Best approach for insulating garage to keep room above it warm

[dannycheeko]

We currently took possession of our 20 year old house last year, and noticed over the winter that the room over half the garage gets very cold, especially the floor.

Inside the garage, the portion under the room's floor is dry walled with blown in insulation in it. The other half of the garage's ceiling is exposed plywood, with nothing above it but shingles.

In the summer its very hot, and the winter is very cold in the garage, more extreme than it sometimes actually is outside... which probably means that the cold air is being trapped in the garage, cooling down the drywall, insulation, and eventually the room above it. (in the summer, the room above the garage is fine).

Should I remove the drywall and insulation and put in proper insulation?
or
Continue insulating the rest of the garage's roof?

or... and other ideas?

Thanks
Danny

 

[nealtw]

Do not insulate the roof of the garage, instead make sure the roof in the uninsulated part has plenty of vents both at the peak and the soffits. Add more insulation to the wall betweens mums room and the roof area and lastly you could pull down the ceiling under the room fill each bay with insulation for 2x10 floor use a 4" and a 6" bat to fill the whole cavidy after that cross strap the ceiling with 2x4s on flat and cut at least two holes to the outside so air can get in and around the area below the insulation.
Relace the ceiling with 5/8 drywall.
All area between living space and garage should have 5/8 drywall taped and filled for fire protection and to seal out offgasses from autos.

 

[Perry525]

When thinking about insulation, it is best to have the insulation as close to the comfort zone as possible.
With this in mind, I recommend installing a insulated floating floor.
If you lay at least 3 inches of polystyrene sheet closely butted over the floor and then lay a glued, tongued and grooved oriented strand board floor over, you will have a warm floating floor with no heat bridging and no direct contact with the existing cold floor.
At the same time you should consider fixing a double layer of drywall across the garage ceiling, a sheet of drywall offers a 30 minute fire wall, doubling this makes sense.