I have a really dumb question. When securing plywood to trusses for a over garage storage space, do you overlap both ends on the truss? Images below.
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1The second one unless you like cutting. Trusses are not usually made to hold much weight.– crip659Commented Oct 3, 2023 at 21:26
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4Be safe: Before you add plywood for storage space, find the engineering specifications for these trusses. Some trusses are not designed to carry any weight at all on their bottom chord. When I needed trusses with a walkable space above my workshop, I had to order them specially made for the purpose, designed by an engineer. They came with a signed certificate for X load of dead weight per square foot and a separate live load specification.– MTACommented Oct 3, 2023 at 21:43
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1Good candidate for x-y question: please tell us why you’re doing this.– Aloysius DefenestrateCommented Oct 3, 2023 at 22:02
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Table 301.5 from the IRC specifies "uninhabitable attics without storage," "uninhabitable attics with limited storage," and "habitable attics and attics served with fixed stairs," where their definitions are in that table's footnotes. Basically, there's a rectangular shape that has to fit between the web members of your trusses for the space to qualify for storage. You should at least confirm that your "attic" qualifies as an "uninhabitable attic with limited storage" before plywooding the floor and piling stuff up there. If it doesn't qualify, then your trusses probably aren't built for stora– pophamCommented Oct 4, 2023 at 1:07
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I don't see any difference in the pics...they seem to just show a "time lapse" of the OP's intent. OP, what you show is fine, except if you have the option, I'd place the long edge of the plywood across the trusses (assuming this is an acceptable load).– HuesmannCommented Oct 4, 2023 at 11:35
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1 Answer
Overlap (one on top of the one next to it) - no. Try to land the joints on the trusses, yes, so for typical 1.5" thick truss material, there's only 3/4" of truss width for each bit of plywood where the joints are. If the building lacks precision sometimes additional material needs to be added so both bits of plywood have some support all the way across.
In any case, the plywood goes 90 degrees to what you've illustrated, so that each sheet bears on several trusses, and the sheets are staggered so the joints in one row are on different trusses than the joints in the row next to them. For a bit more cost using tongue and groove plywood or OSB helps to make the floor act more like a single sheet where the joints are.
