Nailing floor with glue versus screwing floor without glue--which is better?

[Sasquatch]

For the house we're having built, it's time to build the floor deck. I'm not doing the work, but I'm curious... What's the better method for building a floor deck? ...nailing the floor boards to the joists with glue or construction adhesive? ...or screwing the floor boards to the joists without glue? My builder told me that they typically screw the boards to the joists without glue, but my brother told me that he has always nailed the floor boards to the joists with construction adhesive. Which is the better technique? Will screws without glue work well, or will we end up with squeaks? (I think this is 3/4" OSB on top of 14" engineered joists.) Please advise. Thanks! - John

[RicodJour]

Hey John. Crossposting in this instance would not have been a bad thing. Everyone would get to see the replies and they wouldn't bother posting if the same advice had already been given. It also makes it marginally easier for you to read the replies (depending on your newsreader).

R

[Robert Allison]

We use construction adhesive on all floors, tack them down with nails, then go back and screw everything down. You can screw them down without adhesive, but the little bit of extra cost is good insurance in my book. If you nail them down (which I detest), then use ring shank nails and adhesive.

[Sasquatch]

So I'm getting the impression that screws+glue is *DEFINITELY* better than nails alone. But it sounds like screws by themselves, even without glue, is a pretty decent technique, too. Would you say that screws alone is just about as good as nails+glue?

[RicodJour]

This is what I mean about the crossposting. I answered this for you already. From my reply to your post in alt.architecture:

"Nailed and glued is better for typical stick-built framing. If you could assure very dry framing lumber, thereby eliminating most shrinkage due to moisture loss in the wood, the screws would be as good. Since you're going with engineered joists and OSB, it's a toss up. I'd tell the builder to use glue and screw it. Cheap insurance and he doesn't have to change his fastening method and tools."

R

[Bob Morrison]

And this is the response I gave in alt.architecture:

I've recently seen a new floor installation method that uses a strip of closed cell foam tape on top of the joists instead of glue. The sheathing is then put down using #8 screws on the same pattern as one would use 10d nails. The foam has adhesive on one side and a slick surface on the other to make sliding the sheathing into place easier. I'm told that the adhesive on the foam works better on wet surfaces than the normal construction adhesive and unlike glue won't spread to surfaces where you don't want it. This floor is good and solid and does not squeak.

[marson]

i nail and glue my subfloors. have had only one squeaky floor, and that was because the owner/general contractor covered it with a half assed sheet of poly during a very wet spell during construction and it got VERY wet (plastic trapped more moisture than it repelled). i just started using the new foam subfloor adhesive applied with a "professional" foam gun. really like how fast and easy it is.

Bob Morris> > So I'm getting the impression that screws+glue is *DEFINITELY* better

[Wayne Whitney]

Hi Bob, I believe a #8 screw has a root diameter of 0.112" while a 10d nail has a diameter of 0.148". So presumably the #8 screw has a lower shear strength. If so, does this difference matter in earthquake country?

Thanks, Wayne

[Bob Morrison]

I was thinking of the Simpson Quikdrive system which uses #8 screws and has test data to back up their claims.

[Wayne Whitney]

Thanks for the pointer! Wayne

[RicodJour]

The screw steel is harder and less ductile than that of a nail. You should never use drywall screws to attach the subfloor - deck screws at the least. If you're building in earthquake and hurricane territory, or the screws will be experiencing significant shear, the screws should be rated like those Bob mentioned.

R