Quite often, the garage is overlooked when it comes to older homes insulation needs. If you have a heated garage or have living space above your garage, you will want to ensure that it is insulated properly. Your garage ceiling is no different from an attic in terms of its importance in terms of retaining heat in your home.
For flat ceilings, you will want to achieve a minimum of an R-40 rating and for vaulted ceilings a rating of R-28. Flat ceiling typically have insulation blown into them while vaulted ceilings have batts installed in them.