Perimeter to floor ratio / floor construction

[garyo]

The Jablite site says I should be using internal dimensions, so that would make my calcs 1.520+3.940+.572 / 5.98 = 1.00 (omitting the non exposed walls)

 

[mikric]

85mm cellotex/kingspan will give a u-value of 0.21W/m2k which is above what you need to achieve based on your calcs

 

[Chukka63]

Odd how things appear to differ from post code.

We've had to put 100mm celotex under floors for yonks here.25mm upstands.The DPM has to go OVER the insulation.It then has to be bedded into the DPC joint.If its not possible at time of laying the slab we use wider DPC to fold down the wall to overlap the DPM.

If using Jablite the thickness will need to be increased.

 

[garyo]

Thanks guys.

I'll be getting building control to give the plans a once over so that, hopefully, I shouldn't get caught out by local anomolies. I'd like to over do the insulation if possible, but it's such a small build I think that'll mostly be determined by what thickness left overs I can get my hands on.

 

[jeds]

Odd how things appear to differ from post code.

We've had to put 100mm celotex under floors for yonks here.25mm upstands.The DPM has to go OVER the insulation.It then has to be bedded into the DPC joint.If its not possible at time of laying the slab we use wider DPC to fold down the wall to overlap the DPM.

If using Jablite the thickness will need to be increased.

There's no postcode difference. Thermal insulation is a National standard. What differs is the understanding of building inspectors. One wants one thing, another wants another. My advice is tell them what they want to hear and then do it the correct way.