Creaking of new 1st floor

[SimonD]

My suspicion is that the problem lies with the joist installation rather than the subfloor per se. With carcassing timber it's not uncommon to get them with several mm difference in finished dimensions, even when they're regularised, because they're nominal dimensions. Similarly, if a joist or more was slightly bent vertically and installed with the curve concave instead of convex, for example, you'll likely get subfloor movement, even when screwed. If there's insufficient glue, this will not help.

 

If the joists don't provide a sufficient level structure, even installing plywood is risky as any undulation will still need to be spanned by the subfloor. At 400cc that could mean an 800 cc span which is above the recommended max of 600cc even for 22mm ply.

[tanneja]

Thanks @SimonD I am struggling with your second passage unfortunately.  Should I be taking from your comment that 18mm chipboard (as in place now) is more suited / recommended relative to the properties the layman in me presumes we would get from 22mm ply?

[LA3222]

16 minutes ago, tanneja said:

Thanks @SimonD I am struggling with your second passage unfortunately.  Should I be taking from your comment that 18mm chipboard (as in place now) is more suited / recommended relative to the properties the layman in me presumes we would get from 22mm ply?

Think what he is getting at is if the joist under the floor deck is slightly concave then the floor deck is only in contact with the joists either side of the the affected joist.

 

You then have a situation where the span between joists that support the floor deck is a minimum of 800mm assuming the joist centres are 400mm.

 

Max centres for 22mm floor deck is 600mm so upgrading the floor deck to 22mm will not solve the issue.

[TonyT]

If you did decide go down the removal route and remove the 18mm chipboard  would 22mm chipboard be bettter due to the tongue and groove (T&G) rather than butting 22mm plywood?

you would also have to add additional noggins under the ply to catch each edge as it’s not T&G, so a lot more work.

 

are you able to post some pictures of the joist installation, as this is probably the problem area, as most joiners can lay chipboard flooring and have been doing so for decades ,but not engineered joists

[tanneja]

Ok understood thanks, I guess we would have access to see if there is some inherent bend at the timber top surface if we remove, I can't tell while all together, as while any camber should be evident from below if the timber is of uniform thickness, it sounds like there could be any number of imperfections from the materials used, to the installation, causing the creaking, so direct inspection is the best chance to identify. 

 

The joist installation is on hangars on a wall plate, I can try do pictures at some point, they are nailed into the metal hangars.

 

I am a layman, so if I am told 22mm chipboard will outperform 22mm ply, that is valuable information.  I could go for a thicker material up to around 30mm if that further helps our cause.  I just have relatively little faith in chipboard.  Asking friends with renovated houses with 18mm chipboard, all by different builders, all say their 1st floors squeak and so they avoid stepping in places, that drives my scepticism of any chipboard, it seems to me it is cheap rather than having advantageous properties relative to other sheet material.

[SimonD]

 43 minutes ago, tanneja said:

Thanks @SimonD I am struggling with your second passage unfortunately.  Should I be taking from your comment that 18mm chipboard (as in place now) is more suited / recommended relative to the properties the layman in me presumes we would get from 22mm ply?

 

@LA3222 's explanation is spot on. Much better put than mine! ?

 

I would go for plywood subfloor over chipboard any day. Whilst chipboard floor may well be ok, I personally don't like it that much but that's just personal preference and many chipboard installations are just fine.So I'm not saying chipboard is more suited. I think plywood is a better product. However, re the plywood, 22mm is overkill as it's usually used in commercial floor applications where heavier floor loads are design for. You'd be absolutely fine with 18mm plywood at 400 centres. 22mm would be belt and braces. However, I would recommend carefully checking the joist installation prior to laying any new subfloor.

 

I don't know if you've already said this but do use the TG4 (tongue & groove 4 sides) plywood flooring sheets.

 

Now, you can use tg4 plywood as a floating floor, but my worry about putting this straight over your existing floors is that if there is some defect in the joist installation, it may not resolve the problem of subfloor creaks. Although you could lay a large 18mm sheet of plywood over your existing floor, walk on it and see what happens? Maybe worth a try?

