Concrete floor question..used search and now more confused..

[Darren1234]

I'm intending to lay a concrete floor with water UFH, but I'm reading conflicting advice when it comes to the order??

To me the logical order would be ...


70mm screed with pipe work in and either mesh or fibre reinforce
100mm insulation foam
100mm Slab concrete
DPM
Binding 10mm
Hardcore

This would mean you're just heating the screed layer?.

I've also found however (from the internet and within this forum) the following order suggested...

70mm Screed with pipe work in and either mesh or fibre reinforce.
100mm Slab concrete
100mm Insulation foam
DPM
Binding 10mm
Hardcore

Doesn't this method obviously mean you're heating the large slab too? How would you clip the pipework with this method? drilling and rawlpluggin the slab?


Is either method acceptable? does either method do the job as effectively as the other ?
Or is it a matter of whether there is UFH in the job at all alters which one you use?

Thanks
Daz

 

[mnemonix]

With UFH heating it is normal to insulate above the slab, under the screed so you are not having to heat the slab too, as you say. For non-UFH floors the insulation is laid below the slab.

The practical difference is the time taken to heat the floor up to temperature and for it to cool when the heating is switched off. Where a building is constantly occupied having more thermal mass 'inside' the insulation is desirable to maintain a stable temperature. For intermittant occupancy it is desirable for the bulding to heat up quickly when you want to use it, so ultimately there is no right or wrong answer - you design your construction to suit the use.

 

[mointainwalker]

How would you clip the pipework with this method

Wire it to the mesh.

 

[Norcon]

Building regs here in NI put the insulation over the slab in all cases which is the best way to do it imo.

 

[^woody^]

Insulating under the slab will give advantages in terms of using the thermal mass of the concrete to aid heating and cooling, so its not always better to insulate above it.

But with underfloor heating, the insulation should be above the slab as otherwise there will be impractical response rates for the heating, and more heat wastage/power usage