Summit Materials, Inc. announced the appointment of Jorge Mario Velasquez, Irene Moshouris, and Juan Esteban Calle to the Summit Materials Board of Directors, effective January 12, 2024. Following these appointments, and together with the retirement of John Murphy, the Board consists of 11 directors, 10 of whom are independent. Jorge Mario Velasquez has served as president of Grupo Argos, an infrastructure holding company in the Americas since 2016.

Grupo Argos is a leader in the cement business through its subsidiary Cementos Argos, which, together with affiliates, is a 31% owner of Summit Materials. Mr. Velasquez began his career at Argos in 1983 and has held positions of increasing responsibility within the organization including an outstanding career as president of Cementos Argos, leading their business across 15 countries. He is currently a senior member of the board of directors of Cementos Argos, Celsia, Odinsa, Fundación Grupo Argos, Proantioquia, and the Superior Council of the EIA University.

Mr. Velasquez will serve on the Company's Governance and Sustainability Committee. Irene Moshouris was with United Rentals, Inc. for 17 years, most recently as senior vice president and treasurer, before retiring in 2023. During her distinguished tenure, Ms. Moshouris played a key executive role helping to complete approximately 25 acquisitions that transformed the company into a leading mega-cap industrials entity.

Prior to United Rentals, she served in finance management roles with Avon Products and GTE Corp.Ms. Moshouris has a bachelor's degree in accounting and economics from Queens College, a Master of Laws degree in tax law and taxation from New York University School of Law, and a juris doctor degree from Brooklyn Law School. Ms. Moshouris will serve on the Company's Audit Committee. Juan Esteban Calle, CEO of Cementos Argos S. A for the prior 8 years was instrumental to the combination between Summit and Argos USA.

Prior to his current role, Mr. Calle served as the General Manager of the multi-utility company EPM of Medellín, leading the successful transformation of Grupo EPM, and implementing a growth strategy in both local and international markets. With a background as a Senior Investment Banking Associate at Chase Manhattan Bank in New York, founding partner of Metrix Finanzas in Bogota, Secretary of the Treasury of the Department of Antioquia, Director of Foreign Investment at the ProColombia Office in Canada, and an Investment Advisor at the Bank of Montreal, Mr. Calle's career reflects a strategic vision and leadership across various sectors, showcasing his financial acumen and international expertise. He holds a degree in Business from EAFIT University, and an MBA with a focus on Finance and Economics from the University of Chicago Booth School of Business.

Mr. Calle Restrepo will serve on the Company's Human Capital and Compensation Committee.