Electric UFH in wetroom-Do I lay onto preformed shower tray?

Hi folks, looking for some advice on my impending wetroom project. Pointed here by the tiling forum... next stop plumbing I guess!

The room will have a level floor and a preformed marmox shower tray.

My query is whether or not I should lay the Devi heating mat into this shower tray area? Is this ok?

If it isn't allowed, how far from the "true" wet zone should it go if it is not to be placed in the "wet" area. I'm aware of IP zones but not sure if this includes these electric UFH heating elements or where the zones lie in an wetroom "open" style showering setup


Looking for confirmation before I start work. It does have some bearing on how I will construct the flooring to get the right levels.

The idea of wanting UFH in a wetroom for me is more to accelerate evaporation of the standing water than to provide room heating or cosy bare feet (though its welcome for the comfort angle too!)

Thanks in advance.

Are you getting a registered electrician to do the work in the wet room? If so he will be signing it off and is the best one to advise.

There are a number of safety considerations - not just for the electric floor heating. And there are very specific regulations regarding underfloor electric heating.

Also this work is notifiable. See the DIY.NOT WIKI for details.

Have done the same with mother's wet room. We did not lay under tray and because more of slope it is not needed plus heated and cooled by water from shower.

We found although floor was nice and warm in fact any warmer mum would be burning her foot once shower was used the water from shower cooled them down too much for the drying to take place. This was worse since we used a sculptured tile to give more grip which tend to hold the water. Although slight fall outside the tray it was not enough to drain enough surface water for tiles to dry.

OK dry in 20 mins but my mother has finished and is out of room before it is dry.

A disappointment plus after 6 months the sensor failed and would not come out of pocket.

The mat was not cheap as the special type with earthed outer had to be used for wet room not the standard type.

There is no reason why it should not go under tray but it is not needed and level surrounding floor is no good it does need fall.

Although the LABC did not inspect my floor after fitting I think that was because we were both qualified electricians and normally they would want to inspect before and after laying tiles.

The LABC were also quite insistent on having the test results to show all complied with regulations and I got that feeling had we not both been qualified electricians they may not have permitted us to do the work.

My mother is unlikely to get any shocks from the floor anyway one needs two legs for that! Not quite true but because the work was emergency the LABC may have turned some blind eye in our case.