I have had a floor put on the ground and second floor of a house. There is under floor heating in some parts and none in others.
My concerns are:
1. The ground floor has insulation, foil etc but I am not sure the top layer is thick enough because it is not "solid" to stand on and in places (corners mainly) the floor is definately "moving" when you stand hard on it and dust raises from joins.
2. The second floor has similar problems and when standing in a door way where there are joins in the floor, rocking from side to side - foot to foot the floor is giving a little.
I am thinking that this is because of the insulation and may be normal.