I've just had a new subfloor put down for the whole of the top floor of my house, using 18mm structural hardwood plywood. All of the sheets are glued down with PVA and are screwed in using Spax screws. There is also a 1/8" gap around each panel to accommodate for any expansion in the wood. The problem that I have is that one of the plywood sheets makes a creaking noise when stepping on it anywhere in the middle of the length of the panel, even over different joists. The top of the centre joist that the sheet of plywood rests on appears to be a couple of millimetres lower than the other joists. The carpenter who fitted the subfloor tried doubling up on screws but this just seemed to make the creaking problem slightly worse. I've tried taking all of the screws in the center of the plywood out (but it's still screwed in around the edges) in order to see if the wood is somehow rubbing on the screws, but the creaking noises are still there (even coming from the places where there are no screws). I'm thinking it must be the plywood sheet rubbing against the joists somehow, or perhaps it's the joists themselves that are creaking, but the strange this is, that the other sheets of plywood adjacent to this one sheet all seem to be fine (no creaking noises at all). Does anyone have any ideas what could be causing this issue? The carpenter who fitted it is threatening to come back and stick even more screws in the panel (which again just seemed to make the problem worse last time). Cheers, Andy
Is there any supports between the joists ( timber noggins or herringbone struts ) if not there may be more movement in that particular joist
Have you tried swapping that sheet just to see? Sounds pointless but I had to in one of my rooms in my old house and whether it was because the 2nd sheet I nailed differently but the squeeking disappeared
Not yet, although the thought did cross my mind. The problem is that the existing (creaky) sheet is glued down with PVA, so I guess it'll be a real pain in the ass to pull it back up again, I've got a feeling that this is where it's headed though. It would be odd if it were the sheet of wood itself as I intentionally bought good quality structural plywood because I wanted this stuff to last a lifetime.
I'm not sure if there are noggins between the joists under this particular board, I guess if my chippy has to resort to pulling the whole board up again, it's something I could suggest to him?
Update: I've had another carpenter come around and take a look and he reckons that the problem is because where the creaking is is mid span and the joists are thinner than in newer builds, so the joists are flexing a lot in those areas which is causing the creaking. So question is, what would be the best way to stiffen the floor by linking 6 joists together? Are we talking banging some noggins in between the joists or is there a better way? There's only access from above (after the plywood sheet has been ripped off) as the ceiling below is finished.
Just an idea, but since you are probably going to have a sheet of damaged ply, you could always cut it up to joist height lengths and glue and screw it to the side of the joists, as the ply shouldn't flex vertically, similar to i beams
Hi , if you have any walls directly underneath check them or metal stud walls. Remove the sheet and bounce on the joist you may be able to trace it . Check anything connecting the joist . As was suggested to reduce deflection ply both sides of the joist.
Hi Alban, there aren't any stud walls directly underneath where the ply sheet in question is situated. Would sistering just the middle 1.2 meters of those joists using wood of a similar height and thickness as the joists be better than using ply, or should we just be sticking to putting in one noggin between each joist at the centre of the floor?
I'd put noggins in, but not just one row, at least 2 maybe even 3. The more you use the more stable the floor will be.
All the other plywood boards in the room are already glued and screwed down, so we'll only have access to a 1.2m x 2.4m area underneath the board that will have to be ripped up. If the noggins are put in either side of the 1.2m gap (in line with the length edge of the board), would that be the best setup considering the limitations that we have here?
Just try it, then screw the ply down without the glue then at least you're not wrecking another sheet of ply if it's still squeaking and it needs to come back up
Hi , I would try and find the source of the squeak . Bounce on each joist to find rough area then remove the sheet . Check any joist hangers , pipes or anything touching the joist. Noggins will help reduce the joist twisting but the only way to reduce deflection will be to screw ply to both sides of the joist . Ta
Sounds daft but is it the floor that is squeaking...... we find sometimes that if can be the fixings in the partition walls that are flexing and as the floor moves causes the squeak
Not daft , on new builds they use metal stud partitions , walking on the floor causes the beams to deflect which in turn pulls the metal studwork down causing squeaks.
