Messages and Online Forum Q&A

Re: OSB Sheathing

From: smetmoni@aol.com
Category: Roofing
Remote Name: 4.79.1.1
Date: 05 Oct 2005
Time: 10:12 AM

Comments

Question: Is it ok to install 7/16" OSB sheathing vertically on a shed that has 2x6 rafters spaced on 24" centers?

Builders Websource® Answer: Your question could be interpreted a few different ways, so we'll cover all the cases. You state that you're using 2x6 rafters. Do you mean studs? In any case, if  you're installing the OSB as a roofing deck, you should always install the long side horizontally across the rafters, with a minimum of two intermediate supports. Stagger successive rows and leave approximately 1/8" on all sides for swelling (about the diameter of a nail). Also, for a roof application, use at least 1/2" or thicker. 5/8" or thicker is preferred over a 24" rafter span to help prevent sagging.

On vertical wall surfaces, you may install the OSB sheathing horizontally or vertically. Depending on the height of the wall, if your studs are spaced on 24" centers, install solid horizontal blocking at the seams where two panels butt up against each other. Furthermore, if you install OSB vertically and plan to use stucco, don't use 7/16" OSB. Rather, use 19/32" OSB with a span rating of 20/40. This will provide a more rigid substrate for the stucco and help to minimize flexing.  As with the roof, it's a good idea to stagger the panels vertically, unless the length of the panels goes the full height from the sill plate to the top plate, in which case there is no need to stagger the panels. Be sure to follow the proper nailing schedule, which may be more stringent in areas subject to earthquakes and/or high winds. For additional technical information on the application of OSB and other structural panels, visit the ENGINEERED WOOD ASSOCIATION online.

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