fitting underfloor heating

Its quite common over the last few years for people to want underfloor heating retro fitted to the home.
In this project we have a beam and block floor that has been infilled with polystyrene block as opposed to concrete blocks.
this poses a problem with height, as we will require 100mm of insulation, plus our 90mm of screed to cover the heating pipes. We are now removing the beams so that we can fit a new concrete subfloor from which to start building up our heated floor onto.
Nothing that phases us this time….not after this RSJ’s we are still having dreams about!