insulation level elec underfloor heating in new extension

[burt12345]

Hi, Hope someone can help.

We've built an extension on the back of our house which we plan to fit underfloor tile electric heating, which we also want to run into two rooms in the existing house hence not choosing an in-screed system.

My problem is that if I screed the extension to the same level as the existing hall and dining rooms (70's extension no under screed insulation), then I'll need to put (by the advice of the underfloor heating company) a min 6mm of their insulation on top of the screed (the new extension will have 150mm PIR under that. The trouble is when I ordered the bifold doors this 6mm wasn't in the equation as I thought I'd go for in-screed. I can raise these door as I can shave the lintel as we used ICF blocks, but would rather not.

I've looked at alternatives, and you can get 1mm foiltec? but I'm not sure if you can lay the cables and tiles direct on top of that, and whether it will be efficient and do the job I want it to.

We chose the under tile as opposed to in screed as it will also heat up quicker - I'm guessing though if my above screed insulation isn't thick enough then we will have in effect the inscreed slower to warm up but holds it's temp longer effect?

Could someone offer some direction please.

thanks Matt

[burt12345]

Anyone? Have I posted in correct forum?

[Dave From Leeds]

I'd try re-posting it in the "Electrics" section if I were you.