Hi everyone, we are now slowly making our way out of the ground, Isoquick insulated raft is now down, what a speedy process that was - 1 day for 190m2 with the steelwork completed the following day. Just thinking ahead to UFH next week and the concrete pour. The UFH will be within the 250mm concrete slab. The slab will not be visible but will take the floor finish.

For the shower, I'm thinking of having it arranged as a wet room, which leads me to the first question. Has anyone had UFH under the wetroom shower part to help dry things out?

Secondly, I need to recess the shower area in this part - what have people used for formwork? I will need to recess the whole area of the 'shower tray' and then further from the waste below. I have an idea of how to construct but cannot think of how to keep this off the Isoquick and at the right height, etc. Any pointers?

Thank you

Jonny

Slightly different floor build than yours, but we used offcuts of insulation cut to the size I needed and a few very long nails to hold it all in place and the some concrete blocks on top to stop it floating off during the concrete pour. When I was ready broke out the insulation, did the drainage conections and back filled with concrete as needed.

1 hour ago, Jonny said:

Secondly, I need to recess the shower area in this part - what have people used for formwork?

Post a drawing of what you intend to get best feedback.

11 hours ago, Jonny said:

I will need to recess the whole area of the 'shower tray' and then further from the waste below.

I had the first Isoquick slab laid in England sixteen years ago and I had a similar problem in the wet room. I filled all the areas, where I didn't want the concrete, with blocks of the Peripor insulation. For the waste pipes this meant surrounding the pipes with Peripor which I removed after laying the concrete. That allowed the height of the waste pipes to be adjusted to suit the shower tray. The gaps around the pipes were then filled later.

Edited 1 hour ago1 hr by Gone West

On the UFH question, yes, I'd run the loops under the shower area as well. It's one of the best bits of a wet room, the floor dries off quickly after use and it never feels cold underfoot. A few things to plan for in your case though.

Watch the cover over the pipe where you drop the slab. Once you've recessed for the tray and then deeper again for the waste, you lose a lot of depth, so check you'll still have at least 50mm of concrete over the pipe in the recessed area. Keep the loops well clear of the waste and gully position so nobody breaks out onto them later, and take photos of the layout with a tape measure in shot before the pour.

You don't need a separate zone for it. In a 250mm slab it'll just sit at the same temperature as the rest of the room, which is what you want.

For the formers, Gone West's insulation blocks are the way I'd go too. I'd add a bit of foam adhesive under them as well as weight on top so nothing floats, and sleeve the waste in a short length of larger pipe so you've got some play to set the final height to the tray. Then tank the whole recess properly before the screed or tray goes in.