How can I strengthen this squeaky new floor?

[redhexagonal]

This floor was replaced recently because the joists were not level and the boards were in poor condition. The joists have been levelled with additional timber, and the new 22m chipboard is glued and screwed in place (although in this room I can’t see as much glue in the cracks, i think they must have been running low) .
However a nasty creaking noise has emerged along the larger of the red outlined areas, over a joist. There is also visible movement of the corner of the board circled in the smaller area which unfortunately is in a high traffic area .
I don’t really want to cut into the boards , and I was thinking of cutting into the plasterboard ceiling downstairs, then glueing and screwing in some noggins to support the floating corner, then maybe trying to squeeze more glue along the creaking joist somehow, and then putting more screws into it from above. Is this a mad plan? Any other ideas to stop the dreaded creaking?

(There is little chance of getting the builder who did this back as we fell out because he wouldn't fix damage done during the job.)

 

[big-all]

you seem to have a row off screws within your circle with joints just to the side all joints should ideally be on a joist or noggin especially in high load areas
if the screws are tight suspect the noise and movement is in the joints to either side
sometimes iff you have a say 1-2mm gap on the surface scrape out with a screwdriver and a bead off d4 glue place and worked in then replaced until gap full
now i am not talking about opening to a trench just clean out to give a chance off penetration off hopefully say 10-15mm in depth but at least 5-7mm deep to give enough support so the top layer stays intact rather than delaminate
Sometimes countersinking screws in an unsupported joint with glued pumped in will help--- the glue sticking and the thread on the perhaps 4/4.5mm screw causing resistance to movement the screw will point into space underneath so care required for services [cables and wires ] if you dont know where services are then smaller perhaps 20mmx 3.5/4mm through the zigzag on the joint although not as good grip wise are better than nothing
but always either fill a pilot hole or remove a self countersinking screw and pump the hole full off non foaming d4 or similar glue before driving the screw home

 

[big-all]

also worth trying if you are sure the noise is in the circled area remove every other screw and pump in push in glue into the holes before reinserting the screw then fill the other half
now glue is not ideal everywhere as it can cause other maintenance problems but if it solves the noise problem the extra work involved to remove and re-install iff required is worth the effort

 

[redhexagonal]

also worth trying if you are sure the noise is in the circled area remove every other screw and pump in push in glue into the holes before reinserting the screw then fill the other half
now glue is not ideal everywhere as it can cause other maintenance problems but if it solves the noise problem the extra work involved to remove and re-install iff required is worth the effort

Is it worth putting in extra screws? There are only four screws across the 600mm span. Could I put them every 10cm instead of 20cm, or could that weaken the board?

 

[big-all]

its very very risky as you dont know where the services are so best to try tightening the present screws as the safest first option

 

[redhexagonal]

its very very risky as you dont know where the services are so best to try tightening the present screws as the safest first option

Im pretty sure there are no services along that joist, I had a look when the floor was up. Can too many screws weaken the board? 10cm spacing ok?

 

[robinbanks]

If you wind all the screws out, does it still squeak?

 

[big-all]

Im pretty sure there are no services along that joist, I had a look when the floor was up. Can too many screws weaken the board? 10cm spacing ok?

6-9" whatever gives you equal spacings between fixings already there

 

[redhexagonal]

If you wind all the screws out, does it still squeak

I took out 4 screws on the most squeaky board and it was just as bad if not worse

 

[redhexagonal]

6-9" whatever gives you equal spacings between fixings already there

There are 4 across the boards at the moment so putting in 3 more screws makes 10cm spacing (4 inches), is that too close?

 

[Dereekoo]

Is it worth putting in extra screws? There are only four screws across the 600mm span. Could I put them every 10cm instead of 20cm, or could that weaken the board?

No, put them in at 50 centres and board would still be ok

 

[redhexagonal]

No, put them in at 50 centres and board would still be ok

Do you mean 50mm?

 

[big-all]

No, put them in at 50 centres and board would still be ok

yes i must admit i thought it was 4 screws along a 1200 board so 45/400/800/1155 hence my comments off 6-9" for extra [7-8"] 50mm although wont do damage as such it will just be far more screws to remove if it still doesnt work to cure
i suspect the floor has jacked up in areas [screw pushes floor off the joists a bit before cutting in ]so removing screws loading up with a foot and screwing tight with extra glue will help but as we all know there can be several causes and possible solutions

 

[JohnD]

Chipboard

 

[big-all]

Chipboard

love it or hate it its what we have to deal with