Squeaky subfloor

Klopp · 04-10-2025 09:56PM #1

The main bedroom in our house has a squeaky floor, and today I tried fixing it. I removed the carpet and underlay found a 1/4-inch thick 8 x 4 plywood sheet laid over the joists. I screwed in 50mm fully threaded screws to the worst area along two sheets, but the squeak is still there.

I believe the problem is with the floor joists themselves. I’d probably need to remove all the flooring, but I’m not sure of the best approach to do is here, whether adding blocking between the joists would help or if adding long structural screws to secure the joist either end and relay the plywood with glue to the joists? There isbblocking in the middle of the the floor but nowhere else.

I’m looking for some advice on what the best approach to this is, maybe someone here who had a similar problem and managed to fix it permanently?

Hobby farmer · 05-10-2025 12:41AM

Try partial threaded screws, full threads won't always pull the ply tight to the joists. I'd back out the old screws first too.

10-10-20 · 05-10-2025 01:52PM

Yes, these lads or similar:

https://www.spax.com/pc-en/p/flooring-screw-fixing-thread-flat-countersunk-head-t-star-plus-cut-point-wirox.html

Note the high torque t-star bit which helps keep them straight.

Just be sure that there aren't any cables or pipes under the floor too.

Klopp · 05-10-2025 02:53PM

Thanks both. I will pick up a box of the partial threaded screws tomorrow.

Klopp · 06-10-2025 11:47AM

I replaced the old screws this morning, using partially threaded screws and new holes, but it didn’t make any difference, it’s still squeaky. I’m starting to think the issue might be with the bottom plate on the stud wall behind the skirting board, especially since that’s where the squeaking and noise seem to be coming from that side, but there are squeaks elsewhere on the floor, so maybe it is the joist.

Witcher · 06-10-2025 06:56PM

https://www.boards.ie/discussion/comment/123882217#Comment_123882217

ProperDIY on Youtube had the same issue with the wall squeaking when walking near it.

https://youtu.be/6---TEioiW8?si=-jU__AerG-Hrdl4l

Klopp · 07-10-2025 10:06AM

Thanks for sharing the video. I do think this might be part of the issue I’m having as well. The next step is to remove the skirtboard to get a better look at what’s going on behind.

Also starting to think the screws I used might be too long. I went with 55mm partial threads, but with the plywood only being 1/4 thick, 45mm probably would have been a better choice.

steamdave · 07-10-2025 03:13PM

https://www.boards.ie/discussion/comment/123885023#Comment_123885023

1/4" plywood? Seems very thin to me. Think flooring grade chipboard/OSB which is normally 20mm - 3/4".

Dave

Klopp · 07-10-2025 03:30PM

https://www.boards.ie/discussion/comment/123885996#Comment_123885996

I keep thinking it's a 1/4", but you're right, it's actually 3/14" thick plywood.

Squeaky subfloor

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