Holes in Blocking Used in Engineered Wood Construction

When working with I-joists and APA rim board blocking in residential construction, knowing the proper sizing and placement of holes is critical for maintaining structural integrity while accommodating necessary penetrations for mechanical systems and ventilation.

This technical guide addresses a common question in engineered wood construction: how large can holes be in blocking members used for lateral restraint of floor and roof joists without compromising their performance?

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

The publication provides clear, practical guidelines distinguishing between lateral-restraint-only blocking applications and load-bearing blocking scenarios. It includes specific maximum allowable hole sizes based on blocking depth, detailed installation requirements, and important limitations to ensure proper field implementation. A helpful reference table and detailed diagram illustrate proper hole placement for ventilation applications.

Key sections include:

• Blocking for lateral restraint only

• Maximum allowable hole size for lateral-restraint-only blocking member

• Blocking member for load-bearing applications

Published by APA — The Engineered Wood Association.