Simpson Manufacturing Co., Inc. and Subsidiaries Consent of Independent Certified Public Accountants Exhibit 23 We consent to the incorporation by reference in the Registration Statement on Forms S-8 (File No. 33-85662 and File No. 33-90964) of Simpson Manufacturing Co., Inc. of our report dated February 2, 2000, relating to the financial statements and financial statement schedule, which appears in this Form 10-K. PricewaterhouseCoopers LLP San Francisco, California March 28, 2000