Advice wanted for underfloor heating construction
Posted: Tue Jul 18, 2023 12:34 pm
Hi,
I have built an office in the garden and I am looking for advice on how best to heat it in the winter. I'm leaning towards electric UFH but maybe this isn't right. If UFH is the right choice I'm not sure on if my proposed construction would work (and I can't easily find info on this online).
There is a concrete slab base with insulation underneath, and I have 70mm - 75mm to the final floor height.
I was looking at levelling the slab base (it's up to 10mm low in a couple of places but generally pretty flat) putting 50mm XPS insulation down, an electric heating mat on top, with floating engineered or laminate floor to finish.
The first question - is electric underfloor heating so slow to heat up that I'm better off with wall mounted IR heaters or something else? I'll be using the office for 8 hours a day, 5 days a week so super-reactive heating isn't really required, and I don't mind it a bit chilly in winter as long as it's not totally freezing. The office itself is fairly well insulated (see below).
My second question is can I put an electric mat straight on top of 50mm insulation, or do I have to use thinner insulation board with a screed on top? I'd prefer the first option because it's both easier to do (by myself), and more importantly would push more of the heat into the room rather than heating the slab below.
If it helps the office construction is:
8m x 4m external size
7.6m x 3.6m internal size
Built on concrete slab 170mm thick (reinforced), with 200mm XPS insulation underneath.
Wall construction: plinth of 3 courses engineering brick (225mm high), then 100mm timber frame construction with glasswool insulation between and 80mm wood fibre and render externally, and 25mm PIR + plasterboard internally.
Roof construction: 125mm rafters with glasswool between and 25mm PIR + plasterboard internally, tiled externally
I have built an office in the garden and I am looking for advice on how best to heat it in the winter. I'm leaning towards electric UFH but maybe this isn't right. If UFH is the right choice I'm not sure on if my proposed construction would work (and I can't easily find info on this online).
There is a concrete slab base with insulation underneath, and I have 70mm - 75mm to the final floor height.
I was looking at levelling the slab base (it's up to 10mm low in a couple of places but generally pretty flat) putting 50mm XPS insulation down, an electric heating mat on top, with floating engineered or laminate floor to finish.
The first question - is electric underfloor heating so slow to heat up that I'm better off with wall mounted IR heaters or something else? I'll be using the office for 8 hours a day, 5 days a week so super-reactive heating isn't really required, and I don't mind it a bit chilly in winter as long as it's not totally freezing. The office itself is fairly well insulated (see below).
My second question is can I put an electric mat straight on top of 50mm insulation, or do I have to use thinner insulation board with a screed on top? I'd prefer the first option because it's both easier to do (by myself), and more importantly would push more of the heat into the room rather than heating the slab below.
If it helps the office construction is:
8m x 4m external size
7.6m x 3.6m internal size
Built on concrete slab 170mm thick (reinforced), with 200mm XPS insulation underneath.
Wall construction: plinth of 3 courses engineering brick (225mm high), then 100mm timber frame construction with glasswool insulation between and 80mm wood fibre and render externally, and 25mm PIR + plasterboard internally.
Roof construction: 125mm rafters with glasswool between and 25mm PIR + plasterboard internally, tiled externally