UFH which one best for wooden and concrete floor?

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Naresh2022

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Hi All,

Need expert's ideas. I am extending the house, I would like to go with water-based under-floor heating. The total floor area is 85 sqm and going to use tiles on top of it.

I have 50% wooden sub floor (existing floor) and 50% concrete sub floor (new extension).

1. Can someone suggest which ufh is better to accomodate both floorings? because I am going to do a concrete floor next week and need to decide the height of the floor.

2. Is there any technology that covers both (wooden and concrete)floors?

3. Is this any good?
https://www.theunderfloorheatingsto...le-overlay-underfloor-heating-single-room-kit


Thanks.
NK.
 
Last edited:
You need separate zones as each will heat at different rates.

you can use spreader plates for wet underfloor heating in between joists.

it’s even possible to use screed in between joists to act as a heat sink, however that requires joists of sufficient strength to support the dead load. It’s known as a biscuit screed

https://baseufh.co.uk/system/07-biscuit-screed-underfloor-heating-system/
 
I was lucky enough to have a pretty decent concrete slab under my suspended wooden floors so I removed them, blinded the concrete with sand and leveled, tanked with thick DPC and used 200mm of Celotex to build up the height within 60mm of the concrete floor adjacent. I then tanked over the top with more DPC and had a liquid screed poured. No more creaky, draughty wooden floor! I know it sounds expensive ( I used a lot of Celotex!) but a site local to me had a huge amount of Celotex going in the skip and they were over the moon at my offer to take a load of it!
 
In your OP you say you have half wood half concrete then in your last post you've no more draughty wooden floor??

If you have the height then ideally you would use a screed with it all, do you know what's under the other slab insulation wise?
 
Madrab said:
In your OP you say you have half wood half concrete then in your last post you've no more draughty wooden floor??

If you have the height then ideally you would use a screed with it all, do you know what's under the other slab insulation wise?
Click to expand...

Are you mixing up me and the OP? My wooden floor was about 70% of the area and the other 30% was concrete. I never did like my wooden floor but my hand was forced due to the damage to it caused by the builders. The 30% concrete part was new and already had Celotex under, the old suspended floor, fortunately, was above a substantial concrete base.
 
You'll need a floor probe (or 2) for the timber floor and manufacturers will provide information about what temp it must not go above. Choose your floor covering wisely and space appropriately for MWT-AT.
 
Madrab said:
In your OP you say you have half wood half concrete then in your last post you've no more draughty wooden floor??

If you have the height then ideally you would use a screed with it all, do you know what's under the other slab insulation wise?
Click to expand...

Have half wooden subfloor (existing house) and half concrete slab (going to do, not done yet).

For the concrete slab, not decided about insulation. Will decide based on the expert's ideas.
 
upload_2022-5-10_7-24-52.png



can I use this for both wooden and concrete floors (with different zones)?

I will bring both floor levels to the same height and use those boards and on top of that just tile directly without screeding??

has anyone used those boards?
 
Screeding gives the best performance (@70mm is best) as it acts as a thermal store and emits heat over time.
 
Bodgedbuild said:
Are you mixing up me and the OP? My wooden floor was about 70% of the area and the other 30% was concrete. I never did like my wooden floor but my hand was forced due to the damage to it caused by the builders. The 30% concrete part was new and already had Celotex under, the old suspended floor, fortunately, was above a substantial concrete base.
Click to expand...
Yes, apologies, I think I did.

@Naresh2022 , I guess your options will be determined by your floor levels and how much height you have to play with. With a screed you have to insulate below otherwise some of the heat will travel downwards and it then defeats the purpose. This is the traditional way to run UFH and works extremely well of course, insulation is key.
The overboard system works well where height is restricted but it works in a different way. In effect it heats the floor surface above it, rather than it heats a thermal mass and that then heats what's above it. It works in the same way spreader plates would on a wooden suspended floor. The overboard system is insulated therefore most of the heat heads upwards into the floor covering.

I have used the EPS 400 boards several time now where height is an issue and have found them to work well. They have been tiled on top of directly, engineered wood and carpet (with a cement backer board and underlay)
 
@Madrab : My current wooden floor is 50mm low the DPC level (this is 1940 built) not sure why it is low. So I have 50mm to play around and I can bring my concrete floor to the same level as I haven't done my slab due to various reasons.

I think I am okay to use Overlay floor panels 18mm boards on both wooden and concrete subfloors.

The only question is whether anyone used it and do I need screeding? Can I place tiles on top of it directly(without screeding)?


upload_2022-5-10_12-39-20.png
 
Use a thicker board with the 200micron foil, you can get a 20mm board for 15/16mm pipe @ 150mm centres. The thicker boards gives a bit more insulation and resilience. I wouldn't recommend it lays directly on concrete rather have a layer of high density insulation or wood below it. Though they say it can.

When I've used it, it sat on concrete, then a DPC, then 22mm P5 chipboard then the Overboard. The chipboard acts a bit like a thermal barrier and stops heat leaching downwards into the concrete. If going onto a wooden floor then I'd ensure it's very well screwed down and a flat as possible. If it's floorboards, I'd think about lifting them and using an 18mm backerboard or an OSB/Ply/Board

If tiling then a self leveling layer or a 6mm backerboard can be used, then lay tile/flooring directly onto that. Though the foil covered boards do say that the flooring can be laid directly on top. Shop around, you should be able to get them cheaper than your advert.


These overboards are not really designed for screed, you use a different approach for that.
 
Thanks Madrab.


For my concrete floor thinking for the below options (I only got 450mm space).

Option 1:
Hardcore 100mm + Sandblinding 50mm + DPM + Kingspan 100m+DPM+ Concrete 150mm + DPM + P5 Chipboard 22mm + Overlay board 18mm for UFH + Tiles 12mm.
100+50+100+150+22+18+12 = 452mm


Option 2:

Hardcore 100mm + Sandblinding 50mm + DPM + Concrete 150mm + DPM + Kingspan 100m+ DPM + P5 Chipboard 22mm + Overlay board 18mm for UFH + Tiles 12mm.
100+50+150+100+22+18+12 = 452mm


Is Option 2 okay? is anyone used like that? is P5 Chipboard able to stick on it?

Is anyone got better options please?
 
100mm MOT1, little bit of sand (dont need much if MOT1), DPM, 100mm concrete, as much insulation as you can, decoupling layer, UFH pipes then liquid screed 55mm ish?
 
But I’m trying to avoid screed and like to use 18mm overlay boards and tile it?
 
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