Insulating the garage ceiling is important if you have an above garage living space, or simply have an attached garage. Installing insulation will prevent heat loss from the areas adjacent to the garage, as well as keep the temperature within an unheated garage more temperate.
In order to complete this project yourself, you should have exposed rafters. If your garage ceiling rafters are already enclosed, but not insulated, consider paying to have blown in insulation added to the cavities between rafters.
To complete this project, you will work with fiberglass insulation. First, be sure to choose insulation that is not too thick for the rafter cavity. Compressing the insulation in order to fit within the garage ceiling rafter cavity will diminish the effectiveness of the insulation. You should also purchase insulation that is the same width as the space between rafters. Finally, purchase fiberglass insulation with a paper vapor barrier backing, which will be easiest to install and allow you some flexibility when enclosing the insulation in the garage ceiling.
You must also wear the proper safety equipment while working with the fiberglass. A close fitting long sleeved shirt and long pants are a necessity. Plan on wearing gloves, safety goggles, and a dust mask as well to protect yourself from the fiberglass. A helper on the ground can also be incredibly useful when installing insulation in the garage ceiling. This person should help unroll the insulation from the ground, and help steady the ladder while you climb.
Step 1: With safety equipment on, climb up onto a ladder so you can reach between the garage ceiling rafters. Place the end of the roll of fiberglass insulation so it is flush with the wall edge and the paper backing is facing out, towards the room.
Step 2: Secure the fiberglass insulation to the garage ceiling rafter by stapling through the paper backing that extends past the edges of the insulation and into the garage rafter underneath. Space the staples 12 inches apart, and be sure to attach both edges of the insulation to the corresponding rafters.
TIP: An electric staple gun will save you significant time when attempting to complete this job. If you don’t have an electric staple gun, consider renting one to insulate your garage ceiling.
Step 3: Trim the insulation so it is flush with the opposite wall using a utility knife. Be sure to staple the corners to the garage ceiling rafters.
Step 4: Repeat the previous steps until all the cavities between the rafters have been filled with insulation.
TIP: Now is a good time to also insulate the garage walls, using the same insulation and techniques used to insulate the garage ceiling.
Step 5: If desired, cover the insulation with a layer of drywall.