Exactly How to Insulate a Garage Door

If you have an attached garage with an uninsulated garage door, it’s costing you money in both winter and summer.

Studies done by garage door manufacturers prove that an energy-efficient R-18 insulated garage door can keep your garage about 12 degrees warmer in winter months and about 25 degrees cooler in summer. That reduces energy loss along the insulated walls and ceiling.

A new R-18 garage door costs about $1,400 (installed price for a two-car garage), so it really doesn’t pay to replace yours based on energy savings alone. You can, however, add insulation, doorstop weather stripping and a new bottom seal to your existing door to gain some savings and comfort. You can complete the entire job in about four hours for less than $200. Just buy the materials from any home center and gather up a utility knife, tape measure, straightedge, saw, dust mask, and a hammer and nails. Here’s how to do it.

Similar Projects

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 Garage Door Insulation 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.

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.) Unfaced non–fire rated XPS rigid foam should not be used to insulate a garage door. 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.

Insulate the door

We chose the R-8 fiberglass insulation kit from ADO Products for our door, so we won’t be showing you how to cut and install XPS foam panels in this story.

Start by washing each door panel with household cleaning spray and rags. Then rinse the areas with clean water and let dry. Next, install the retaining pins (Photo 1). Measure the height and width of each panel and add 1 in. to the length and width when you cut the batting to size for a snug fit (Photo 2). Panel sizes may differ along the door, so measure each one as you go rather than pre-cutting all the panels based on one measurement. Fit the cut insulation into the panel with the vinyl side facing into the garage. Then secure it to the retaining pins (Photo 3). Repeat until all the panels are insulated.

Mount the doorstop weather stripping

Starting at the top of the door, tack the doorstop weather stripping to the top jamb. Mount the side doorstops the same way (Photo 4). Then press against the door to simulate how much it might move in strong winds (Photo 5). Readjust the doorstop so it seals against the door even in windy conditions. Then pound the nails in all the way. If the door has too much play to adjust the doorstop properly, or you can see light through the doorstop weather stripping, replace your existing hinges with spring-loaded versions that press the door against the weather stripping at all times.

Install a new bottom seal

Most steel doors have a track along the bottom to hold a vinyl seal. The vinyl can harden from sun exposure and crack or break off in sections, letting in cold air. Installers usually crimp the slots at each end of the track to retain the seal. Open the crimps (Photo 6) and slide out the old seal. Then install the new one (Photo 7).

Test the door

A properly balanced garage door should stay in place if you lift it part-way and let go. However, insulation adds weight to the door, and that may throw off the balance. If your door falls after you let go of it, hire a garage door service company to readjust the spring tension. Leaving the door in an unbalanced state can damage your garage door opener.

Popular How-To Videos