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Are drywall screws suitable for attaching a 3/4" tongue-and-groove plywood subfloor?

In this case, joists are 16" O.C. and no glue will be used.

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By "drywall screws", I think you are meaning 1 5/8" blued screws. I do not think that they would be a good choice. We usually shoot down plywood subflooring with 2 1/2" to 3" ring shank nails, however 2" to 2 1/2" decking screws work well, but just a lot more work. I would encourage you to use a little adhesive on top of the floor joists or strips of felt paper or Grace ice/water shield to avoid any squeaks later on.

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    What type of adhesive? – Joe Phillips Feb 9 '14 at 17:46
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    Any good construction adhesive, but i like PL200 or PL400. – shirlock homes Feb 10 '14 at 21:51
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I wouldn't. Drywall screws should only be used for drywall, and a temporary coat hanger. You want more strength and need less space for the threads to secure the subfloor. The drywall screws have a lot of thread to hold the drywall itself, but have very little shear strength.

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Nooooo, don't, over time they break. Floors bounce over joist and screws heads that are holding plywoods or OSB's are pulled, worst, the shear stress of wood and joist expansion over seasons will break them. I found that after removing a carpet and saw hundreds of heads screws not talking about all squeakings. Use proper floor screws, the savings can't justify the time spent to correct that, if you ever can.

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In the field between the joists, they are fine. As long as you use 3" construction screws to grab the joists and proper adhesives.

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    If you're attaching plywood to the joists, why would you use screws between the joists? – Tester101 Feb 25 '15 at 16:52

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