Advice wtd wet ufh on suspended concrete slab

11 Jul 2007
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United Kingdom
We've bought a 50's house and renovating the kitchen.
The floor construction layout after knock throughs and extension will be (like a battenberg cake) 2 areas with suspended concrete slab and 2 areas of suspended timber, all equal sizes, to make up one large kitchen diner.

We would like wet underfloor heating, however we are concerned with heat loss to the concrete. We can insulate between the joists for the timber, but no access to below the concrete slab.
We would also like to minimise where possible the build up on the slab as this will create a step between front and back of the house.

Has anyone installed and or lived with wet ufh on a concrete slab?
Any suggestions on how much insulation (or how little), don't want to install a system that expends most of its energy on the slab.

We are thinking of engineered wood as a floor.

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You made me think about cake!
Anyway is the any insulation at all in the slab? If even 50mm polystyrene the bills would be bearable. The best flooring to go for would be as conductive as possible to get the floor surface temp as close to the slab as tiles.
I think it might be best to get out the breakers if no insulation, as you'll never get enough on top. You could then make all the floor the same. Whatever you do otherwise you'll have parts of the floor with quick warm up and parts with high thermal retention.
If your are doing the work under buildings regs, you will need to insulate to comply.

Dont fit underfloor heating over an uninsulated floor. If you are using the underfloor heating as a primary heat source you wont be happy with result; poor heat gain and high cost of running.

I would suggest using ceramic tiles that look like wood rather than engineered wood.

Im hot sure what you mean by suspended concrete slab?
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Thanks for the replies
Suspended Concrete slab, is how is sounds. The floor is hung from the walls / on brick stilts

There isn't any insulation in the slab, so we will be laying on top.

An alternative
In one of the areas, there is a build up of tiles, as they re-tiled 5 times over the years (it is more pronounced when you take out a wall and it's not just a step up at the door).
Because of this and the pain of removing them, we are considering smashing out the concrete floors and putting in joists, which then allows us to insulate between them.
Though smashing out will also be a pain..

We were looking at engineered wood, as it's more forgiving when the toddlers bounce off it headfirst...

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