Streetfield

[Streetfield]

Hi, our predictive SAP for the new self build says we need to use 125mm thick Kingspan k103 insulation on top of the ground  concrete slab (prior to UFH and screed). It appears that 125mm is not a standard size and is subject to min order levels. Can anyone help/advise please?  

[Dave Jones]

use a sheet of 100 and a sheet of 25. both all merchants stock.

[nod]

Go to 150 + 75 screed = 225 = 1 block 

[Conor]

As nod says, put in 150mm and thinner screed if needed. 150mm is really the min you want really.

[Streetfield]

Hi Conor, we only have c.200mm to play with for insulation and screed. Not sure 50mm liquid screed with UFH will be enough. This sort of issue is one where some architects need to be more clued up ie energy efficiency when at design stage. Must admit I can't believe the amount of insulation going into the house per ce (and cost) whilst I appreciate it will save £ in future.

[Dave Jones]

yep architects are clueless, you could have saved money and got a much better insulation value by using 300mm of EPS instead.

[Conor]

46 minutes ago, Streetfield said:

Hi Conor, we only have c.200mm to play with for insulation and screed. Not sure 50mm liquid screed with UFH will be enough. This sort of issue is one where some architects need to be more clued up ie energy efficiency when at design stage. Must admit I can't believe the amount of insulation going into the house per ce (and cost) whilst I appreciate it will save £ in future.

No, 50mm is absolutely fine, it's what we have throughout our house. Go for 50mm + 100mm PIR + 50mm liquid screed. Well taped, gaps filled, no rocking boards.