Balcony Design for I-Joist Floor with Lumber Cantilever

Following the tragic 2015 balcony collapse in Northern California that resulted in six fatalities, building codes underwent significant revisions to address critical safety and durability concerns in exterior balcony construction. This technical publication provides essential guidance on designing balconies with lumber cantilevers attached to I-joist floor systems, incorporating updated code requirements and best practices for moisture protection and structural integrity.

This publication is designed for: engineers, architects, designers, builders, contractors

This document supplements Figure 4 of APA Design and Construction Guide: Performance Rated I-Joists, Form Z725, with detailed specifications for compliant balcony design. It addresses 2021 International Building Code requirements for preservative-treated or naturally durable wood, moisture barrier systems, ventilation requirements, and inspection protocols. The publication includes engineering calculations based on 60 psf live loads and incorporates ASCE 7-16 handrail loading requirements.

Key sections include:

• Code Requirements for moisture protection and ventilation

• Recommended Lumber Cantilever Design specifications

• Detailed construction diagrams with fastening schedules

• Lumber grade selection tables for various species

• Load calculation assumptions and design criteria

Published by APA — The Engineered Wood Association.