Wetroom floor screed - does it have to be dry mix?

[Tim S]

I was wondering - if putting down 60-70mm of screed over 75mm celotex (actually Ballytherm) with UFH pipes tacked on:

does sand/cement screed need to go down "dry" (ie the usual bugger all water mix)?

Is there any reason I can't mix it wetter like concrete (minus the aggregate obviously) and tamp it down then rule it off.

To be honest, I don't get on with tamping dry screed down, especially in fiddly places where I want the screed to flow round difficult bits like drain pipes.

Just wondered...

Cheers

Tim

[Rob G]

I can't answer your question, Tim, but do remember to put a bias on the floor so that the water flows towards the drain point. A friend liked our wetroom facility, asked her builder to incorporate that into her new house and the stupid bugger laid it flat, so that every time you have a shower you have to sweep the water on the floor towards the drain.

Rob

[Tim S]

Rob G coughed up some electrons that declared:

Good point. I had realised that though!

I'm using an ACO stainless channel drain across the whole middle and sloping both sides (shower side and loo/door side) towards that.

75mm celotex insulation and UFH should see it dry quickly :)

Actually, I rang ACO today. Instructions say to set teh drain in a solid

8"x8" block of concrete, or something very similar. This seemed stupid. Fortunately tech bloke agreed it was bollocks. He said setting in screed layer would be fine, but set the drain first on a fairly wet bed of sand/cement onto the celotex, let it go off then set the rest of the floor in around it.

That's when I started wondering...

Cheers

Tim

[Theo Markettos]

Yup... around here (Cambridge), lots of the colleges are converting corners of rooms into 'en-suite' wetrooms so they can get more conference trade. There's quite a lot of variability even within one block of rooms as to whether they get the water flow right. They're a pig to keep clean, and it shows.

Best example I was in the other evening was slightly wider than a coffin - just about big enough for a toilet and basin. The shower head was sticking out of the wall above the mirror over the basin, with the control between the mirror and the basin. This was one of the better rooms (according to my host) - but there was still a fetid pool of water in the corner since the morning.

Theo