I'm confused about OSB grading and appropriate uses for it. Can anyone explain, or post links to useful refs?
There appear to be "classes" of use, including interior and underlying a flat roof (or in this case, a green roof). There also appear to be "classes" as a description of the quality (i.e. OSB2, OSB3) and the weather resistance of the boards themselves. However "class 2 use" (under a roof) seems to equate with "OSB3 class 3 materials". Class 2 materials aren't up to use in a class 2 scenario.
So what are class 2 & class 3 materials? What are they made of, what's the difference, how do I tell them apart?
What am I usually being sold? If the merchant says "Yeah, class 2, sell loads of it, make your roof lovely that. Never heard of class 3 though" do they mean material or usage class? Is this stuff really fit for roofing, or are they just being wrongly optimistic to sell the stuff?
Wickes list these products on-line (class 3 too), but they're only available in-store. Our local store doesn't stock them all, knows nothing of their merits, and they'd smashed the edges off the T&G anyway.