Removing 40mm from concrete slab to put in underfloor heating

Firstly, are you sure it’s the concrete slab, or is it in fact your finished screed later? Which may be sitting on top of W concrete slab. If that’s the case, simple remove all the screed and start again. To make underfloor heating effective you’ll need to insulate under the pipes/cables. You can get concrete ground down but very messy and expensive. Only other way is to cut back with a grinder to a step depth in lines everywhere and chisel out. Wouldn’t really recommend it. Try looking for a slimline system to retrofit.

Take a test area of your floor up, be careful to make sure there is no pipe work running through the floor, check there is foil backed insulation under the floor, 40mm is not enough screed. You need to take your concrete floor up, usually they are only around 100mm thick. If there is no insulation and you want to do the job properly, dig down at least 300mm lay and compact 100mm hardcore, blind with sand cover with new DPM. Lay 50mm of concrete (this helps prevent screed cracking) then 100mm foil backed insulation kingspan or similar. Lay underfloor heating.Cover in 65-75mm of screed. I know this sounds a lot of work, however if you want your heating to work most efficiently this is the way to go.

What would normally happen is the 100mm insulation would go down the underfloor heating pipe work would be attached to that then a floor screed made up of washed grit and cement would be layed on top of them and troweled off giving it a smooth finish , this can then be , tiled , carpeted , laminated what ever you wish .

Just check head height and remove skirting and lay underfloor heating and rescreed