Cellulose is a loose-fill insulation that is growing in popularity. Made primarily from recycled newspapers and treated with a fire retardant, cellulose is usually blown into wall and ceiling cavities with a special blowing machine. Blowers can be rented at many tool rental stores, and home centers will sometimes loan you a free one if you buy your cellulose from them.

Because it’s loose-fill, cellulose is suitable only for finished garage walls and ceilings. If the garage is already finished (but uninsulated), you can install cellulose by cutting strategic holes in the wall material, spraying the insulating into the cavities between framing members, then patching the holes.

Rigid foam comes in 4 x 8-foot sheets and thicknesses of 1/2 inch to 4 inches. Rigid foam offers a high R-value per inch of thickness and can be cut to fit almost any space. It’s a good choice for thin walls and for insulating garage doors. If you’re turning the garage into living space or a full-time workspace and want to insulate the floor, one option is to use rigid foam covered in plywood or other subfloor material.

Spray foam is the most used insulation application for garages. It’s excellent for both R-value and for air-sealing. As a high-end material typically used for energy-efficient construction, spray foam is efficient in regulating temps, keeping moisture and pests out as well as keeping out excessive noises from the environment around you.