#1Investor Presentation August 2017 75X45 SUMMIT Materials#2Legal Disclaimer Forward-Looking Statements This presentation 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 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 filed with the SEC on February 28, 2017. 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. Non-GAAP Financial Measures Included in this presentation are certain non-GAAP financial measures, such as Adjusted EBITDA, Further Adjusted EBITDA, Adjusted Net Income (Loss), Adjusted Earnings Per Share, Adjusted Cash Gross Profit, Adjusted Cash Gross Profit Margin, Net Debt, Net Leverage and Free Cash Flow designed to complement the financial information presented in accordance with U.S. GAAP because management believes such measures are useful to investors. These non- GAAP financial measures should be considered only as supplemental to, and not superior to, financial measures provided in accordance with GAAP. Please refer to the appendix of this presentation for a reconciliation of the historical non-GAAP financial measures included in this presentation to the most directly comparable financial measures prepared in accordance with GAAP. Reconciliations of the non-GAAP measures used in this presentation are included or described in the tables attached to the appendix. Because GAAP financial measures on a forward-looking basis are not accessible, and reconciling information is not available without unreasonable effort, we have not provided reconciliations for forward-looking non-GAAP measures. 1 SUMMIT Materials#3SECTION ONE Corporate Overview 2 SUMMIT Materials#4Summit Materials Overview Pure-Play, Our Value Proposition Materials-based positions in well-structured, early-cycle markets Integrated supplier of construction materials (aggregates, cement), products (ready-mix concrete, asphalt) and paving services Favorable long-term industry dynamics within private and public end-markets 2/3 of net revenue = early cycle residential/non-residential end markets; 1/3 of net revenue = state public infrastructure spending Exceptional record of financial growth and operational execution Since IPO (2015), generated significant growth in net revenue, adjusted EBITDA, net income, all while reducing net leverage Unique acquisition strategy with proven integration experience Invested $2.6 billion in 57 acquisitions since 2009; focused on acquiring/integrating/improving assets in well-structured markets - - Vertically-Integrated Heavy Materials Business - Proven management team with decades of industry experience Founded by Tom Hill (current CEO) and former CEO of Old Castle Materials Leading Positions In Early-Cycle Markets 3 Top 5 Market By Net Revenue (2016) Market Exposure 21 STATES + VANCOUVER, B.C. Geographically diverse portfolio 12 PLATFORM COMPANIES Completed 57 acquisitions since 2009 TOP 5 STATES By net revenue: TX, UT, KS, MO, VA SUMMIT Materials#5Decentralized, Materials-Based Model Local Leadership, Diversified End-Markets SUM is #1 market player across 50% of the platform markets served Estimated market share by platform BOXLEY CON AGG HAMM Mainland Sand & Gravelt ZA JANEDE TE PAKARTOTE CLEVEme weng ALLEYTON FK HALL CONSTRUCTION, LTD Cornyo & Sons Troy Vines, Inc. CONTINENTAL CEMENT Hinkle KILGORE COMPANIES West-Central, Virginia Columbia, Missouri Northeast Kansas Vancouver, B.C. West Houston Texas Northern Texas Wichita, Kansas Midland/Odessa, Texas Mississippi River Corridor Central, Kentucky Austin, Texas Sal Lake City, Utah Diversified Exposure Across Lines of Business, End-Market and Geography Adjusted EBITDA By Line of Business (FY16) Services 6% Products 33% Top 3 position Top 3 position Top 3 position Top 3 position Materials 61% Net Revenue By End-Market (FY16) Public 37% 4 Private 63% Top 2 position Top 2 position #1 position #1 position #1 position #1 position #1 position #1 position Net Revenue By Geography (FY16) All Other States 32% "Top 5" States 68% SUMMIT Materials#6Key Financial Metrics Y/Y Growth In Net Revenue, Operating and Net Income Net Revenue ($MM) $412.6 (1) 2Q16 $478.4 2Q17 $13.4 $1,406.5 Reported Net Income Attributable to Summit, Inc. ($MM) 2Q16 LTM 2Q16 LTM 2Q17 $50.0 $1,605.0 +274% y/y 2Q17 Operating Margin defined as Operating Income divided by Net Revenue 5 Operating Income ($MM) & Margin (%) (1) 11.4% $46.9 2Q16 Basic Earnings Per Share $0.21 2Q16 17.2% $82.4 2Q17 $0.47 +124% yly 2Q17 SUMMIT Materials#7Key Financial Metrics (Non-GAAP) Strong Cash Generation, Margin Expansion, Income Growth Adjusted Cash Gross Profit ($MM) & Margin (%) (1.2) ୧୯୭ 38.8% $160.1 (3) 2Q16 39.3% $188.2 Adjusted Diluted Net Income ($MM) (1) 2Q17 $46.2 35.7% $502.3 37.2% $597.4 LTM 2Q16 LTM 2Q17 $53.6 +16% yly 2Q16 2Q17 See appendix for reconciliation of these non-GAAP metrics to the most comparable GAAP metrics Adjusted Cash Gross Profit Margin defined as Adjusted Cash Gross Profit divided by Net Revenue Adjusted EBITDA margin defined as Adjusted EBITDA divided by Net Revenue Adjusted diluted share count includes all outstanding Class A common stock and LP Units 6 Adjusted EBITDA ($MM) & Margin (%) (1.3) 27.8% $114.7 2Q16 28.3% $135.2 2Q17 $0.45 23.7% $333.9 Adjusted Diluted Earnings Per Share (1,4) 2Q16 $397.1 LTM 2Q16 LTM 2Q17 $0.48 24.7% +7% yly 2Q17 SUMMIT Materials#8Price and Volume Analysis Broad-Based Y/Y Recovery In Organic Sales Volumes Average Selling Price, Excluding Acquisitions (y/y % change) 6.7% Aggregates -1.7% Sales Volume, Excluding Acquisitions (y/y % change) Aggregates 6.1% -9.7% Cement Cement Ready-Mix Concrete 9.2% 7.1% -5.4% 3.0% Asphalt 3.6% -19.2% 2Q16 7 Average Selling Price, Including Acquisitions (y/y % change) 9.5% Aggregates 16.6% 10.9% 2Q17 -0.5% Sales Volume, Including Acquisitions (y/y % change) Aggregates Cement 114.7% 10.7% 8.3% Cement Ready-Mix Concrete 29.8% 9.4% 2.9% Asphalt 15.3% 1.1% SUMMIT Materials#9Adjusted Cash Gross Margin Scorecard LTM 2Q17 Margins Increased Across all Lines of Business Aggregates Business Adjusted Cash Gross Profit Margin (%)(1,2) 63.3% IN 2Q16 26.9% 68.3% 2Q16 2Q17 Products Business Adjusted Cash Gross Profit Margin (%)(1,2) 25.6% 60.5% 2Q17 LTM 2Q16 LTM 2Q17 62.9% 25.6% 25.8% LTM 2Q16 LTM 2Q17 Cement Segment Adjusted Cash Gross Profit Margin (%)(1,2) 57.4% 8 52.2% 2Q16 26.5% 2Q17 2Q16 Services Business Adjusted Cash Gross Profit Margin (%)(1,2) 27.7% 2Q17 43.7% LTM 2Q16 LTM 2Q17 See reconciliations of Adjusted Cash Gross Profit Margin in the appendix Adjusted Cash Gross Profit Margin is defined as Adjusted Cash Gross Profit divided by Net Revenue. In this presentation of the data, Adjusted Cash Gross Profit is calculated by line of business, less net cost of revenue by line of business 46.0% 26.3% 29.5% LTM 2Q16 LTM 2Q17 SUMMIT Materials#10Consistent Margin Expansion Since IPO Adjusted EBITDA Margin of 28.3% in 2Q17 Adjusted EBITDA Margin +450 bps Since 2Q15(1,2) (Y/Y % Change) ~ 23.8% 2Q15 Adjusted EBITDA margin defined as Adjusted EBITDA divided by net revenue See reconciliation of Adjusted EBITDA to Net Income in the Appendix 27.8% 2Q16 9 28.3% 2Q17 SUMMIT Materials#11Robust Incremental Margins Adjusted Cash Gross Profit Incremental Margins by LOB Seeing Sustained Strength In Cement and Aggregates Incremental Margins (1) (1) 53.1% 2Q16 59.2% 147.2% 2Q17 100.4% Cement Aggregates 47.9% 10 84.4% LTM 2Q16 Incremental Adjusted Cash Gross Profit Margin defined as LTM y/y change in Adjusted Cash Gross Profit divided by the LTM y/y change in Net Revenue 62.8% 75.9% LTM 2Q17 SUMMIT Materials