Simple answer is use the mapie renovation screed system straight onto the concrete slab set markers up on the slab and build up the height you need before laying the overlay system , as the guys above have commented you need insulation directly under the heating pipe , you have either misunderstood the advice given or a are determined to do it your way ? , but please be aware if you dont follow the correct installation procedure as stated by the manufacturers of the system and the the screed over the pipe cracks because of its thickness of cover over the pipe caused by heat expansion and movement which I think it will personally then it will wreck the tiling connected to it's been proved time and time again , we really are only trying to save you alot of aggro further down the line it's your choice now , mapie renovation slc with fibres in it is a brilliant product which I have used myself on many projects and can be built up to 40mm but really is not the the way you should be using it now again please reconsider the way you are going to proceed. Regards kop
