The one I fitted was also in a wet room, so I will explain the problems in the hope you don't make the same mistakes.
1) The builder used out of date tile cement, whole lot had to be lifted and new heating element as he damaged the original.
2) The 90° bend on the sensor pocket was too sharp, and when the sensor failed it got stuck in the pocket.
3) We used sculptured tiles for grip, but they held pools of water so they took longer to dry.
4) The air into the room was from the hall, which was cool, so the extractor pumped out more heat than the floor could replace, lucky also had a towel rail so room was really heated by the towel rail.
5) On using the shower it cooled the floor, we really did not expect this, one would have thought hot water would heat the floor, once cool it took an hour to re-heat, and if the floor was scraped into drain, to get rid of water in sculptured tiles, it was still 2 hours from using shower before floor was dry.
6) The thermostat failed.
7) The sensor failed.
8) The shower had to be replaced, was a power shower, but when system boiler was replaced with a combi boiler law says can't use power shower, from then on could not wash ceiling with shower, not that we really wanted to, but shower power was much lower.
9) The under sink cupboard which was claimed to be for a wet room fell apart.
10) The sink fell off the wall as it seems it was only supported by the under sink cupboard, although it took a year after cupboard was removed before the silicon sealant gave way.
We found that the insulation put under the floor before fitting the under floor heating resulted in the floor being no where near as cold as rest of house it was on the ground floor, my mother was an amputee and the idea was to try the floor, in real terms it did not work, a simple mop did a better job, we had expected that is she waited 5 minutes in shower once complete the floor would be dry, no chance it took 2 hours, so to use the wall mounted toilet it needed mopping.
My sister would not allow use to do the wet room our selves, she said we never completed a job, to be fair likely true, so she found a bathroom specialist firm to do it. Main thing was time, it had to be ready when mother came out of hospital, it wasn't ready so she went into care home for two weeks, and still not ready when she came home, she had to basic live in a building site and after another two weeks my son lost his temper with them, and they walked off site, so thinking they had done it all correct, we informed the LABC we were taking over the work, seems builder had not submitted anything to LABC and they came to inspect, they said it all seemed OK, however they missed that one lintel on door way was only supported on one side where they had moved door opening.
They wanted us to employ some one to do the electrics, my son said OK as long as they are higher qualified than my dad, he has a degree, only then were we allowed to do electrics our selves. We had to rip out nearly all the builder had done because of the out of date tile cement and start again, that took about 3 weeks, the only bit we did not DIY was the lintel we had a builder do that for us.
The whole job was a nightmare, and my poor sister got the brunt of it as she has insisted we used a builder. And after all the problems with LABC on completion they did not even look at the job, the completion certificate just arrived in the post, after I had submitted the installation certificate for the electrics. It was done around 2004/5 and we left house in 2019 after my mothers death, we did use the under floor heating, but it was not really worth all the hassle, had we not need the special tile cement for the tiles on the heating cables then likely it would not have been out of date, and the builder would have finished on time, although with a lintel only supported on one side.
Because it was for mothers disability there was no LABC charge, but the inspector was rather short with us for not telling them before starting the work, we said we thought builder was doing it, but he said it was owners responsibility to tell them not builder. We tried to get money back off builder, but council beat us to it, and result builder was declared bankrupt.
I really do hope your wet room goes better than ours.
