Thermal insulation between occupied floors

[Crowbar hero]

Hiya

I'm trying to figure out the depth/quantity/quality of thermal insulation required between occupied floors. I've tried searching for guidance in the building regs, but they only seem to want to talk about acoustic insulation between internal floors.

 

Background:

 

I'm planning the first floor makeup of my extension, which has 200mm joists (installed already). I'm having a wet UFH system up and down, the upper system is based on a Pug mix/biscuit mix basis, which needs a firm base and insulation to sit on.  I've been sent 60mm staples, which I feel are a bit long as I was initially planning on 25mm PIR board insulation, which when added to 12mm plywood and 38mm supporting batten (below the perimeter of the ply) sits just above the 50mm zone on the centre of the joist that I can drill for services.  The floor below is the kitchen diner, so will be heated.

 

Is the 25mm going to be enough to satisfy whatever regulation it is I can't find?  Can anyone steer me towards the correct regs if they do exist?

 

cheers

 

G

 

[ADLIan]

Under 2021 Appr Doc L there is a requirement for thermal insulation in intermediate heated floors - not onerous however. Prior to this no thermal requirement but acoustic requirement of 100mm mineral wool.

[ETC]

Why do you want to thermally insulate between two heated spaces?

[ADLIan]

Different heating zones?

[Crowbar hero]

1 hour ago, ADLIan said:

Under 2021 Appr Doc L there is a requirement for thermal insulation in intermediate heated floors - not onerous however. Prior to this no thermal requirement but acoustic requirement of 100mm mineral wool.

Finally found it:

 

section 6.28:

Quote

6.28 The intermediate floor should have a separating layer of system thermal insulation with thermal resistance of one of the following.

a. As in paragraph 6.26.

b. As specified in BS EN 1264-4, in one of the following scenarios.

i. For electric systems, of not less than 0.5 (m² .K)/W.

ii. For wet systems, of not less than 0.75 (m² .K)/W.

 

So for a wet system, 0.75m²K/W is acheivable with less than 25mm of PIR, as this has an R value of 1.15m²K/W (according to celotex).

 

thanks

 

 

[ADLIan]

Check which version of the Regs apply. Also Wales (your location?) may be different to England 

[Crowbar hero]

59 minutes ago, ADLIan said:

Check which version of the Regs apply. Also Wales (your location?) may be different to England 

aha.

 

Section 6.32 for wales 🙃

 

 

[Nickfromwales]

Aluminium spreader plates for me, just so quick and simple. Great results every time.

[Crowbar hero]

On 12/08/2022 at 22:24, Nickfromwales said:

Aluminium spreader plates for me, just so quick and simple. Great results every time.

Sadly not an option for me, as I've uneven joist distances in the old part of the house, and they're not recommended for heat pumps, which may be an issue in the future.

 

I'd much prefer the quick and simple approach though, this is looking like a proper headache.

[davejura]

Crowbar Hero, just looking at your floor make up. We are doing the same, having a wet UF system on the first floor which will be the living area. I have just gone for 100mm PIR which will be supported by battens (no ply as the 100mm should be strong enough to take the pug mix and pipes). I haven't allowed for any acoustic insulation though, as thought that between the 100mm PIR and the 30mm pug mix, that should do the trick. Any thoughts anyone?

[markc]

30mm with pipes straight on top of PIR … I reckon you are in for an uneven floor with lots of cracks. Or am I missing something here?

Edited August 15, 2022 by markc

[davejura]

I'm now looking at battening the chipboard flooring, laying the UF heating pipes in screed and laying 20mm engineered flooring directly above. Would just have acoustic insulation below the chipboard between the joists. This is on the first floor (living area). Would this meet building regs in Scotland or do I need 25mm PIR board as well?

[Crowbar hero]

On 22/08/2022 at 18:24, davejura said:

I'm now looking at battening the chipboard flooring, laying the UF heating pipes in screed and laying 20mm engineered flooring directly above. Would just have acoustic insulation below the chipboard between the joists. This is on the first floor (living area). Would this meet building regs in Scotland or do I need 25mm PIR board as well?

 

Is the floor below inhabited? Part of the same dwelling? The requirement for thermal insulation between floors is less vigorous as per my earlier post - check your regs, but I figured that 25mm PIR is enough to meet the 0.75m²K/W required by the Welsh BC.

Half the challenge is in finding the relevant bit in the regs.

Edited August 23, 2022 by Crowbar hero

[Crowbar hero]

On 15/08/2022 at 10:06, markc said:

30mm with pipes straight on top of PIR … I reckon you are in for an uneven floor with lots of cracks. Or am I missing something here?

 

Pipes onto PIR is recommended by the supplier - bear in mind there will be the structural floor going on top of this lot, I'm not sure how this setup would make it uneven..?

[markc]

7 hours ago, Crowbar hero said:

 

Pipes onto PIR is recommended by the supplier - bear in mind there will be the structural floor going on top of this lot, I'm not sure how this setup would make it uneven..?

Sorry my mistake, I was using my phone and didn’t see the the sketch with 22mm decking, got it into my head that to save space and floor build up you were using the pug mix like a screed.

[davejura]

I'm now going with the Fastwarm Duo panels. They gave me a really good price on them to go with the UF heating, so is going to make life a lot simpler!

[embra]

Interested to know how you got on with Fastwarm Duo panels? What was the final floor build up that you went for? Did you keep the 22 mm decking and float on top of the UFH panels? What output per m2 did you need?

 

Also looking at the Fastwarm system and interested in others feedback!