Underfloor heating HELP!!

[GMajor13]

I am hoping you can help me with my underfloor heating problem.
I am currently building an extension to the rear of the property and have now decided after the floor has been prepped and signed off to try and install underfloor heating. Floor construction is MOT, sand blinding, DPM, 100mm insulation and a further layer of dpm. This leaves 100mm to reach DPC. Almost all recommendations by suppliers say that 100mm is too thick of a slab to place underfloor heating in and to reduce this to use a screed,however this means that the floor will not satisfy the required 100mm under regs. I lf I was to screed on top this would raise the floor in comparison to adjoining rooms. Help!

Has anyone any experience of laying UFH in a slab this thick and achieved decent results?
If so what effect does piercing the second layer of DPM have?
Any other suggestions on how I can still achieve UFH in my situation?
Many thanks in advance, I hope someone can help!!

 

[Chalker]

Why not use thicker insulation?

 

[GMajor13]

Why not use thicker insulation?

Does the concrete not have to be 100mm for regs?

 

[Dumbo]

I don't understand have you got insulation under the foundation slab ( oversight ) most floor build ups are slab , dpm , insulation , slip coat (thin guage membrane ) then screed . My screed at home is a pumped screed about 55mm thick most sand and cements are about 75mm .

 

[Andy Allen]

Do you mean piped ufh..?

 

[GMajor13]

I don't understand have you got insulation under the foundation slab ( oversight ) most floor build ups are slab , dpm , insulation , slip coat (thin guage membrane ) then screed . My screed at home is a pumped screed about 55mm thick most sand and cements are about 75mm .

The floor is prepped to pour the floor slab.
The build up is;
MOT
Sand blinding
DPM
100mm insulation
DPM
This now leaves 100mm (required concrete) to dpc to fill with concrete that I would like to fit wet piped UFH in.

 

[One Day]

50mm kingspan + ufh with 50mm anhydrite screed. Simple.

 

[Dumbo]

Sorry wasn't following mot as being scalpings . Just increase your insulation thickness

 

[GMajor13]

Sorry wasn't following mot as being scalpings . Just increase your insulation thickness

Thanks JCRtiling for your responses. Surely this won't work though as then I won't achieve the 100mm floor thickness BC require

 

[jobdone]

Is there not another layer of screed to go on the slab