Floor insulation: build up

[bmj1]

Our GF build up is:

• Beam & block
• DPM
• PIR insulation
• Liquid screed
• Floor finish

 

Should the PIR insulation layer be foil or tissued faced? One-side or both sides ?

 

Or should we be putting a plastic membrane between the PIR and liquid screed, in which case tissue facing is fine ?

 

Thank you in advance.

[nod]

Membrane on your BB taped to your dpc Then insulation Foil both sides 

Joints taped Then another membrane Then pipes 

[bmj1]

I'm a bit confused by the K103 product:

 

K103 insulation is designed for floor insulation in floor buildups. You can install K103 phenolic foam boards in block and beam, solid concrete, suspended ground floors and timber floors. The insulating core is surrounded by glass tissue facings.

 

Why do they surround it by glass tissue facings ?

[Chanmenie]

1 hour ago, bmj1 said:

Our GF build up is:

• Beam & block
• DPM
• PIR insulation
• Liquid screed
• Floor finish

 

Should the PIR insulation layer be foil or tissued faced? One-side or both sides ?

 

Or should we be putting a plastic membrane between the PIR and liquid screed, in which case tissue facing is fine ?

 

Thank you in advance.

Do you have bad ground (clay) ? 

if not why have block and beam, ground bearing slab is more efficient.

I put a DPM under the PIR and a slip membrane ontop of the PIR, but I had concrete not screed. The slip membrane prevents the concrete from damaging the foil face of the PIR, I assume screed would do the same 

[bmj1]

1 minute ago, Chanmenie said:

Do you have bad ground (clay) ? 

if not why have block and beam, ground bearing slab is more efficient.

I put a DPM under the PIR and a slip membrane ontop of the PIR, but I had concrete not screed. The slip membrane prevents the concrete from damaging the foil face of the PIR, I assume screed would do the same 

 

Yes, London Clay

[Chanmenie]

25 minutes ago, bmj1 said:

 

Yes, London Clay

Yeah that’s not great hence the BnB 

But yes I’m pretty sure you need a slip membrane, 500g polythene 

much thinner than DPM.

Celotex or Mannok is usually much cheaper than Kingspan, how thick can you go with the PIR 

Edited June 13, 2023 by Chanmenie

[bmj1]

1 hour ago, Chanmenie said:

Yeah that’s not great hence the BnB 

But yes I’m pretty sure you need a slip membrane, 500g polythene 

much thinner than DPM.

Celotex or Mannok is usually much cheaper than Kingspan, how thick can you go with the PIR 

 

Thanks, makes sense. DPM below and above then.

 

I've grabbed some 75mm Kooltherm from Seconds and Co.. (£400 / pallet of 20 sheets).

 

Can't go wrong at that price.

 

My max was 90mm, but that was pushing it on tolerance. This is much more comfortable.

 

Gets us a floor u-value of 0.157, which we'll compensate for with solar PV.

 

I'd rather have the extra ceiling height than a slightly more energy efficient house.

Edited June 13, 2023 by bmj1

[Dave Jones]

shame the correct flooring detail below FFL is often overlooked. see a lot of threads here with same. A simple thing to get right at the time, very hard after.

 

Yet another basic building function architects are clueless on.