Summit Materials : Annual Report 2020 and Proxy Statement

NOTICE OF 2021 ANNUAL MEETING OF 2020STOCKHOLDERS, PROXY STATEMENT, AND

ANNUAL REPORT

LOCAL PRESENCE.

NATIONAL SCALE. BUILDING MORE TOGETHER.

LETTER FROM

THE CHAIRMAN

Howard Lance

Chairman of the Board of Directors Summit Materials, Inc.

To Our Valued Stakeholders:

On behalf of the Board of Directors, and all the Summit Materials employees, I want to thank those on the frontlines of the COVID-19 pandemic who have worked to keep all of us safe. We also offer our sympathies to those who have personally experienced loss during this time.

Despite the challenges 2020 presented, it was an exceptional year for our Company. Summit produces the essential materials that support the comforts of life, including by supplying industries like residential construction, energy production and transportation infrastructure.

Our role was proven more important than ever in 2020 as we achieved record Adjusted EBITDA and cash flows, allowing us to reduce our debt ratio to the lowest it has ever been.

In 2020 we welcomed our new CEO, Anne Noonan. Anne has been working tirelessly since her first days and we are particularly excited about her leadership in establishing the Elevate Summit strategy presented to investors on March 16, 2021. Elevate Summit is a comprehensive program designed to maximize returns to our stakeholders by focusing on key financial goals: achieving greater than 30% Adjusted EBITDA Margin, greater than 10% Return on Invested Capital (ROIC), and a leverage ratio of less than three times. Guiding these ambitious, multi-year objectives are our mission, vision and values that are described in this Annual Report. Our vision is to be the most socially responsible, integrated construction materials solutions provider collaborating with stakeholders, to deliver differentiated innovations and solve our customers' challenges.

As part of our commitment to social responsibility we continue to advance and improve sustainability programs across the Company. We also continue to provide deeper levels of transparency and accountability to our stakeholders. In 2020 we completed an extensive greenhouse gas emissions study that enables increased visibility into our impact on the environment and will allow us to plan reduction efforts in the coming years - we are wholly in support of achieving carbon neutrality by 2050.

We are also committed to improving our human capital management, with focus on the areas of safety, talent management and recruitment.

With regards to corporate governance, as we indicated last year, the Board of Directors believes that a classified board structure and supermajority voting requirements are no longer necessary, and the Company has included in this year's annual meeting agenda proposals to (i) declassify the Board of Directors, and (ii) eliminate the supermajority voting require- ment. Additionally, we are pleased to note that with Anne Noonan's appointment, Summit has now achieved gender parity on its Board.

Thank you again for your continued support of Summit Materials. We recognize and appreciate the responsibility that your commitment brings. We believe strongly in Summit Materials, the dedication of our nearly 6,000 employees, and the opportunities that lie ahead.

Sincerely,

Howard Lance, Chairman of the Board of Directors of Summit Materials, Inc.

To Our Valued Stakeholders:

This is my first letter to you as CEO of Summit Materials, and as I said upon accepting this role, it is an honor to lead this Company into its next phase of growth and value creation. We are grateful for the continued trust and support of our shareholders, customers and communities.

In 2020, the world and global economy faced unprecedented difficulties due to the COVID-19 pandemic. On behalf of Summit Materials, I want to thank all the frontline workers who have labored so hard to keep us safe. I also want to thank all of Summit's employees, as essential workers, you have persevered in the face of great adversity to continue to provide the infrastructure that is vital to the communities we serve. Finally, to all those who have struggled or have lost loved ones over the course of the pandemic, we extend our deepest sympathies.

Even during the challenging circumstances of this past year, our employees were able to not only adapt all our procedures to address COVID but better our safety record. From 2019 to 2020, we improved our recordable incident rate by 6% and our lost time incident rate by 62%.

From a financial perspective, 2020 was an outstanding year for Summit. We reported net income of $138 million and Adjusted EBITDA of $485 million.1 Our aggregates businesses, particularly in the West Segment, delivered superb results, driven by robust demand in Utah and superior margin performance. We were also pleased with the strong performance generated by our ready mix, asphalt, and paving lines of business across Texas. These successes helped offset a challenging year for our Kentucky and Cement businesses. Ken- tucky was impacted by the cancellation of lettings due to funding conditions, while our Cement business was hindered by the temporary shutdown of its waste recycling business.

