Hello I recently finished rehabbing a 50 year old single story ranch built into the side of a hill, the basement is walkout and driveway goes around side of the house to garage which is part of the lower level.  Above the garage ( which is 25X 25 ) is a room which contains our kitchen and dining / living area.  I have a pretty warm garage i.e it is  “sort of heated” by several ducts off supply line and good new door with 2″ think insulation on it and stays about 50 some degrees when the outside temp is below freezing.  I replaced the subfloor with 1″ T&G and then 1/4″ fiber cement then the tile.  Despite the relative “warmth” the floor is still really cold, has a surface temperature ( as measured by probe) of within 5 degrees of the garage.  My logical solution is to insulate below and between the joists and then drywall the garage ceiling.  I know that would help, but maybe there is a better solution.     Above and beyond that I am wondering if it would be feasible,, and in there is any kind of radiant flooring product, that I could install between joists under the floor.  If so please let me know and if I did that would it be okay – or unsafe – or even necessary to insulate before drywalling garage ceiling.  I am also thinking something like this might cut my heating bills, as the other part of the house is warmer anyhow due to stronger airflow from central heating unit ( I have natural gas heat)., plus the thermostat is in this colder part of the house.  Any suggestions would be greatly appreciated.  My kids hate playing in that part of the house because the floor is so cold, once they get off the rug anyway.   Also the garage was drywalled when I bought the nails, but it was hung with nails and minimal glue and there were sags all over the place, so I brought it down when I had a 20 yard roll off at my disposal.   Thanks! -Freezing and snowed in, in Indiana