Worth Taking up Chipboard Panels To Make Improvements While the Carpets are off?

[endecotp]

I've taken the floor up and was met with 80mm of rigid insulation panel (Kingspan), so it's a floating floor, no wonder it creaks so much.

A floating floor shouldn’t creak, if done properly with a flat base below the insulation boards.

Is this the ground floor? You mentioned the option of taking down the ceiling instead, which suggests that it is the first floor, but it would be odd to insulate the first floor like this.

The main surprise is that under the kingspan are heating pipes, and the void for them is made by putting 50mm Kingspan on either side of each pipe, putting a slim piece of wood across them, then putting an upper piece of Kingspan on top. Photo attached.

Hot unlagged pipes below the insulation is ridiculous…. and it doesn’t surprise me that it creaks.

I’ve built a floating floor in my hall, which has a lot of pipes. I would put a continuous layer of insulation boards at the bottom, then pipes on top; where there are no pipes, put down a second layer of insulation boards. To avoid expansion/constraction noises, lag the CH pipes with felt. Then fill the rest of the space around the pipes with rockwool or similar. T&G OSB on top. Of course the question is, what is the un-supported (i.e. less-supported) span across the pipes, and what can you get away with before it starts creaking….

But your challenge is what you can do now, starting with what you already have.

2. Are cables in this kind of ceiling likely to be in conduits only? Any issue with adding cabling without adding the conduit

Conduit is not required, but cables under insulation (in conduit or not) need to account for it so they don’t overheat. Probably not a problem for lighting but other circuits will likely need to go up a size.

 

[JohnD]

I have some of the white expanding foam (can't see any mention of fire-resistance), any good or is the main point here the fire resistance?

Fires are a lot rarer than draughts, but I was doing a lot of doorways and floors so I bought the pink. It can also hold plasterboard ceiling firm to prevent or repair cracks.

I understand the colour is so inspectors can see which grade has been used.

If you are doing a lot, a foam gun gives better control, but also buy a can of gun cleaner.

 

[JimbobTheSailor]

Chipboard and ply aren’t the only options; you could also consider 18mm OSB.

Thanks, I'll look into the relative benefits of OSB vs plywood. Any reason not to use 22mm OSB instead of 18mm? That'll help maintain current floor height.

Is this the ground floor?

The ground floor's ceiling. The first floor's ceiling is wooden joists with chipboard directly on top, but the composition of the ground floor's ceiling is, in vertical order:

22 mm T&G chipboard.
80 mm Kingspan rigid foil-backed PIR insulation.
50 mm PIR insulation supporting the insulation above it to create a void for hot water & heating pipes to go. The void is spanned with thin strips of wood forced into the insulation so the 2 layers of insulation are in contact.
70mm approx (maybe there's a standard thickness? of concrete planks supported by 2 steel I-beams 1/3 and 2/3 of the way along the house.
100 - 120 mm void where 2 layers of wooden joists/battens are hung across each other. One batten is attached to the concrete plank, then a batten is attached below that at a right angle to attach the ceiling panel.
12 mm plasterboard ceiling.

But your challenge is what you can do now, starting with what you already have.

Indeed. I'm prepared to make a lot of changes to make it work but I think I'd stop at screeding.
The floor panels sit atop 130mm of rigid insulation panels, which are not very carefully laid out, supported, or made level.
Do you know of a way to affix an OSB / ply floor panel in this arrangement?

 

[endecotp]

Thanks, I'll look into the relative benefits of OSB vs plywood. Any reason not to use 22mm OSB instead of 18mm? That'll will help maintain current floor height.

I don’t know if you can get 22mm T&G OSB.

Ground floor's ceiling.

Why is there so much insulation between floors???

Is the “ground” floor actually an unheated garage or cellar?

 

[JimbobTheSailor]

Why is there so much insulation between floors???
Is the “ground” floor actually an unheated garage or cellar?

I wish I could ask the builders that myself!
The ground floor's the kitchen and living room. Hopefully that's generously insulated underneath too but I'm not yet brave enough to drill through the screed on the ground floor to confirm. Ground floor is quite cool in summer because it doesn't get much sun. The upper floors get pretty sweltering, although I guess it's not so much to do with all that insulation.

The bright side is this floor construction reduces some of my tasks, but I'm still at a loss as to the way the floor should have been constructed correctly to avoid the panels creaking.

 

[endecotp]

I'm still at a loss as to the way the floor should have been constructed correctly to avoid the panels creaking.

Don’t have unsupported PIR boards. Put the pipes above them.

If you must have a large pipe channel below the insulation boards, the boards above need much more support e.g. a layer wood.

 

[cdbe]

That's horrendous. Maybe some timber joists would be better - notched/spaced around the pipes, 400mm centres.

I'd still reuse the chipboard - as for those banging holes through 22mm flooring grade chipboard with their bed legs (I can understand council house Weetabix chipboard) - you must be having more fun in the bedroom than me!

 

[JimbobTheSailor]

No chance of moving the pipes, and I think making joists is a step beyond what I have time for, since it would require hundreds of precise notches in the joists and loads of PIR cutting to fit between them.

The only half-solution that my bodger brain can come up with is to place 4mm ply boards above the first 50mm layer of PIR which flanks the heating pipes, then the 80mm PIR on that and 18mm OSB on top. That'll improve the stiffness of the "bridge" over pipes and matches the current 22 mm total height of wood.

Not ideal because nothing will be levelled or screwed down, but if I'm careful to keep seams of each layer from overlapping, it should flex less than now so creaking might be reduced.

 

[endecotp]

place 4mm ply boards above the first 50mm layer of PIR which flanks the heating pipes, then the 80mm PIR on that and 18mm OSB on top. That'll improve the stiffness of the "bridge" over pipes and matches the current 22 mm total height of wood.

I think that would be a good solution - if it were more than 4mm. It’s hard to guess what is really needed though.