Adding underfloor heating when renovating a bathroom

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We're about to start a bathroom renovation as we're ripping everything out and starting again I'm thinking about adding a wet underfloor heating system. Has anyone done this retrospectively and was it expensive/a complete pain? The house is modern-ish, less the 25 years old and the bathroom is on the first floor. Will adding underfloor heating change the floor levels to this one room? Eventually we'd like all of the downstairs rooms have underfloor heating, but at the moment the house is heated by radiators running off of a fairly old boiler. Can underfloor heating be added to my current system or is it more complicated than that? TIA!

We put electric underfloor heating in the bathroom, together with a radiator. On the ground that it wouldn't be on that much so would be relatively cheap. It's lovely to have the bath mat all nice and dry and warm. And the room is toasty as they put more insulation in.

We've just had wet underfloor heating put in a new extension - there was a lot of concrete involved, a new manifold that takes up quite a bit of space that controls that heating separately. It was a big job.

I agree with PP that electric underfloor heating is much more practical. The wires are in an almost flat mat, so have much less effect on raising the floor level. They are cheap and easy to install, compared with having to run water pipes under the floor.

Agreed. In our bathrooms we put electric heat mats under the tiles - a lot less hassle. We do have wet underfloor heating downstairs but it is very involved with pipes, new concrete screed over etc - only did it as part of major building work

Thank you all! I'd read that electric underfloor heating is very expensive to run, which is why I was looking at wet systems initially. Have you found its made much difference to your electricity bills?

Not much difference at all. I think if you were trying to heat a big space with it yes it absolutely would. But we have it on a timer in the bathroom and it comes on about 6.30 for an hour and we have it on in the evenings for about an hour. As I said we've got a radiator in there too and that provides the main heating. And we also insulated the room thoroughly before the tiling went up.

It's a lovely cosy room now whereas before it was rather cold...

Another vote for electric underfloor heating. We just had it installed as part of our new bathroom and it's so nice and cosy and means everything dries quicker.

wet UFH is not as much of a pain to fit retrospectively and should be more efficient than electric

Take up floor boards , insulate underneath as much as you can between floor boards
Fit spreader plates to house pipes and run pipe in them , this will need to go back to a new manifold
Fit new floor boards

Key to its success will be what you are able to insulate under neath the pipes with as the floor boards and floor covering act as an insulator

In a bathroom it has a solid floor/tiles so will heat that

Put a dual fuel or electric towel rail in the bathrooom so when your heating is off during the summer you can still dry towels

There is also an overlay system that can go on top of floorboards but it will raise the height by 18mm

You can get retrofit systems for wet which are designed to be lower profile, you will still get a small step but not as much.
I've put this in a clients house and it worked fine. We connected up to the existing boiler system they just connect a specific manifold for the UFH rather like adding another radiator. Whether or not your system can take it is worth discussing with a plumber but it's not usually a problem

www.nu-heat.co.uk/underfloor-heating/renovations/

The problem with retrofit is that UFH works best with much higher levels of insulation than is usually present in most homes so it's not as efficient as if it was designed in the building from the start.

Thank you all so much for this, its so useful. @billysboy I've never come across dual fuel radiators before- do you need two separate thermostats to run them, or can you control the gas/electric all from the same panel?
@wonkylegs yes I'm a bit worried about the insulation too- the house isn't too old but doesn't feel very well insulated at all. I'm assuming we'll need to put masses of insulation under the floor if it going to have even a fighting chance of keeping the heat in the room.

You don't need masses but at least some and the more the better it performs which is usually the main issue.
If it's upstairs then you can usually put some between the joists without too much issue. The problem is when you need to put it above a concrete floor then you end up with a step.

We've had no issues with UFH on a wet room floor. I also recommend porcelain tiles, (less expansion so narrower grouting) just ensure the floor is solid underneath.

Consider using a smart controller, that way you're more likely to turn it off when not needed, and tune the heat / time better.

Same question here! Following with interest.

Have a look at Sophie Robinson’s Instagram page. She added retro fit wet ufh to her house, there’s lots of videos you can see the process.

I had underfloor heating put in when we had our new bathroom installed. There is also a radiator in there and I have never used the underfloor heating once but it is there for when we sell and hopefully will be one of those enhancing little extra things buyers love :)

I am currently thinking of fitting electric UFH in my loft conversion, there will be 2 bedrooms and 1 bathroom. Are there any thermostats that anyone can recommend? I am wondering if I can install a multizone one to control all 3 rooms?