Under floor heating - what’s the minimum height you lose

[Phooey]

Just pondering… if doing a complete downstairs remodel and already needing to re-site boiler and new pipe work (current system leaking somewhere - copper pipes in concrete floor), is it worth thinking about UFH? I’m curious to what it entails and what sort of room height loss you need to account for? Would also be interested in costs for circa 1000sq/ft of downstairs floor area. Thanks

[Fatboy]

https://www.polypipeufh.com/underfloor-heating-pro...

Used them myself - you would only lose about 22mm of height...

[oobie38]

depends largely on what sort of a floor you currently have, and whether it's insulated.

[Phooey]

Thanks for replies. Current floor is concrete, mid-seventies house, not sure if it’s insulated or not.

Whichever way I go my main concern is leaks. Currently got solid wood flooring and tiles to ground floor and a combi-boiler needing topping up daily because it’s losing pressure.

[RATATTAK]

Phooey said:

Thanks for replies. Current floor is concrete, mid-seventies house, not sure if it’s insulated or not.

Mid seventies so extremely probable there is no floor insulation.

[Semmelweiss]

I've got the polypipe system. 85sqm and it added about 24mm.

It wasn't cheap, and when including the cost of the Amtico, ply, self-levelling, labour, it worked out at approx £95 per sqm. 4 zones, 12 valve manifold.

[Phooey]

Thanks again. I never really took into account possibly needing to insulate the floor too! So, worst case scenario - floor insulation + UFH + floor covering (ceramic tile or carpet) - what type of height loss should I expect? I've got a feeling it's not going to work..

[RATATTAK]

Phooey said:

Thanks again. I never really took into account possibly needing to insulate the floor too! So, worst case scenario - floor insulation + UFH + floor covering (ceramic tile or carpet) - what type of height loss should I expect? I've got a feeling it's not going to work..

Insulation min. 50mm but should be by calculation in accordance with Building Regs.
Fibre reinforced sand/cement screed min. 50mm but preferably 75mm

[redexstyle]

We've just had underfloor heating fitted downstairs in our new home.

We didn't lose any height as we have a 1930's semi built with suspended floors. Old floorboards came up, 50mm insulation boards were fitted in between the joists, spreader plates and pipes fitted and then new 18mm floorboards so we're back upto the original level.

I know it doesn't help in terms of a concrete floor but hopefully it gives some help.

[CharlesElliott]

Phooey said:

Thanks for replies. Current floor is concrete, mid-seventies house, not sure if it’s insulated or not.

Whichever way I go my main concern is leaks. Currently got solid wood flooring and tiles to ground floor and a combi-boiler needing topping up daily because it’s losing pressure.

The UFH pipe is one continuous run with no joins, so - assuming it isn't damaged - there isn't really any chance of a leak.

[Kurtville]

RATATTAK said:

Phooey said:

Thanks again. I never really took into account possibly needing to insulate the floor too! So, worst case scenario - floor insulation + UFH + floor covering (ceramic tile or carpet) - what type of height loss should I expect? I've got a feeling it's not going to work..

Insulation min. 50mm but should be by calculation in accordance with Building Regs.
Fibre reinforced sand/cement screed min. 50mm but preferably 75mm

In an ideal world the above but being practical ... We have a similar 70's house with concrete ground floor presumed without insulation and same problem with unprotected ch pipes in concrete. We have done the whole of the ground floor ourselves using the Wunda 20mm board system direct on to the concrete. We have had this down three year now and very happy with the results and the heating provided is much better and more evenly spread than the previous piped system (No more hugging the radiators). Yes I am sure it would be better with insulation underneath but based on our experience I wouldn't hesitate to recommend going ahead.

[caziques]

Have a look at https://www.jk-gb.com/

Basically grooving an existing floor. JK can only do screed floors, not concrete.

I have done concrete grooving in my own house (and a couple of other jobs). It's quite an effort but worth it in the end.

If the slab doesn't have any insulation, keep 600mm away from all outside walls, there is no real loss of energy downwards (nowhere for it to go).

Let me know if you need any more info.

[Gtom]

https://www.nu-heat.co.uk/

A friend of mine has done several installs with this system and it works. Overlay on the existing floor and then screed over.

[Phooey]

Thanks again for replies. Lots to consider if spending this amount of money on something that I really don't know if will be better than sticking with radiators or not. A chap I spoke to yesterday said he would stick with rads unless "doing it properly", which in a 70s house with no floor insulation is very difficult.

Kurtville said:

In an ideal world the above but being practical ... We have a similar 70's house with concrete ground floor presumed without insulation and same problem with unprotected ch pipes in concrete. We have done the whole of the ground floor ourselves using the Wunda 20mm board system direct on to the concrete. We have had this down three year now and very happy with the results and the heating provided is much better and more evenly spread than the previous piped system (No more hugging the radiators). Yes I am sure it would be better with insulation underneath but based on our experience I wouldn't hesitate to recommend going ahead.

Thanks, that's good to hear from someone in a similar situation. Our house is naturally cold anyway, speed of heat loss is ridiculous so we need to do a combination of things along the lines of retrofitting the whole house.

caziques said:

Have a look at https://www.jk-gb.com/

Basically grooving an existing floor. JK can only do screed floors, not concrete.

I have done concrete grooving in my own house (and a couple of other jobs). It's quite an effort but worth it in the end.

If the slab doesn't have any insulation, keep 600mm away from all outside walls, there is no real loss of energy downwards (nowhere for it to go).

Let me know if you need any more info.

Thanks, I'll take a look..

Gtom said:

https://www.nu-heat.co.uk/

A friend of mine has done several installs with this system and it works. Overlay on the existing floor and then screed over.

Thanks, perhaps I ought to give them a call

[WyrleyD]

We used this https://baseufh.co.uk/system/12-ultra-low-panel-sy... We did all the downstairs after knocking down two walls and extending out to the rear, after knocking down the walls we were left with three different levels so used self levelling compound throughout. As it was virtually all the downstairs apart from the lobby raising the floor a little wasn't an issue. The UFH has been in 3 years this year and has been great.

[TonyRPH]

A neighbours house is built over a garage.

He installed underfloor heating (without insulation) but the house was never really warm.

This winter, he installed 100mm PIR to the underside of his garage roof, and has already seen a 20% cost saving in heating bills.

If the floor slab is cold, it's just going to soak the heat away without any insulation, as I believe it will try to become a thermal mass - and if there isn't enough heat to actually heat the mass...

Even our previous flat (built in 1960) with electric underfloor heating had a layer of insulation on top of the slab.