New Sub Floor Squeaks

My partner and I just built a new 5/8" plywood subfloor (10' x 22') that is nailed to a frame of pressure-treated 2x4's that is supported by cement blocks and bricks.

One plywood (4'x8' board) has a very loud squeak when you walk on it, even though we've put more nails and screws into that board than any other.

Is there anything we can do at this point short of tearing out that board?

Here is a pic of the frame and foundation at an early stage of the project:

The best way to avoid squeaks is to lay down construction adhesive on top of all the joists before you lay down the plywood. A little late for that, but you might need to take up that one piece.

Given your construction method, the squeak could be a joist slipping on a brick, also.

i never use nails. only screws. i never nail. too risky.

david
- also, the gooey stuff jimbo mentioned would prevent rubbing and resulting squeaks too.
But somehow i think the biggest squeaks come from two 4'x8' sheets rubbing against each other.
Did you leave a gap?

If the subfloor isn't T&G edges, and you didn't support them, you may never get the squeak out. Squeaks mean movement, movement is not good. I'd have to run some numbers to see what kind of deflection ratings you'd get from that arrangement. Not sure it would meet codes. A second layer of minimum 3/8" on top, put on an offset and screwed should solve it if you want to go to that trouble. To make it even stronger, use a woodworking glue like Titebond II, spread and screw it on before the glue skins over. Dont' try this with a construction adhesive you pump out with a caulking gun, as you'll have voids and more potential squeaks. A second layer (of the same thickness) doubles the strength; gluing it increases that by a factor of 5. Gluing not done right creates lots of problems, though.

Good news. We put in screws every 2-3 inches in that board until the squeak went away. They love their floor and we got paid.

I am just wondering Eric, it may had fixed the squeak but did it fix the problem why it squeaked?

Yes.

The squeak was due to a slight warp in the wood. So, it needed more screws to straighten it out.

If the squeak had been due to a foundation problem, it wouldn't matter how many screws we put in there. It would still be squeaking.

JMHO- 2 X 4's are way to small for floor joist on 16" centers- especially w/ a 10ft span. I would have used at least 2X8 on 16"-And I it has a wall on it - 2 X 10's. Plus I would have used ¾' T & G plywood - which I glue, nail (ring shank), then screw. I think the squeaks will return....

Of course you are right.

A couple of points:

I misquoted. The span was only 8 ft. with 16 inch centers.

That room tends to flood out during monsoon season, and since we don't think the owner will effectively deal with that issue, we decided to go with pressure treated 2x4's sitting up an extra few inches off the ground on blocks and bricks instead of 2x6's or 2x8's sitting closer to the ground.

Also, we would have lost the job if we bid much more than we did, and the floor would be worth more than the entire dilapidated bungalow is worth.