creaking structural engineered floor

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Hi there,

Here I am again learning the path of proper build/diy. This time a question about squeaking floors.

We bought a house, 1930-ies end of terrance, three years ago, and I got excited about the idea of underfloor heating (bad idea on suspended timber floor! but it is a separate post). So we lifted the floor boards in the master bedroom, laid out insulation between the joists, then aluminium spreaders, then pipes and then nice structural engineered wood floor. This one, if someone is interested: https://www.flooringsupplies.co.uk/...ak_ironbark_mountain_engineered_wood_flooring

The floor was screwed onto the joists with small (even tiny) hidden tongue-tite screws hidden in tongue and grove between the planks
https://www.screwfix.com/p/tongue-tite-screws-3-5-x-45mm-200-pack/85991

Also, small strips of simply underlay were laid onto the joists under the boards to prevent squeaking after the builder's advice. The floor boards were also given time to "accommodate" couple of weeks before screwing them in, although the heating itself was not on at that time.

Initially the floor was fine but then it has probably started to dry further with the underfloor heating and strong squeaks has developed, especially in the "free areas" where heavy furniture (like bed) is not holding it down.

I think the problem is two fold:
- the old joists have sagged over time and towards the middle of the room it is very slightly lower than the sides, so the engineered wood boards spring on top of the joists below. And we did not straighten the joists prior to laying the floor
- the small screws were inadequate and not holding the boards to the joists, so they spring up and down
- and the underfloor heating itself and shrinkage of wood b/c of it was a bad idea in general, but it is not a primary thing to blame at the moment

The question now can the creaking be fixed now, without lifting and redoing the whole thing again?

I am thinking in direction:
- maybe drill some pivot holes and try to fill in epoxy resin under the springing boards so they have more support? And then screw them in with a proper bigger screws (what size shall I use?)
- How would you locate the exact joists positions so I don't go over the u/h pipes?

Any advice and ideas appreciated.

Thanks,
D
 
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I went to a job recently wher solid oak floor has been laid over wet underfloor heating. I was surprised as to me, thats a massive no no. However the fitters said its fine as they had face screwed every single board down. The screws were fitted in counterbored holes and oak plugs to finish. Surprisingly the plugs look ok.

Maybe that might be a solution? (Depending how the floor is finished?). Or maybe just screw and plug under the bed etc.

I dont know how you find the joists, maybe a strong neodymium magnet to find the screws
 
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Even if it is structural, you should not be fixing floor boards down with one screw, nor one screw just in the tongue at that.

Two (or three for wide boards) fixings across the width of the board.
 
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Thanks Notch, thanks Woody. Yes, the lesson learned I guess regarding fixing them. Aesthetics aside, I will need to screw them in properly

The question now - shall I try to fill somehow the small gap under the engineered floor to the sagged joists, so floor boards have more support underneath and spring less up and down, or just screw them in tightly, hoping they will not spring back up? This is why I was thinking to try to fill in epoxy through the holes, so it will solidify and create some support, although not sure how practical it is...
 
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Thanks Notch, thanks Woody. Yes, the lesson learned I guess regarding fixing them. Aesthetics aside, I will need to screw them in properly

The question now - shall I try to fill somehow the small gap under the engineered floor to the sagged joists, so floor boards have more support underneath and spring less up and down, or just screw them in tightly, hoping they will not spring back up? This is why I was thinking to try to fill in epoxy through the holes, so it will solidify and create some support, although not sure how practical it is...

I think if you arent taking up the floor, then your only option is screwing down the boards tight.

If face fixing, you might want a shank hole a bit bigger than the screw for movement. The idea of a fixed floor is that each board can only epand and contract within its own space, if the screw holes are tight, there isnt any free movement -although in reality nothing will stop a timber board moving, the screw or the joist would move.
 
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I think if you arent taking up the floor, then your only option is screwing down the boards tight.

If face fixing, you might want a shank hole a bit bigger than the screw for movement. The idea of a fixed floor is that each board can only epand and contract within its own space, if the screw holes are tight, there isnt any free movement -although in reality nothing will stop a timber board moving, the screw or the joist would move.

Just a face fix at the moment. Although I am confused as why wider shank hole should work. The boards don't squeak when heating is off or on, they are actually very stable to it. They squeak when I am stepping on them, and this is exactly when I feel slight down movement, so unloaded they are slightly above the sagged joists and when I step on them, I press them down and they squeak.. So I would think I either pin them down tightly or try to first fill in the gap somehow under them and then still screw them down tightly
 
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I'd suggest just screwing down tight to the joist. Anything else, you couldnt guarantee.

Also remember that you should not use mild steel screw with oak as the tanin in the oak reacts with the steel to cause black stains.
 
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The wider shank hole wont make any difference to your creaaking, it will allow each board to expand and contract a tiny bit -within the width of the board.

Im not sure how you can get anything under the board to act as a spacer -I suppose you are saying you could inject the hole with something that sets. I sippose that could help although I imagine it will come back up the hole! Maybe a hydraulic grease pump might work!
 
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Thanks guys.

I am planning to use decking screws 4.5 x 65mm (roughly 3 times floor boards thickness of 20mm), something like:
https://www.screwfix.com/p/timbadec...teel-decking-screws-4-5-x-65mm-100-pack/95751

drilling a 2mm pivot hole all the way into the joist and bigger clearance hole of about 5mm in the engineered floor board itself (or even bigger clearance hole? to allow for expansion/contraction as per Notch7 comment?)

Sounds right?

PS. Update on attempts so far:
- I've tried talc powder into some board gaps over the weekend. Left it for a day, stepping over, trying to get powder inside. No noticeable change, maybe a tiny bit better.
- then got an idea to try to put some oil (lubrication?) - tried in one small area - terrible. Getting very, very loud creaks now at that place
- so need a proper fix with the screws, will just try to sink them nicely and evenly in the areas where the creaks are the most noisy
 
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