I-Joist Fire Assembly with Gypsum Board at Bottom Flange

This detail shows 1/2" gypsum board or 5/8" wood structural panel installed at the bottom flange of an I-joist floor assembly for fire protection per IRC Section R702.3 in 2D CAD format. Developed by APA – The Engineered Wood Association, this detail is drawn from APA publication APA System Report 405: Fire Protection of Floors Constructed with Prefabricated Wood I-Joists, Form SR-405 and reflects decades of engineered wood research, testing and field-proven best practices.

This 2D detail is designed for architects, engineers, contractors and building professionals and provides clear, code-compliant guidance.

Available in multiple formats including DWG (AutoCAD), RVT (Revit), and PDF, this detail helps building professionals streamline the design and construction process while ensuring structural integrity and proper installation of engineered wood products.

Published by APA — The Engineered Wood Association.