In ’94 I built my parents a house; only one problem so far. There is one spot in the house with a twenty foot long squeak that traverses two rooms. It is a lengthwise (perpendicular to joists) t&g plywood joint, at about midspan between two beams. It’s a trus-joist floor with Com-ply glued and ringshanked to it, (Com-ply is a product with fir veneers and a layer of fibreboard in the middle, for some reason). No joist hangers nearby, no squeaking partition nails. I can get at it from beneath, but will have to remove carpeting and pad to get at the top. The only thing I can think of which might work is squirting glue down and up into the joint. That would probably only work if it is the shoulders of the boards rubbing together. I’m screwed if it’s the tongue, probably. So if I do this, what sort of glue should I use? As usual, there’s some sort of colored waxy paint on the joints to protect it from weather. Will anything stick to that? Any suggestions? This is the only spot in 3200 square feet of floor with a noise issue, and it is definitely coming from the plywood joint.
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Have you considered installing blocking from below between the joists along the line of the offending joint? If the subfloor joint cannot flex it cannot squeak.
I should think that you could install 2x6 blocks up flat and tight against the T&G subfloor with the ends snug against the joists. You would liberally smear them with construction adhesive, place them with 1 1/2" overlapping the subfloor joint and end nail through the joists. By alternating them right and left of the joint, you would always have 4" of access to end nail each block at both ends and 1 1/2" under the joint.
Yes, I gave that some thought, although I was thinking of driving 2 1/2 inch screws up through the 2x6 at an angle on both sides of the joint. My first thought of squeezing glue into the joint was to get something in between the rubbing edges. Why do you think this joint is squeaking? I've never had this particular problem before, and that joint is seventy feet long, but only squeaks in one area. Very puzzling.
If the subfloor is a fiberboard sandwich, I wouldn't expect much hold from those screws.
Normally the first thought would be that someone forgot to glue those sheets in the problem area, but you did the work yourself so you know it was glued and ring-shank nailed.
Is it possible that a couple of the sheets had damaged tongues or a side of the grooves that have since broken completely and are now allowing the adjoining edges to move past each other and squeak?
20 feet is only 10 or 15 blocks. I would think the first block or two could be tested before doing any more.
Sounds like a problem with the tongue and grove alignment in the joint.
I had that happen with T&G plywood some 19 years ago. The squeak didn't show up for 5 years. That is about how long it took for the tongue to flex enough to break loose from the edge of the plywood. I put blocking under the joints I could get to from underneath, and later, when hardwood floors replaced the carpet I screwed the othe areas down.
Since you can get to the joints from the underside, you can check the them by slipping a knife blade up into them. If the tongue is broken the blade will slide in further on those joints. If they arent broken, bstill missaligned a lite, you will see a gap above the joist on one side or other of the joint. There is no pulling it down with screws through blocking into the bottom of the subfloor.
What I did was screw and glue the blocking to the subfloor from the bottom, then push it up a little and nail it in place through the joist.
I found some areas where as little as a 1/16" missalignment of the toungue and groove, and the shrinking of the joist as they dried out over the years, to be enough to cause a squeak.
"I'm screwed if it's the
"I'm screwed if it's the tongue, probably."
Work some talcum powder into the floorboard joint from above.
Jeff