Summit Materials, Inc. (NYSE: SUM, "Summit") announced today that certain selling stockholders, including affiliates of The Blackstone Group L.P., have commenced a secondary offering of 16,614,949 shares of Class A common stock. Summit is not offering any shares of Class A common stock in the offering and will not receive any proceeds from the sale of shares in this offering. Barclays Capital Inc. is serving as sole book-running manager 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: Barclays Capital Inc. by telephone at 1 (888) 603-5847 or by email at Barclaysprospectus@broadridge.com. 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.