Summit Materials, Inc. (NYSE: SUM, “Summit”) announced today the launch of an offering of 10,000,000 shares of its Class A common stock. Summit expects to grant the underwriters a 30-day option to purchase up to an additional 1,500,000 shares of Class A common stock.

Summit intends to use all of the net proceeds from the offering to purchase 10,000,000 newly-issued limited partnership units, or LP Units, from Summit Materials Holdings L.P. (“Summit Holdings”), its direct subsidiary. Summit Holdings intends to use the proceeds it receives to acquire two materials-based companies for a combined purchase price of approximately $110 million in cash, with remaining net proceeds to be used for general corporate purposes, which may include, but are not limited to, funding acquisitions, repaying indebtedness, capital expenditures and funding working capital.

Goldman, Sachs & Co. and Citigroup are serving as joint book-running managers for the offering.

The offering of these securities is being made pursuant to an effective shelf registration statement. The offering will be made only by means of a prospectus. A copy of the prospectus relating to these securities may be obtained, when available, from: Goldman, Sachs & Co., Prospectus Department, 200 West Street, New York, NY 10282, telephone: 1-866-471-2526, facsimile: 212-902-9316 or by emailing prospectus-ny@ny.email.gs.com; Citigroup, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, telephone: 800-831-9146.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Summit Materials

Summit Materials is a leading vertically integrated materials-based company that supplies aggregates, cement, ready-mix concrete and asphalt in the United States and British Columbia, Canada. Summit is a geographically diverse, materials-based business of scale that offers customers a single-source provider of construction materials and related downstream products in the public infrastructure, residential and nonresidential, and end markets. Summit has a strong track record of successful acquisitions since its founding and continues to pursue growth opportunities in new and existing markets.

Forward-Looking Statements and Information:

This press release contains “forward-looking statements” within the meaning of the federal securities laws, which involve risks and uncertainties. Forward-looking statements include all statements that do not relate solely to historical or current facts, and you can identify forward-looking statements because they contain words such as “believes,” “expects,” “may,” “will,” “should,” “seeks,” “intends,” “trends,” “plans,” “estimates,” “projects” or “anticipates” or similar expressions that concern our strategy, plans, expectations or intentions. Any and all statements made relating to the expectations for our anticipated benefits from recent acquisitions, the macroeconomic outlook for our markets, potential acquisition activity, our estimated and projected earnings, margins, costs, expenditures, cash flows, sales volumes and financial results are forward-looking statements. These forward-looking statements are subject to risks and uncertainties that may change at any time, and, therefore, our actual results may differ materially from those expected. We derive many of our forward-looking statements from our operating budgets and forecasts, which are based upon many detailed assumptions. While we believe that our assumptions are reasonable, it is very difficult to predict the impact of known factors, and, of course, it is impossible to anticipate all factors that could affect our actual results.

In light of the significant uncertainties inherent in the forward-looking statements included herein, the inclusion of such information should not be regarded as a representation by us or any other person that the results or conditions described in such statements or our objectives and plans will be achieved. Important factors could affect our results and could cause results to differ materially from those expressed in our forward-looking statements, including but not limited to the factors discussed in the section entitled “Risk Factors” in our annual report on Form 10-K for the fiscal year ended January 2, 2016. Such factors may be updated from time to time in our periodic filings with the SEC, which are accessible on the SEC’s website at www.sec.gov.

We undertake no obligation to publicly update or revise any forward-looking statement as a result of new information, future events or otherwise, except as otherwise required by law.