Insulating Rooms Over A Garage
Battle cold air from the top down
Two of the bedrooms in our 9-year-old house are located over the garage. In the winter, they are considerably cooler than the rest of the house. Can I insulate the garage ceiling to take the chill out?
Tom Silva replies: In a house as new as yours, the garage ceiling is probably insulated already. Adding more insulation might help a little, but I doubt it would be worth all the expense and effort. Remember, hot air rises, so most of the heat in those rooms is probably being lost through the walls and ceilings, not the floor.
That's why there are some other things you should do first: Make sure windows are properly weatherstripped to eliminate drafts, check that you have an adequate amount of insulation above the bedroom ceilings, and move furniture so it doesn't block any heat registers or returns. Installing carpet over a thick pad will make the floor feel more comfortable. And if none of these help, invite a heating contractor to see if the rooms are being supplied with enough heat in the first place.
Now, it's possible that the garage ceiling doesn't have enough insulation—you'll need to cut an inspection hole to find out. If you do need more, have a contractor blow in dense-pack
cellulose, which is so effective at stopping air movement it doesn't require a vapor barrier.