Started by MushCreek, July 15, 2011, 06:21:19 PM
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QuoteYou might add to your last post, something like this...Good shear diaphragm action of a floor, roof or wall diaphragm depends on fairly full sheets at the edges of the diaphragm to prevent racking or provide the shear action back into the diaphragm. That is, good nailing, and tighter nail spacing, btwn. the rim jst. or the edge jst. and adjacent jsts. across a full sheet of sheathing. The full sheet is a very effective shear panel, while a narrow piece of the same material suffers from the same weak shear joint as shiplap sheathing suffers from; it allows slip at this joint instead of transferring shear across the joint. This nailing may be the primary lateral load connection btwn. the floor diaphragm and a ledger or rim jst. End nailing and toenailing btwn. jsts. certainly isn't. Diagonal shiplap sheathing provided some diaphragm action by virtue of a truss type diagonal action w.r.t. the jsts. While shiplap perpendicular to the jsts. did not provide much diaphragm action, except that the many joints with the jsts. and each piece of shiplap, and two nails at each joint developed some moment btwn. the nails in that joint, and thus resisted some racking. Plywood or OSB sheathing is a far superior material for resisting the shear we are dealing with. Thus, it is not a good idea to use a narrow strip, 8' long, or a 4' wide piece spanning only one jst. space, at any edge of a diaphragm.
Quote from: MushCreek on July 15, 2011, 06:21:19 PM....plywood, specifically. As long as I've been alive, most building materials are based around 48" wide sheets, or things that divide evenly into it- 12", 16", 24". Along comes T&G sheathing, and it only measures 47-1/2". How are you suppose to compensate for that? Make your building a little smaller, and space joists on 15.8125" centers? I went to a lot of trouble to try to work with standard sheet goods, and now I don't know what to do about floor sheathing. Seems like T&G is a good idea, but......