A. Ken Smith responds: There's no reason you shouldn't use OSB, as long as there's no risk of it getting wet (if it does, it swells and comes apart). First, make sure that the diagonal board subflooring is screwed down and that there are no squeaks. Then lay the OSB in plenty of construction adhesive and screw it to the subflooring. The carpet should install just fine.
Ken Smith owns and operates Smitty's Flooring Specialties in Randolph, Vt. He is author of the article "A Contractor's Guide to Carpeting" (4/93).
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