Garage Wall Insulation
Few people would dispute the importance of insulating exterior walls. But there's one exterior wall that often goes uninsulated -the wall that separates the garage from the house. Any house that includes an attached garage will have such a common wall.
An interior wall needs exterior treatment
The wall between an attached garage and the home's living space wouldn't normally be described as an "exterior" wall because it's actually inside the house. But in terms of thermal performance, this is definitely an exterior wall. The garage space is more like outdoor space because it's not "conditioned" (heated and cooled) by the home's HVAC system.
Insulating the wall that separates the garage from the living space is essential because the insulated wall "protects" the house from outside temperature extremes. But builders often neglect to insulate this wall, either out of ignorance or as a cost-saving measure.
A home energy audit performed by an experienced home energy analyst should establish whether or not the common garage/living space wall is properly insulated. If a garage insulation upgrade is needed, dense-pack cellulose insulation can be blown into wall cavities, or fiberglass batts can be installed in open stud bays.
Insulating all garage walls is a popular option
What about completely insulating the garage? Considering that many people use the garage for carpentry, woodworking or automotive projects, this is a popular option. If you have a garage workshop, it pays to insulate the garage so that you can work in comfort when it's uncomfortably hot or cold outside.