburse brokerage houses and other custodians, nominees and fiduciaries for their expenses in forwarding solicitation materials.

OTHER MATTERS

              As of the date of this Proxy Statement there are no other matters that we intend to present, or have reason to believe others will present, at the Annual Meeting. If, however, other matters properly come before the Annual Meeting, the accompanying proxy authorizes the persons named as proxies or their substitutes to vote on such matters as they determine appropriate.

PROPOSALS OF STOCKHOLDERS

              Proposals of stockholders to be considered for inclusion in the proxy statement and proxy card for the 2019 Annual Meeting pursuant to Rule 14a-8 under the Exchange Act must be submitted in writing to the Chief Legal Officer & Secretary of Summit Materials, Inc., at Summit Materials, Inc., 1550 Wynkoop Street, 3rd Floor, Denver, Colorado 80202, and must be received no later than November 30, 2018. The submission of a stockholder proposal does not guarantee that it will be included in our proxy statement.

              In addition, our Bylaws include advance notice provisions that require stockholders wishing to bring nominations for directors or other business before an annual meeting to provide proper notice in accordance with the terms of the advance notice provisions. The Bylaws' advance notice provisions do not apply if the stockholder only seeks to include such matters in the proxy statement pursuant to Rule 14a-8.

              The Bylaws' advance notice provisions require that, among other things, stockholders give timely written notice to the Secretary of the Company regarding such nominations or other business and provide

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the information and satisfy the other requirements set forth in the Bylaws. To be timely, a stockholder who intends to present nominations or a proposal at the 2019 Annual Meeting of Stockholders other than pursuant to Rule 14a-8 must provide the information set forth in the Bylaws to the Secretary of the Company no earlier than January 17, 2019 and no later than February 16, 2019. However, if we hold the 2019 Annual Meeting of Stockholders more than 30 days before, or more than 70 days after, the anniversary of the 2018 Annual Meeting date, then the information must be received no earlier than the 120th day prior to the 2019 Annual Meeting date, and not later than the close of business on the later of (i) the 90th day prior to the 2019 Annual Meeting date or (ii) the tenth day after public announcement of the 2019 Annual Meeting date. If a stockholder fails to meet these deadlines and fails to satisfy the requirements of Rule 14a-4 under the Exchange Act, we may exercise discretionary voting authority under proxies we solicit to vote on any such proposal as we determine appropriate.

              We reserve the right to reject, rule out of order, or take other appropriate action with respect to any nomination or proposal that does not comply with these and other applicable requirements.

HOUSEHOLDING: AVAILABILITY OF ANNUAL REPORT ON FORM 10-K
AND PROXY STATEMENT

              A copy of the 2017 Annual Report accompanies this Proxy Statement. If you and others who share your mailing address own common stock in street name, meaning through a bank, brokerage firm, or other nominee, you may have received a notice that your household will receive only one Annual Report and Proxy Statement, or Notice of Internet Availability of Proxy Materials, as applicable, from the Company. This practice, known as "householding," is designed to reduce the volume of duplicate information and reduce printing and postage costs. Unless you responded that you did not want to participate in householding, you were deemed to have consented to it, and a single copy of this Proxy Statement and the 2017 Annual Report (and/or a single copy of our Notice of Internet Availability of Proxy Materials) has been sent to your address. Each street name stockholder receiving this Proxy Statement by mail will continue to receive a separate voting instruction form.

              If you would like to revoke your consent to householding and in the future receive your own set of proxy materials (or your own Notice of Internet Availability of Proxy Materials, as applicable), or if your household is currently receiving multiple copies of the same items and you would like in the future to receive only a single copy at your address, please contact Householding Department by mail at 51 Mercedes Way, Edgewood, New York 11717, or by calling 1-866-540-7095, and indicate your name, the name of each of your brokerage firms or banks where your shares are held, and your account numbers. The revocation of a consent to householding will be effective 30 days following its receipt. You will also have an opportunity to opt in or opt out of householding by contacting your bank or broker.

              If you would like an additional copy of the 2017 Annual Report, this Proxy Statement, or the Notice of Internet Availability of Proxy Materials, these documents are available in digital form for download or review by visiting "Annual Reports and Proxies" at www.proxyvote.com. Alternatively, we will promptly send a copy of these documents to you without charge upon request by mail to 51 Mercedes Way, Edgewood, New York 11717, or by calling 1-800-690-6903. Please note, however, that if you did not receive a printed copy of our proxy materials and you wish to receive a paper proxy card or voting instruction form or other proxy materials for the purposes of the Annual Meeting, you should follow the instructions included in your Notice of Internet Availability of Proxy Materials.

              If you own shares in street name, you can also register to receive all future stockholder communications electronically, instead of in print. This means that links to the annual report, proxy statement, and other correspondence will be delivered to you via e-mail. Holders in street name can register for electronic delivery directly with their bank, brokerage firm, or other nominee. Electronic delivery of stockholder communications helps save the Company money by reducing printing and postage costs.

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Table of Contents

ANNEX A

RECONCILIATION OF NON-GAAP MEASURE TO GAAP

              The table below reconciles our net income to Adjusted EBITDA for the year ended December 30, 2017 and December 31, 2016.

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