Exhibit 99.1 Press Release dated April 22, 2024 SIMPSON MANUFACTURING CO., INC. ANNOUNCES 2024 FIRST QUARTER FINANCIAL RESULTS Pleasanton, CA – April 22, 2024 l Net sales of $530.6 million l Income from operations of$96.1 million l Net income per diluted share of $1.77 Simpson Manufacturing Co., Inc. (the “Company”) (NYSE: SSD), an industry leader in engineered structural connectors and building solutions, today announced its financial results for the first quarter of 2024. Refer to the “Segment and Produc ...