Kooltherm K103 - underfloor heating clips ?

[bmj1]

Hi wise people,

 

Was planning to do underfloor heating with liquid screed over kooltherm phenolic insulation.

 

Kingspan advise that this insulation should not get wet, so plastic sheet above.

 

So how do we do the clips for underfloor heating without piercing the insulation ?

[Thorfun]

8 minutes ago, bmj1 said:

Hi wise people,

 

Was planning to do underfloor heating with liquid screed over kooltherm phenolic insulation.

 

Kingspan advise that this insulation should not get wet, so plastic sheet above.

 

So how do we do the clips for underfloor heating without piercing the insulation ?

you can't! but don't worry the liquid screed won't get through the staple holes. here's a photos of ours

 

 

just staple through the dpm and in to the insulation. so simple I did all ours myself with my wife on the stapler most of the time.

[saveasteading]

You just pierce the membrane and insulation and don't worry about it.

Pir doesn't really get wet. The membrane is to stop the wet screed flowing between joints and floating the pir.

 

Edited June 14, 2023 by saveasteading

[Canski]

Can you not also glue the dpm to the insulation and use self adhesive rails for the pipe work ?

[bmj1]

6 hours ago, saveasteading said:

You just pierce the membrane and insulation and don't worry about it.

Pir doesn't really get wet. The membrane is to stop the wet screed flowing between joints and floating the pir.

 

 

Sure. Only thing is it isn't PIR, it's the phenolic product. K103

 

So not quite sure how it behaves !

[Jilly]

We used it as above. Works fine, am really pleased with the floor's performance. 

[bmj1]

Just now, Jilly said:

We used it as above. Works fine, am really pleased with the floor's performance. 

 

Ok fab. Out of curiosity, how thick did you go ?

[Jilly]

We could only get 100mm in, which is insufficient really and why I chose to use it, hoping it would have better performance than 100mm PIR (or EPS). 

 

Incidentally, I also researched a lot before coming to a view, and decided to use slate tiles, rather than engineered wood to improve the heat transfer.  I even chanced not using decoupling mats, as the plumber thought it would reduce the efficiency of the floor, which made sense to me. We used good quality expansion joints at the door thresholds and don't heat the floor over 35 degrees and I was ultra cautious about turning it on at all in the beginning. 

Edited June 14, 2023 by Jilly

[saveasteading]

3 minutes ago, Jilly said:

chanced not using decoupling mats,

Yes...I couldn't find  figures so we chanced it too.

 

A good comparison may be carpet underlay.  Unless specially made for ufh, it is a good insulator.

 

[bmj1]

34 minutes ago, Jilly said:

We could only get 100mm in, which is insufficient really and why I chose to use it, hoping it would have better performance than 100mm PIR (or EPS). 

 

Incidentally, I also researched a lot before coming to a view, and decided to use slate tiles, rather than engineered wood to improve the heat transfer.  I even chanced not using decoupling mats, as the plumber thought it would reduce the efficiency of the floor, which made sense to me. We used good quality expansion joints at the door thresholds and don't heat the floor over 35 degrees and I was ultra cautious about turning it on at all in the beginning. 

 

Insufficient in terms of sap calcs? Or the house feels cold/is costly to heat? Are you using a heat pump ?

[Thorfun]

4 hours ago, Canski said:

Can you not also glue the dpm to the insulation and use self adhesive rails for the pipe work ?

ufh click tracks are expensive, staples are cheap! 😉 

[Jilly]

48 minutes ago, bmj1 said:

 

Insufficient in terms of sap calcs? Or the house feels cold/is costly to heat? Are you using a heat pump ?

It's a conversion, so no SAP calcs, just @SteamyTea's advice that you need loads more insulation than you think under ufh.

No, I think it's worked, the hose is warm and pretty cheap to heat. On LPG at the moment but 'heat pump ready'. 

 

I think the UFH egg boxes might reduce efficiency too, so we used staples.

[bmj1]

49 minutes ago, Jilly said:

It's a conversion, so no SAP calcs, just @SteamyTea's advice that you need loads more insulation than you think under ufh.

No, I think it's worked, the hose is warm and pretty cheap to heat. On LPG at the moment but 'heat pump ready'. 

 

I think the UFH egg boxes might reduce efficiency too, so we used staples.

 

What screed did you use? I'm planning 40mm liquid screed to maximise heat transfer

[Iceverge]

10 hours ago, bmj1 said:

kooltherm phenolic insulation.

 

How tight are you for floor buildup space ?

 

The sums almost never make sense Vs using PIR at a fraction of the price and doubling up insulation elsewhere instead for less money overall. 

 

 

[bmj1]

24 minutes ago, Iceverge said:

 

How tight are you for floor buildup space ?

 

The sums almost never make sense Vs using PIR at a fraction of the price and doubling up insulation elsewhere instead for less money overall. 

 

 

 

Very tight. ~120mm total for insulation + screed (to include underfloor heating)... I managed to pick up 75mm phenolic for £20/sheet from Secondsandco (link), so I think that's the best result I can hope for given the situation.

[Nickfromwales]

40 minutes ago, bmj1 said:

 

What screed did you use? I'm planning 40mm liquid screed to maximise heat transfer

This will give you almost "on - off" heating characteristics. Is that a choice, or a constraint?

[Nickfromwales]

8 minutes ago, bmj1 said:

 

Very tight. ~120mm total for insulation + screed (to include underfloor heating)... I managed to pick up 75mm phenolic for £20/sheet from Secondsandco (link), so I think that's the best result I can hope for given the situation.

Ah, OK  

[bmj1]

6 minutes ago, Nickfromwales said:

This will give you almost "on - off" heating characteristics. Is that a choice, or a constraint?

 

A constraint. But I'm ok with it. I'm planning to have each room zoned with heatmiser.

 

Tbh - instant response sounds good to me. I'm not sure I understand why we would want to wait an hour to feel the benefit of the heating ?

[bmj1]

11 hours ago, saveasteading said:

You just pierce the membrane and insulation and don't worry about it.

Pir doesn't really get wet. The membrane is to stop the wet screed flowing between joints and floating the pir.

 

 

Awesome, thank you !