Are 1/8″ gaps in OSB/Plywood cumulative over a span?
The APS recommends keeping a 1/8″ gap between OSB or plywood sheets when used on roofs, floors, or walls. That makes a lot of sense since both types of sheathing absolutely will expand and contract. But I don’t get how that works out of a span.
I have a wall span of about 27′ and so it will require 6 full sheets and 1 partial sheet of 4×8 OSB when installed vertically. That’s also 6 gaps between the panels. If each gap is spaced at 1/8″, isn’t the final panel going to be “shifted” 6/8″ or 3/4″ over?
That is, I have studs that are 24″ O.C. and so my first panel will lay centered on the stud — 3/4″ over. The next panel will be 1/8″ over, though, and so it will be 7/8″ on the stud. Next one is shifted another 1/8″ and so it will lay at 1″ on the stud. And so on until the final stud won’t be starting on a stud at all since it’ll all be shifted over 3/4″ to a total of 1-1/2″.
(This is ignoring using double studs or 4x4s on panel edges)
Are APS-rated panels actually 1/8″ thinner than 4′ and 8′? Or what fundamental thing am I missing?
Replies
If the panel is stamped "sized for spacing" it was made undersized at the plant to accommodate the spacing. My experience is that most panels are back to full width if they sit around long. When that happens you either don't space or trim one once in a while, guaranteed to slow you up.