The Best Way to Insulate a Detached Garage

Insulating a garage is a task you can perform yourself even if you possess little to no insulating experience. With a bit of planning, some basic tools, and moderate mechanical skills. you can insulate your own garage quite easily.

Choosing the correct type of insulation for your garage will depend on your budget, the climate you live in, and the size and construction of the garage itself. All insulation receives an R-value, which measures the material's ability to resist heat conduction. A higher R-value means that the material insulates better and is preferable for colder climates. Check with a local hardware store professional to determine what R-value will be the best benefit in your location.

The two most popular types of garage insulation are cellulose and fibreglass roll insulation. Fibreglass roll insulation is easily unrolled for installation on horizontal surfaces, but for vertical surfaces it must be installed behind the wall, which makes it preferable for garages that have not been fully constructed. Cellulose insulation is a recycled loose-fill insulation that can be blown into walls and attics, making it the ideal choice for garages that have been finished.

If your detached garage has yet to have its interior walls constructed, fibreglass roll insulation is the optimal choice. Simply unroll the insulation between the wall studs with the vapour barrier facing the inside of the garage. Use a staple gun to set a 1/2-inch staple every 2 feet along the insulation into the studs so that it stays snug. For attics and horizontal surfaces, simply unroll the insulation between the joists and allow it to lay flat -- it is not necessary to secure it with any fasteners. It is important not to compress fibreglass roll insulation because it will lose some of its insulating effectiveness.

If your garage is fully finished with interior walls, cellulose insulation is the best solution, as it will not require you to remove the walls. Use a staple gun with 3/4-inch staples to attach rafter vents into the wood framework adjacent to any soffit vents. The rafter vents will prevent any cellulose insulation from blocking airflow into the soffit vents. Prepare an insulation blowing machine according to the manufacturer's instructions and route the output hose into the crawl space above the garage. Start the machine and manipulate the hose from the crawl space so that the cellulose insulation is blown downward into the vacant wall spaces. Each space along the perimeter of the garage should be filled to the top with the cellulose insulation. After all walls are completely filled with insulation, continue blowing the material on the attic floor to insulate the ceiling.