underfloor heating retrofit

David09

I've a bungalow that was constructed in the 1950s that had timber suspended ground floors. I'm renovating the house and tore them out in the process. The plan is to lay dpc, insulation and a concrete floor with ufh.

The question is what would be the necessary thickness of floor insulation required to beneath the concrete if I'm to run ufh? Would 100mm be sufficient?

Secondly, does ufh perform well when powered by a condensing oil fired boiler or would I be better off sticking to radiators?

dathi

no 100mm will not be sufficient for under floor heating, the building regs part L say you need a u value of 0.15 for underfloor. you need to get someone to work out the specific u value for your floor, as they need the size,shape, and external wall lengths, of your floor to work out the u value figure for various thicknesses of insulation used.

BryanF

you'd want to carefully consider the building fabric particularly junctions of walls/doors and floors - even in relatively new homes the lack of adequate insulation has made many installed UFH systems inefficient and costly to run

David09

I bought 100mm thick sheets of Quinn therm insulation. If that's not adequate, would I be better off buying more, 50mm slabs and laying them on top of each other to bring the overall level to 150mm?

@ Bryan, yes, that was mentioned to me about paying extra attention to edges of floor slab.

vinnie13

personally i would stay away from under floor heait really efficenttnig,it only works it you keep the house locked up 24/7 and is very well insulated top to bottom.if you like opening doors and windows this wont work at all..can be more expensive to heat and take longer..