Wet Underfloor heating in house with both concrete and timber floor

11 Jul 2007
Reaction score
United Kingdom
Imagining the kitchen as a battenberg cake,
Squares 1 and 2 (bottom) are concrete, which due to the age we don't think are insulated
Square 3 (top left) is suspended timber.
Square 4 will be a new extension.

What is the best solution for flooring and wet underfloor heating?
Best would be a combination of costs and efficiency.

We have looked a solution which we can lay on top of the existing concrete and timber floor.
We have looked at solutions with limited screed to minimise the step with the rest of the house

Would lack of insulation in existing concrete floor cost us dearly in the long run?
Would running over both concreted and suspended timber cause issues?

Sponsored Links
Not only will no insulation be expensive in fuel terms but you will find it difficult to heat the room as well as the floor because of the finite heat output of UFH tubing.

I would say that if you could achieve 50 mm of Kingspan then you will have a good chance!

Mixed floors are not well suited to UFH. So why do you want it so badly?

Thanks for the reply.
I wouldn't say "we want it so badly", rather we like the idea of underfloor heating, as have seen in other people's houses and as such are looking into it.

It sounds like we should take up the floors (2 concrete sections and 1 timber section) and concrete with kingspan the whole space

You don't have to take everything up. And could manage with just 50 mm on the concrete parts if you could accommodate the increase in floor height.

But do really need 100 mm of insulation under the UFH pipes.

If you can manage the long heat up times of UFH then it does give a very high degree of comfort.

Sponsored Links
Compact, there are times when a square peg does not fit the round hole, but with a little manipulation, even that will happen
There are 'experts' here who seem to know everything about everything without having hands on knowledge of a topic being discussed

Look at low build underfloor systems. I installed such a system at my son's place ON CONCRETE FLOOR There is no massive amounts of kingsman or underfloor insulation other than dedicated panels that take the pipe. You may not get performance of fully speced UF system but my boy, his wife and my 7 month grandson are happy as dog with two tails

If you want to have an install in a particular manner, talk with the manufacturers instead of on forums like this as advice given may put you off. Equally, you need to be able to read between the lines to make sense of what is being said and need to have some understanding of task in hand to get it right.

Good luck with your project

If you want serious advice, there are guys on this forum on whose advice you could secure an aircraft carrier. You will need a thick skin but advice given will be kosher
I like polypipes overlay system, 18mm cement board that then acts as a floating floor never had any problems with it, id ring polypipes tech department directly and they will point you in the right direction
If you must use an overlay system then at least ensure there is the proper 100 mm of insulation in the areas where that is possible.
For an UFH system to work efficiently you really need a good amount of insulation under the floor. Heat transfer goes in all directions and you want it into the screed and not down into the concrete slab/ground.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links