Wet-room floor construction and underfloor-heating

[mheden]

Hello,

I'm in the process of finalising the spec for a wet room. It involves the conversion of what used to be the original kitchen in a 1930s built house. The existing floor is constructed of 6-inch square very, very hard red tiles (quarry tiles??) set on a concrete base. The finished surface of the tiles is smooth and absolutely flat and level, but they're darn cold.

A builder I've spoken to has suggested lining the floor with a thin layer of ply fixed at 6-inch centres to provide a suitable base for the vinyl floor/shower covering. As well as providing a smooth surface on which to stick the vinyl, he says the ply will provide additional insulation against the otherwise cold surface of the tiled floor.

I haven't yet decided whether to specify the use of one of the "instant" wet-room solutions (the ones with the fall and trap all built into a unit ready to sink into the floor) or to go with some other approach.

What's the bset way to do this? Is a layer of ply going to turn an otherwise cold surface into something that's acceptable in a wet-room (given that it will have a layer of vinyl on top of it)? Should I be asking the builder to put insulation under the ply, or should I insist on ripping-up the floor and installing under-floor heating? Is it generaslly better to use one of the packaged wet-room solutions (to ensure consistency and accuracy of fall) or are there good reasons for sticking to a more traditional approach?

Any advice would be very welcome!

Thanks,

Mike

[Mike]

It's quite easy to remove those tiles with an SDS drill so I'd do that to gain some height for insulation and u/f heating.

[John Stumbles]

It's not that hard to break up a concrete base (with a big sledgehammer) and relay the floor with a proper insulation layer and wet ufh.

[Mike]

That might depend on how thick the concrete is. Also one has to consider the damp proof course (if there is one) might get damaged. I'd suggest doing a test drilling first.

But yes, if you don't mind the extra work then a proper insulation layer will be better. Not sure it is worth the expense of the wet u/f controller just for one small room though. Electric kits are sub £100.

[Christian McArdle]

Rip out the old floor. I'm not the greatest fan of wet rooms. However, if they are to work at all, they MUST have (a) insulation and (b) underfloor heating. Otherwise, you are just going to have a room full of depressing wet muddy puddles.

Christian.

[The Natural Philosopher]

Do not use underfloor heating without insulation. You wuill be pouring money down the drain

I have a couple of UF heated wet rooms. Nothing special. Just make sure the floor is soild and the drains are well sorted, because chances are thats teh last time yyou will be able to access them without ripping it up, and run the UFH pipes away from where toilte screws may puncture them, or you may need to rip up one day to clear a blockage. In your case bite the bulet, and rip teh whole flor up, and relay.

You need at least 2" of polystyrene, and enough screed depth to form a drain slope to your wastes. And a firtm subbase of probably 3-4" of conbcrete over hardcore with a DPM on top.

Pay attention to teh walls and skirtings amd make sure your tiles or other waterproof floor go up the walls well beyond splash height.

[The Natural Philosopher]

You can get away with insulation alone if the room is well heated. And the floor slopes properly.