Throughout 2020, we committed to increase cash flow from operations and improve our balance sheet. We reduced our leverage ratio from 3.6x to 3.2x Net Debt to EBITDA,1 which is the lowest in Company history. We also increased our ROIC, from 7.5% in 2019 to 8.1% in 2020.1

LETTER FROM

THE CEO

Anne P. Noonan

Chief Executive Officer

Summit Materials, Inc.

Summit's team spent the last few months developing our strategy for the future, in careful con-

sideration of feedback from investors and other stakeholders. I want to thank each investor who participated in our perception study as well as our customers, who also gave us great insight.

During this process we defined Summit's Mission, Vision, and Values which are set forth in the pages that follow and will guide our decisions moving forward, including our new strategic roadmap. We call this new initiative Elevate Summit, and it includes four core strategic priorities:

• Market Leadership: Where we are dedicated to being the leader in exurban and rural markets to enhance our long-term value to customers and stakeholders
• Asset Light Approach: Where we will focus on developing strategic partnerships to do more business with less invested capital
• Social Responsibility: Where we are committed to improving our social and human impact, land reclamation practices, and carbon emissions
• Innovation: Where we will focus on enhancing our value proposition to customers by leveraging technology, anticipating their current and future needs, and delivering customized solutions when and how they want them.

Execution of our strategic priorities will be enabled by a culture of excellence, simplification, and standardization. We've set ambitious, yet achievable goals by which we'll measure success, which include driving towards an Adjusted EBITDA margin of greater than 30%; a ROIC of greater than 10%, and less than three times Net Debt to EBITDA. Investor feedback suggests that achievement of these goals will further enhance alignment with shareholders.

I want to close by again thanking our nearly 6,000 employees whose hard work is the reason for our performance in 2020 - your determination and dedication to the Company's success, particularly during a global pandemic, is inspiring. Finally, I want to thank our Board of Directors for their continued counsel and all of our stakeholders, including our investors and customers, for their ongoing commitment and support.

Sincerely,

Anne P. Noonan, Chief Executive Officer of Summit Materials, Inc.

(1) This is a non-GAAP measure, please see the reconciliations at the back of this report.

FINANCIAL DATA

NET INCOME ATTRIBUTABLE

TO SUMMIT, INC .

	150		$138 MILLION
$ IN MILLIONS	120
90
60	$59.1 MILLION
	$33.9 MILLION
	30
	0
	2018	2019	2020

	A D J U S T E D
	EBITDA MARGIN 1
	25%	22.7%	22.7%
	21.3%
	20%
(%)
MARGIN	15%
10%
	5%
	0%
	2018	2019	2020

2018		4.5x

YEAR - END	2019							3.6x
NET LEVERAGE 1
	2020						3.2x
	0	1	2	3	4	5

NET REVENUE

	$2.5
			$2.03 B	$2.13 B
	$2.0	$1.91 B
$ IN BILLIONS	$1.5
$1.0
	$0.5
	$0
		2018	2019	2020

FINANCIAL DATA SUMMARY

In 2020, our net revenue increased 5.1% over 2019, and we reported earnings of $138.0 million, or $1.21 per basic share. Additionally, operating income increased 5.4% to $225.2 million. We achieved these results, despite challenges due to COVID, as a result of the tireless work of our nearly 6,000 employees and by focusing on sustainable growth with investments in greenfields and acquisitions aligned with end markets that are underpinned by strong growth fundamentals.

(1) This is a non-GAAP measure, please see the reconciliations at the back of this report.

ELEVATE SUMMIT IS DESIGNED TO YIELD

LONG-TERM RESULTS

>30% >10% <3x

Adjusted EBITDA	Return on Invested	Net Debt to
Margin	Capital (ROIC)	EBITDA

Summit's mission is to provide the foundation to connect our communities today and build a better tomorrow.

Summit's vision is to be the most socially responsible, integrated construction materials solution provider, collaborating with stakeholders to deliver differentiated innovations and solve our customers' challenges.

SAFETY: We are committed to keeping our employees, customers, and communities safe in all that we do.

INTEGRITY: We build trust by doing what's right and remaining accountable, even when no one is watching.

SUSTAINABILITY: We answer to the impact of our actions and seek out opportunities to develop innovative practices and solutions.

INCLUSIVITY: We act intentionally to bring together our local communities and drive equity for all stakeholders.