[tanneja]

@SimonD do you think I would be any better off with the felt back 18mm TG ply that I can see online?  Unsure if it would be of any assistance to squeaks.

 

http://www.provincialfloors.co.uk/hushply28.html

 

Part of me isn't convinced by TG for squeaks in these large sheet material applications, where some minute deflection is easy to imagine.  I am guessing not having TG, instead a 2mm gap between sheets, and mechanically fixing would be insufficient rigidity from the lack of interlocking.  Just feels like then I could remove any TG noise.

[LA3222]

Would the best starting point not be to smash a load of space floor screws in at 100 or 150 centres all along the joists? Cheaper and less invasive than ripping the floor up. If that doesn't work then escalate the job.

 

Those screws are very good at pulling things tight, a shit load of them should do the trick.

 

If your floor deck has been glued down it is going to be one hell of a job to get it up. What state will the top of the joists be in once it has been ripped up?

Edited March 1, 2021 by LA3222

[Onoff]

23 minutes ago, LA3222 said:

space floor screws

 

I presume you mean Spax?

 

23 minutes ago, LA3222 said:

a shit load

 

I presume you mean "many"?

 

?

[TonyT]

3 hours ago, TonyT said:

If you did decide go down the removal route and remove the 18mm chipboard  would 22mm chipboard be bettter due to the tongue and groove (T&G) rather than butting 22mm plywood?

you would also have to add additional noggins under the ply to catch each edge as it’s not T&G, so a lot more work.

 

are you able to post some pictures of the joist installation, as this is probably the problem area, as most joiners can lay chipboard flooring and have been doing so for decades ,but not engineered joists

Edit-didn’t even know plywood came in 8x2 sheets that were T&G. Thought it was only in sheet 8x4 and larger sheets!

 

every days a schools day!

[LA3222]

48 minutes ago, Onoff said:

 

I presume you mean Spax?

Yes indeed?

 

48 minutes ago, Onoff said:

I presume you mean "many"?

 

?

Nah, I definitely meant a shit load??

 

You have, 'more', 'many', 'lots' and then there is 'shit loads'...its alot??

[SimonD]

35 minutes ago, TonyT said:

Edit-didn’t even know plywood came in 8x2 sheets that were T&G. Thought it was only in sheet 8x4 and larger sheets!

 

every days a schools day!

 

Yeah, usually its TG2 for the large 8 x 4 and TG4 for the 8 x 2.

[SimonD]

2 hours ago, tanneja said:

@SimonD do you think I would be any better off with the felt back 18mm TG ply that I can see online?  Unsure if it would be of any assistance to squeaks.

 

http://www.provincialfloors.co.uk/hushply28.html

 

Part of me isn't convinced by TG for squeaks in these large sheet material applications, where some minute deflection is easy to imagine.  I am guessing not having TG, instead a 2mm gap between sheets, and mechanically fixing would be insufficient rigidity from the lack of interlocking.  Just feels like then I could remove any TG noise.

 

I've never used a product like the one you've linked above which looks more like an acoustic product designed to reduce impact noise through intermediate floors. How this might work to get rid of squeeking noises I have no idea I'm afraid.

 

TG floors will provide an excellent floor free of squeaks.

 

In your current situation, as previously suggested you've already added fixings, I guess at minimum 150mm intervals around the edges and 300mm in between but even better if it's 'shit loads' ?. You've also added noggings and you've checked as best as you can to see if there are any obvious gaps between joists and subfloor.

 

The next options really are to either add a floating floor on top of the existing installation and see if that works, or take up the existing chipboard, check joist installation and then re-install an alternative subfloor, probably plywood to see if this rectifies things.

 

I'd say that in the first instance it might be worth laying a large 8 x 4 sheet of plywood on top of the existing floor in the area you've gots squeaks to see if this helps. If this works you can then proceed with installing a floating floor otherwise do the drastic.

 

It's really difficult to say exactly what would work without seeing it all in situ

 

 

 

 

 

 

[tanneja]

I thought I would cap off this thread to say we replaced the floor with 25mm ply and it is now entirely silent.