new floor creaks :-(

[JohnD]

I have replaced my old chipboard kitchen floor with 18mm T&G ply. It is 2.5 metres wide. Boards are screwed 50mm from each edge, and at the centre line. Kitchen floor is about 3300mm long but I had previously renewed the end part of it so my new section is about 2400 long (just one trimmed board long).

I have lost the screw box but they are 40mm CSK, shank looks like 4mm and threads 5mm. They are in pretty tight and have pulled themselves into the countersink. T&Gs feel tight but the joint is visible and you could put a fingernail in it.

I have noticed it creaking in places a few days after rolling back the vinyl and pushing the cooker and other appliances back into place.

I have a feeling the floor has moved a bit since I pushed the appliances back from the far side. I walked about on it beforehand listening for creaks and it seemed OK. Joists are modern sized at 14" centres with herringbone strutting down the centre of the room. there are a few sistered joists to support the 3 steps coming into the kitchen middle of one side, and a partial half-height partition at the end of the kitchen part.

I suppose the answer will be more, bigger, tighter screws... but is there something I did wrong?

 

[Deluks]

... but is there something I did wrong?

Yes. You fitted it all after following advice from wallies on the internet!

 

[JohnD]

 

[mattysupra]

john, add me as a friend so i can p.m you.

 

[JohnD]

 

[mattysupra]

im going to guess that the timber was wet when installed and has shrunk very slightly around the screws. Or it was very dry and has expanded a bit putting pressure on the screws. ? Did you acclimatise the plywood? where was it stored before you laid it?

 

[JohnD]

the plywood has been stored indoors, on the landing just outside the kitchen door, for a couple of months. Not at all wet. It was stored on end, about 10 pieces leaning on each other, almost upright against the wall.

The kitchen floor has a "garage" below but it is used for storage so no rainy car.

 

[mattysupra]

i dont know then. maybe crap screws? Strange one.

 

[JohnD]

it seems to be worse in front of the cooker and dishwasher, my guess is the floor deformed slightly from the weight since I pushed the appliances back. Not that I really know, but it didn't creak until then. If I stand above one joist, then shift my weight a metre or so, so I'm standing on the next but one, it creaks under me. then when I transfer my weight back it creaks again.

I think I will have to roll up the floor covering from the other side and replace with thicker screws, with the appliances in place.

 

[2scoops0406]

Are the joists themselves totally solid?

 

[JohnD]

yes, so far as I can see. I was levering up the old boards and clambering about on the joists working on pipes and cables, and saw no sign or sound of movement. they are built into dense try-wall concrete blocks, IIRC bedded in mortar (i did not notice any metal or plastic in the wall)

it is on the first floor so no damp.

however now you mention it I have got at least one uneven floor upstairs, so maybe the carpenter's mate who did the flooring was not an expert. It is part of a group of self-build houses and although they were pretty careful, in a few places you can see lack of skill. My next door neighbour told me that he ripped up his floors and shimmed them level, I did not think of that and did not try them with my level.

Maybe that's the trouble damn.

 

[big-all]

just a though

i wonder if some off the screws have "pushed " a gap between boards and joists

are the screws fully threaded!!!
if they are you could in the area concerned unscrew then retighten standing/kneeling over the screw or using a screw with an unthread full shank like a 8x2" from screwfix or toolstation!!!

 

[JohnD]

no, they have a plain shank. wish i could find the box. I thought I had torqued then down well

so I'm now thinking: deflection under load; or unlevel joists.

I think I might have to take up (at least) one board and try across the joists with a long straight edge/level. if they're OK I'll pre-load the floor with appliances before using bigger screws. If not I hope I can plane down the high ones(s)

 

[big-all]

afraid lifting one board wont give you a true reading as any boards attached will help level them out

just checking your joists are 400mm apart and boards are secured every 400 to 600mm with support under where the boards join!!!!

 

[JohnD]

afraid lifting one board wont give you a true reading as any boards attached will help level them out

just checking your joists are 400mm apart and boards are secured every 400 to 600mm with support under where the boards join!!!!

seems to be 14" but yes, boards are 2400x600, joist under every short edge (I had to trim them to get this), screws 50mm in from edge and at centre line of each board on every joist