How to Insulate a Garage Door

Shop for materials

You can buy two types of garage door insulation kits at home centers. An R-8 vinyl-faced fiberglass batting kit provides a relatively high R-value. (Two examples are the ADO Products Single Garage Door Insulation Kit, No. 1611025, and Owens Corning Garage Door Insulation Kit, No. 500824.) It takes two kits to insulate a typical 16-ft.-wide garage door. Or you can buy precut R-4 expanded polystyrene (EPS) panel foam online (one choice is the insulated garage doors Kit from Cellofoam). Just cut each panel to length and bend and snap it into the horizontal rails on your door. However, at R-4 per inch, EPS has the lowest R-value. If you live in a moderate climate, that may be enough and could be cheap insulation for a garage.

If you’re willing to do a lot of precise cutting, you can achieve a higher R-value, up to R-9.8 with 1-1/2-in.- thick foil-faced fire-rated extruded polystyrene (XPS). (Johns Manville CI Max and Dow Thermax are two brands for a garage door installation kit.) Unfaced non–fire rated XPS rigid foam should not be used for insulated garage doors. It’s extremely flammable and when ablaze, yields toxic fumes.

Next, buy enough doorstop vinyl weather stripping to seal the top and sides of your garage door. You’ll also need new vinyl bottom seal to fit your existing track, or buy a new track if yours is damaged.