Been a subcontracor for 20 years, 3 years ago I GC’d my own house, 2600 sq ft Cape.
Followed the guidelines of the book “Building in a Cold Climate” (SE CONN.), framed the exterior 2×6 24″ oc. Framer said OSB was the way to go on wall sheathing, there was some cost savings so I said sure. Did not know at the time he had never used it.
He’s gone, wire and plumb the house, cleaning up for inspection, throwing stuff out the window into the dumpster when I look down the side of the house and see waves, BIG WAVES. I freak out and call the framer to look at it, he says the OSB is defective and to get the lumberyard out to look at it.
The rep from the yard shows up, looks at it and says it was not installed properly and that it must be gapped for expansion just like plywood. Go round and round with the framer (was not paid in full yet, thank the Lord) he finally admits he had never used OSB before and had no clue. He ended up saw cutting all seams in order to give the OSB room to expand and flatten out. We had to wait about 2 weeks and still replaced about 8 sheets of OSB and had to rewrap the house all over again.
Anyways I am now building again (will not touch OSB with a ten foot pole) and was looking over some work that my “future” framer has done and noticed he uses only plywood sheathing but there are no gaps for expansion!!!!. Is this right , should I ask that he gap the plywood on my house?
Replies
OSB works fine, but you should place a framing nail between sheets before nailing, maybe more if you live in a humid area. I have had the experience where a few saw cuts have to be made because of expansion but nothing serious. OSB is cheaper than plywood and if installed correctly does just as good of a job.
5/8" T&G OSB on floors can give you trouble if rain gets at it. Water will cause expansion and in my opinion the solidness of the floor is brought into question. Again if you can keep it dry OSB is cheaper and a good product. If it gets rained on and soaked more than 2 or 3 times you might have a problem with expansion.