Deflection Limits in the 2018 IBC for Engineered Wood Products

This publication clarifies a frequently misunderstood provision in the 2018 International Building Code (IBC) regarding the calculation of combined dead and live load deflections for engineered wood structural members.

This publication is designed for: engineers, designers, architects

This publication explains the intent behind IBC Table 1604.3 footnote d, which specifies that deflection limits apply to creep deflection plus live load deflection – not immediate dead load deflection.

Key sections include:

• Guidance on properly estimating creep components for different engineered wood products and service conditions

• Explanation of when the common engineering practice of using immediate dead plus live load deflection is appropriate

• Application of time-dependent deformation factors from the National Design Specification for Wood Construction

Published by APA — The Engineered Wood Association.