Is it ok to sheath over plywood sheathing with another layer of OSB on a roof? This would be after tearing off the shingles..
In older homes like these, the main remodeling goal is often a more welcoming, more social, and more functional kitchen.
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Replies
Why are you going over the plywood?If it's because the plywood is rotted you need to remove the rotted plywood and replace with plywood.The OSB stuff is garbage cheapo stuff that developers use to save a buck and the stuff is hard to nail into.It doesn't have the same integrity as plywood and you cannot install the OSB on a roof.
Not sure where you are located but up here in MI OSB is used all the time for roof sheathing.
Todd - Framing Square
Not rotten.. Its 3/8 plywood..
I see no reason not too. I don't use OSB for new but in re-roof applications we have a lot of hundred year old homes with 7/8" boards for sheathing and after four roofs it can be pretty used up, with splits and knot holes gone. Framing stle being what it was on some of these old farmhouises, I fear what would happen if we took it all of so we go over the old with 7/16 OSB to smooth it out and add a little strenghth. Your doubling up situation would be similar to underlayment plus subfloor on flooring. The two plies together don't hurt.
but let me go beyond and assume something here...
Whoever built this in the first place used substandard materials to sheath with. That tells me that either they didn't have the faintest idea what they were doing or that they were cheap SOBs. Either of those scenarios makes me expect that they may well have underframed also. If those roof rafters just barely made it through life with 3/8 ply, adding the weight of OSB could be the straw that broke the camels hump...
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My office was done just like that. We had some leaks with some slight rot and delamination here and there. Also the existing ply was too thin also. It was covered in OSB and the new roof is much better looking since it is has no low spots anymore.