Originally Posted by Sir Ramic

Just been asked to lay UFH in a wet room but i am concerned due to the fact that the waterproof membrane supplied is to be stuck to the 18mm chipboard floor by peeling the back of the membrane.
I have just read something online from the makers of another UFH system similar to the one i am using (Devi Mat) that a 3 - 6mm gap must be laid between the membrane and the UFH.
It still sounds a bad idea to me but what do you think?
Going to have ameeting with the client on Friday to discuss other stuff so i need to be armed with info.
With the membrane (2mm) the spacing using levelling compound (3-6mm) the mat (3.3mm) the adhesive ( 5mm) and the tile ( approx 10mm) he will have one hell of a step up into the room...about 23 - 25mm.