Designing Diaphragms Over Existing Board Floors or Roofs

When retrofitting an existing structure or designing new construction that requires maintaining the aesthetic of exposed wood boards, designers face the challenge of adding diaphragm resistance while preserving or working around existing board decking.

This publication is designed for: designers, engineers

This publication provides design considerations for installing wood structural panel diaphragms over existing board floors or roofs. It addresses common oversights in retrofit design and provides practical guidance on field nailing schedules, faster penetration depths and load path continuity.

Key sections include:

• Assessing existing deck condition and suitability as a substrate

• Ensuring proper anchorage to prevent out-of-plate buckling

• Meeting minimum nail penetration requirements for shear capacity

• Maintaining continuous shear transfer between panel edges

• Properly transferring loads at diaphragm perimeters and chord connections

Published by APA — The Engineered Wood Association.