Exhibit 99.1 Summit Materials, Inc. Reports Third Quarter 2024 Results Pricing Momentum Continues Sets ELEVATE Summit Record for Quality of Earnings Refining 2024 Guidance DENVER, CO. - (October 30, 2024) - Summit Materials, Inc. (NYSE: SUM) ("Summit," "Summit Materials," "Summit Inc." or the "Company"), a market-leading producer of aggregates and cement company, today announced results for the third quarter ended September 28, 2024. All comparisons are versus the quarter ended September 30, 2023 unless not ...