I have a bedroom / bath suite located above my garage. The garage is unheated, and this is Michigan. Needless to say, the floors of the bedroom are COLD! We have a section that is carpeted, and a section with hardwood floors. Fiberglass insulation is currently occupying the floor joists.
Can we pull up the carpet, drill some holes, and blow in cellulose to fill in any gaps on top of the fiberglass? Or maybe spray foam? Any other ideas?
Our current thought is to buy Atticat insulation from Home Depot and rent the blower to install it. We would rig a "funnel" type contraption to convert from the 3" blower hose to a smaller-diameter opening made in the floor by our drill.
There's no guarantee that your actually filling anything in the floor joists. Only one way to make sure, and that's what Ron said, pull down the ceiling in garage and re-insulate. Rooms above garage's are tough. Best to have some heat in garage, but I know that's not an option sometimes. Radiant, is probably what you want to do. Thought this was gonna be easy didn't ya.:-)