Electric UFH for first floor bathroom

[Meabh]

Hi - building a new house and have wet UFH on the ground floor only. We have electric towel rails in the bathroom and I also want electric UFH in the bathroom as we will have a microcement floor.  Our current floor is Caberdeck on posi joists which will be insulated underneath.

 

I'm using a special microcement shower tray which is 30mm deep and rock solid. We need to build the floor up to this (fine with the 30mm as we have carpet and underlay etc in the bedroom.)

The screed guy who did my sand/cement screed on the ground floor suggested 18mm ply, UFH, 12mm ish self levelling screed to get to 30mm.

 

So questions I'd love some help with please

 - what about some insulation? Do I need it? I want the heat from the GF to trave upwards.

 - what do you think of the ply/screed buildup?

 - how do you stop the screed leaking out of the room?

 - best brand of electric UFH for this?

 - the microcemnt company said an alternative was to do 18ply, UFH then 12mm cement board (glued and screwed!) - would that be easier/cheaper?

 

Many thanks

 

[nod]

Ply for tiling went out with the arc 

I use this on most of my jobs Insulated and different thicknesses