#1ELEVATE SUMMIT MATERIALS Summit Materials to Combine with Argos USA Creating a Materials-Led Enterprise with National Scale September 7, 2023 SUMMIT Materials#2#3#4#5Attractive Financial Benefits Expected Significant Synergy Opportunity Attractive Transaction Value Accretive to Financial Metrics Well Capitalized Balance Sheet ● ● ● ● ● +$100MM p.a. of operational synergies Significant synergy realization within two years ~10x 2023E EBITDA multiple; less than 8x synergized ROIC from transaction > WACC by year three 15-25% free cash flow per share accretion expected Accretive to EBITDA growth rates with double-digit growth going forward Closing net leverage ≤3x combined EBITDA (before synergies) Significant combined free cash flow to drive deleveraging SUMMIT Materials#6Transaction Overview Summit Materials to combine with Argos USA in $3.2B transaction Consideration to Cementos Argos of $1.2B in cash and ~54.7M shares of Summit stock Cementos Argos to own ~31% of combined company Anne Noonan to serve as CEO of combined company Board will comprise 8 Summit-appointed representatives and 3 representatives appointed by Cementos Argos SUMMIT Materials CHEM#7#8#9#10#11#12#13#14#15#16#17#18#19#20#21#22#23