Summit Materials : Investor Presentation – September 2021 Site Tour

Welcome to the Summit Jefferson Quarry Site Tour September 2021

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Cautionary Statement

Forward-Looking Statements

This presentation includes "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," "outlook," "should," "seeks," "intends," "trends," "plans," "estimates," "projects" or "anticipates" or similar expressions that concern our strategy, plans, expectations or intentions. All statements made relating to our estimated and projected earnings, margins, costs, expenditures, cash flows, growth rates and financial results are forward-looking statements. These forward-looking statements are subject to risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from future results, performance or achievements expressed or implied by such forward-looking statements. 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 effect 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 realized. 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 Summit Materials, Inc.'s ("Summit Inc.") Annual Report on Form 10-K for the fiscal year ended January 2, 2021 as filed with the Securities and Exchange Commission (the "SEC), and any factors discussed in the section entitled "Risk Factors" in any of our subsequently filed SEC filings; and the following: the impact of the coronavirus ("COVID-19") pandemic on our business, or any similar crisis; our dependence on the construction industry and the strength of the local economies in which we operate; the cyclical nature of our business; risks related to weather and seasonality; risks associated with our capital-intensive business; competition within our local markets; our ability to execute on our acquisition strategy, successfully integrate acquisitions with our existing operations and retain key employees of acquired businesses; our ability to implement and successfully execute on our Elevate Summit Strategy; our dependence on securing and permitting aggregate reserves in strategically located areas; declines in public infrastructure construction and delays or reductions in governmental funding, including the funding by transportation authorities and other state agencies particularly if such are not augmented by federal funding or if the federal government fails to act on a highway infrastructure bill; our reliance on private investment in infrastructure, which may be adversely affected by periods of economic stagnation and recession; environmental, health, safety and climate change laws or governmental requirements or policies concerning zoning and land use; costs associated with pending and future litigation; rising prices for commodities, labor and other production and delivery inputs as a result of inflation or otherwise; conditions in the credit markets; our ability to accurately estimate the overall risks, requirements or costs when we bid on or negotiate contracts that are ultimately awarded to us; material costs and losses as a result of claims that our products do not meet regulatory requirements or contractual specifications; cancellation of a significant number of contracts or our disqualification from bidding for new contracts; special hazards related to our operations that may cause personal injury or property damage not covered by insurance; unexpected factors affecting self-insurance claims and reserve estimates; our substantial current level of indebtedness, including our exposure to variable interest rate risk; our dependence on senior management and other key personnel, and our ability to retain and attract qualified personnel; supply constraints or significant price fluctuations in the electricity and petroleum-based resources that we use, including diesel and liquid asphalt; climate change and climate change legislation or other regulations; unexpected operational difficulties; interruptions in our information technology systems and infrastructure, including cybersecurity and data leakage risks; and potential labor disputes, strikes, other forms of work stoppage or other union activities. All subsequent written and oral forward-looking statements attributable to us, or persons acting on our behalf, are expressly qualified in their entirety by these cautionary statements. Any forward-looking statement that we make herein speaks only as of the date of this presentation. 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 required by law.

Non-GAAP Financial Measures

Included in this presentation are certain non-GAAP financial measures, such as Adjusted EBITDA, Adjusted EBITDA Margin, and Return on Invested Capital (ROIC), 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-lookingnon-GAAP measures. For the same reasons we are unable to address the probable significance of the unavailable information, which could be material to future results.

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Safety Requirements

All visitors are to report to the	Site Specific Hazard Training
main office to sign in	will be provided to all visitors

3 points of contact must be	Seat Belts MUST be inspected
maintained at all times when	and worn at all times if
entering or exiting vehicles or	provided on any equipment
climning stairs/ladders	while in motion

Slips, Trips, and Falls are the	The Following PPE is required
at all times in Required Areas:
#1 cause of most accidents at	Hard hat, Safety glasses, high
most mines. Be careful when	visibility clothing, hearing
walking in the mine.	protection where required, and
	safety toed boots

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What You'll See Today

• Jefferson Quarry sold 1.0Mt Aggregates in 2019/2020; SUM was a royalty holder until this year
• SUM took over lease in May 2021, invested in new plant
• It is the closest quarry along I-85 to the South Carolina state line other than Carnesville (which has reserves owned by SUM)
• Jefferson is part of the Greenfield Program in Summit's East Segment
• Its local commercial brand is Georgia Stone Products and its financial and operating results contribute to Summit's East Segment

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Company Bios

ANNE NOONAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER; DIRECTOR

Anne Noonan joined Summit in 2020 after having served as President and CEO of OMNOVA Solutions Inc., a global producer of emulsion polymers, specialty chemicals, and decorative and functional surfaces, from November 2016 through January 2020. During her tenure, she transformed the company into a high performing specialty solutions provider with 31% revenue and 22.5% EBITDA growth in high value specialty markets. Ms. Noonan joined OMNOVA in September 2014 as President of its Performance Chemicals business segment. Prior to OMNOVA, Anne spent 27 years at Chemtura Corporation, a global manufacturer of specialty chemicals. During her tenure with Chemtura, Anne held leadership roles across a wide range of disciplines, from strategic marketing to product development and innovation, to mergers and acquisitions and general management. Anne serves on the board of CF Industries, a global leader in nitrogen fertilizer manufacturing and distribution. She earned her Bachelor of Science Honors degree in chemistry and her Master of Science in organometallic chemistry from University College Dublin, Ireland.

AB BOXLEY, EXECUTIVE VICE PRESIDENT

Ab's previous positions with Summit include President, East Region, and President, Boxley Materials Company, a construction materials producer of aggregate, asphalt, block and concrete. He is a member of World President's Organization, Director, RGC Resources, Inc. (Roanoke Gas Company), Director Pinnacle Financial Partners, Inc., and Director Insteel Industries. Ab currently serves on the board of Carilion Clinic and is Chair of the Audit Committee, and Virginia Western Community College Educational Foundation. He is a Past Chair, Roanoke Valley Economic Development Partnership and Roanoke Outside Foundation, former Vice Chair GO VA Regional Council, and Board Member, Business Leadership Fund. He received his B.A. in Economics from Washington & Lee University and his M.B.A. from the University of Virginia. Mr. Boxley has been active in youth sports, coaching Baseball, Basketball and Football in Roanoke City.

BART BOYD, EAST REGION PRESIDENT

Bart is a 28-year, third generation industry professional and entrepreneur. He joined Summit Materials when his company, Georgia Stone Products was acquired in 2017. Bart started his career with Vulcan Materials Company in 1994 after graduating from Georgia Southern University. Mr. Boyd worked in various roles with VMC leading up to his role as the Vice President and General Manager where he had P&L responsibility for the 24 operating quarry sites and 14 ready mix operations in GA. Bart serves as the Chairman of the Board for Clydesdale Charitable Funding, a 501c3 organization. In addition to attending Georgia Southern University, he completed the Executive Development Program at Kellogg School of Management at Northwestern University in 2011.

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