Securing a 3/4" sub-floor

[scuba_dave]

The IRC does not give an option using screws to mount subfloor sheathing to wood floor joists. Table 602.3.1 calls for 8d common nailing. Refer to 503.2.3 that requires subfloor sheathing to be secured by table 602.3.1 with no reference of use of screws for subfloor securing only 8d common nails. Alternative methods are not forbidden but is required to be done with use of an engineer.

To mount a stud by toe nail to plate the same chart again does not refer to screws used for that purpose. The IRC rules call for either 3-8d or 2-16d to fasten a stud to a plate by toe nailing. Again alternative methods are nor forbidden but requires an engineer involved.

I would ask your AHJ to confirm what he or she rules on the subject.

Good Luck

Wg

I searched for info on this & found Wg's answer
It seems to me a floor that is just nailed will eventually squeek
The glue sounds like a good option & will help

But I'd also like to add screws to try to minimize or eliminate any long term squeeks.

Are deck screws a good choice?

[CR500]

I filled in my existing kitchen subfloor with deck screws. We'll see how many of them I hit when I start laying the hardwood. I can only think of two reasons why screws aren't allowed to meet code: they don't have the shear strength of a nail and you can get some lifting between the subfloor and joist. Deck screws typically have a greater cross-sectional area than drywall screws.

Before sheet rocking my kitchen ceiling, I ran a bead of polyurethane construction adhesive on either side of as many joists as I could reach (where it meets the subfloor for the room above). It seems to have greatly reduced squeeks in that floor.

[Fischer]

Construction adhesive is your best bet. The adhesive will make the entire floor and joists act like a single stressed skin unit. Tongue and groove will add to that strength. Ring shank nails will also work well. Screws applied correctly may be better yet, but will not be a cure all.

Here's what I do.

Try to make sure that your playwood is straight as possible before installation, that is lay it on a flat surface and weight it down, unless it is staight to start out. Layout enough adhesive to apply 1 sheet of plywood (between 1/4 and 3/8" bead) in a wavy pattern and doubled on the joists where joints fall. Walk and jump where needed before starting to nail or screw. Chalk lines are invaluable, just leave an inch or two over the line, because if your adhesive starts to set up it will leave a void. When using a nailer with ring shanks, stand over the floor joist, and nail between your feet. Your weight will help set it in. After you've done a sheet go back with a framing hammer and set the nails again. Same holds true with screws, but set your depth flush, and then after set go back a slightly countersink. This gives the plywood a chance to conform, and then you set the screws and bring it on down. This is not a production method of installation, but will yield much better results. If you set too deep to start out with, you have a chance of stripping out the threads in your joists, and make sure they're long enough.

[scuba_dave]

I used everything!!
Adhesive, nails & 2 1/2" screws - in that order
I don't think it will move :D