The Horizontal vs. Vertical Sheathing Debate - Fine Homebuilding FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram Plus Icon Close Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Main Menu
Subscribe

In every issue you'll find...

  • Expert insights on techniques and principles
  • Unbiased tool reviews
  • Step-by-step details to master the job
  • Field-tested advice and know-how
Subscribe Now!
Subscribe
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
  • Join
  • Log In
Main Menu Subscribe

Fine Homebuilding Project Guides

Framing

Guide Home
Chapter
  • Introduction to Framing
  • Framing Tools, Techniques, and Materials
  • Framing Floors
  • Framing Walls
  • Framing Stairs
  • Framing Roofs
  • Efficient Framing Methods
  • Timber Framing
Ask the Experts

The Horizontal vs. Vertical Sheathing Debate

Does the direction you install plywood on a wood-framed wall affect how strong it is?

By Matthew Millham Issue 283 – June 2019
Article Image

On an episode of the Fine Homebuilding Podcast, someone said that installing structural sheathing horizontally on walls is superior to vertical installation, but APA (the Engineered Wood Association) maintains both installations are equal provided the panels are attached to framing or blocking. Can you please cite a source that explains the case for horizontal sheathing being better, or at least clarify which, if either, orientation is superior?

—Kevin Brennan via email

Associate editor Matthew Millham responds: If all we’re talking about is shear, where the load is parallel to the wall, you’re right that there’s no difference in performance between vertical sheathing and horizontal sheathing with the edges blocked. But that’s just part of the story.

Structural sheathing panels have a “strength axis” that runs parallel with the panel’s length unless marked otherwise. On roofs and floors, sheathing is installed perpendicular to supports because this is the orientation that results in the strongest roof or floor. Wind loads perpendicular to a wall are similar to floor and roof loads, and installing sheathing horizontally makes walls better at resisting wind pressure.

One place this issue shows up is in the American Wood council’s Wood Frame Construction Manual (WFCM), where there’s a table for wall-sheathing requirements for wind loads. Here, it’s clear that horizontal sheathing outperforms vertical, especially at higher wind speeds. For example, in areas categorized as Exposure B— places where obstructions, such as suburban or wooded areas, temper the wind—a 3⁄8-in.-thick panel with a span rating of 24/0 (meaning it can be used on roofs with supports up to 24 in. on center, and not as floor sheathing) can handle three-second gusts up to 195 mph when installed horizontally on studs spaced 24 in. on center. Installed vertically, the same panel can only handle gusts up to 110 mph on the same stud spacing.

The IRC, meanwhile, allows you to orient the sheathing in either direction for wind loads, but includes an important exception: If you’re using 3-ply plywood panels of any thickness on studs spaced greater than 16 in. on center, the IRC wants the panels installed with their strength axis perpendicular to supports (in other words, horizontally) to handle wind pressure. In those products, the grain of the face plies is typically oriented with the long axis of the panel (creating the strength axis), and the single alternate ply in the middle doesn’t provide enough strength for it to handle wind pressure when the panel is installed vertically. And where designing for wind is required— mainly coastal areas of the southeast where hurricanes are common—the IRC points builders to the WFCM and other resources for guidance.

Photo: Tim Furlong Jr.

From Fine Homebuilding #283

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Sign Up
X
X
Previous: Efficient Methods for Installing Wall Sheathing Next: Working With ZIP R-Sheathing

Guide

Framing

Chapter

Framing Walls

Comments are closed.

Framing

Framing

Trusted, in-depth guidance from the pros for framing a durable, code-compliant house

View Project Guide

View All Project Guides »

Become a member and get unlimited site access, including the Framing Project Guide.

Start Free Trial

Introduction to Framing
  • House Framing Concepts, Tips, and More
Framing Tools, Techniques, and Materials
  • Tools
  • Techniques
  • Framing Lumber
  • Steel
Framing Floors
  • Floor Framing
  • Engineered Floors
  • Floor Sheathing
Framing Walls
  • Wall Framing Basics
  • Layout
  • Wall Assembly
  • Raising and Straightening Walls
  • Framing Rough Openings
  • Blocking
Framing Stairs
  • Stair Layout
  • Building Stairs
Framing Roofs
  • Roof-Framing Basics
  • Roof Design
  • Laying Out and Cutting Rafters
  • Framing Valleys
  • Working with Trusses
  • Dormers
  • Special Situations
Efficient Framing Methods
  • Advanced Framing
  • Double-Stud Walls
Timber Framing
  • Timber-Frame Construction
  • Timber-Frame Design

Fine Homebuilding

Follow

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Manage Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Privacy Policy
  • Careers
  • Copyright
  • Terms of Use
  • Accessibility

© 2021 The Taunton Press, Inc. All rights reserved.

    Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Reader Projects
  • Magazine
  • Members
  • FHB House
  • Podcasts

  • FHB Podcast
  • ProTalk
  • Account

  • Log In
  • Join

    Podcasts

  • FHB Podcast
  • ProTalk
  • Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

    Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

    All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

    Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

    More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • Customer Support

    Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Follow

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 52%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in