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Screw pattern and size for 3/4" plywood subfloor?

Screw pattern and size for 3/4" plywood subfloor?


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Old 08-14-14, 10:20 AM
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Screw pattern and size for 3/4" plywood subfloor?

Hey there, I'm getting read to screw and glue some subfloor in. I bought subfloor glue and will be putting it on the joists (should I just do a zigzag?) before I screw them in. To screw them in, I was planning on getting #8 2" fully threaded construction screws.

Is that a good idea? Should I get partially threaded instead? Should I alternate between full and partially threaded? How many inches between the screws?

Thanks a ton guys!
 
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Old 08-14-14, 12:54 PM
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Not sure what a "construction" screw is, but I recommend using Torx head decking screws. Partially threaded will tend to pull the wood down to the joists better. 8-10" in the field is sufficient. Now, if you are going over this subflooring with another layer, no glue and intentionally miss the joists with the next set of screws.
 
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Old 08-14-14, 01:14 PM
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Thanks chandler, you're the man!

Nope, just the one layer. I'm a little worried because the plywood is ever so slightly bowed. I hope that'll fix once I screw and glue it...
 
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Old 08-14-14, 01:28 PM
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Are you using Advantech or similar subflooring or just plywood? No big deal, just Advantech is a subfloor which is tongue and groove and is wax impregnated to prevent water damage during construction.
 
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Old 08-14-14, 02:01 PM
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MULTI-MATERIAL CONSTRUCTION SCREWS

and

Grip-Rite 2 in. Construction Screw (1 lb.-Box)-2GCS1 at The Home Depot

The second one looks much like a deck screw except uncoated.

The SPAX is probably much stronger, but I imagine more expensive.

I'd use the partial thread, you want to pull the layers together and a full thread can sometimes cause the upper piece to walk up slightly.
 
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Old 08-14-14, 02:16 PM
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Thanks guys! Chandler, I looked everywhere I could for adventech. EVERYWHERE! My gosh that stuff is hard to find. All osb is generic in my area.

Weird question: let's say I can't find #8 2" coated screws. Could I use #9 2"? For some reason that size (coated) is not common.
 
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Old 08-14-14, 02:18 PM
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Yes, #9 just has a larger shank, but will hold just fine. The screws Vic mentioned is good. I just didn't want you using sheetrock screws
 
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Old 08-14-14, 02:26 PM
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Hahaha, hey, I'm stupid when it comes to this stuff but not that stupid; I eventually pick up on the stuff you guys tell me!

I knew it was just a slight size difference but asked because knowing my luck I'd end up ruining something due to some unknown rule lol.

Well, thanks again mr chandler!
 
 

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