second sheet of plywood for stronger floor....

Old 03-22-11, 02:20 PM
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second sheet of plywood for stronger floor....

this was a posting in the sub-flooring section and someone suggested I post it here for more info\advice .

I recently leveled a floor in a room in my house by sistering 2x4s with nails and screwing/gluing new 3/4" plywood to the existing 3x12" joists to prepare for the 3 1/4" pre-finished oak floor I will be installing and I thought that I would add a second sheet of plywood to the sub-floor for strength until I posted this in the sub-flooring section and I now have some of concerns.
Can someone tell me if the second sheet of plywood that I am wanting to attach to the sub-floor for strength should be screwed, glued or both? In addition, should the second sheet be connected to the floor joists? All comments are appreciated.
Old 03-22-11, 03:44 PM
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Different part of the forum, same answers. Screwed with decking screws and not into the joists, and not glued. The disconnection factor mentioned by Johnny would apply here as well. More so in a tile installation, I believe.

Last edited by chandler; 03-22-11 at 05:15 PM.

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