Revisions log for Answer #51

When using an underfloor heating system in an old building, the key is to fit as much insulation as possible into a small space. Deconstruct, then I would test the construction XPS boards to see if it fits the load of the kitchen. Then you don't need additional screed, you can tile directly or put a heating system in between. Alternatively or additionally, you should also insulate the basement ceiling (in all rooms), if the height of the ceiling in the basement allows.