Garage Door Insulation Adds Comfort While Saving Money

The addition of garage door insulation should be one of the first considerations when renovating a garage. In almost every home with an attached garage its heating and cooling needs may be overlooked. Beyond the regular insulation needed for a garage’s walls you need to also consider garage door insulation to finish off the energy efficiency of the space.

A home’s garage, of course, does not need to be kept cool or warm, but you and your family do. In many homes featuring a second story, a living space is most often located above a garage (whether finished or unfinished). This leaves a bedroom or upstairs home office too cold in the winter or too hot in the summer. Completely insulating the lower garage space, starting with garage door insulation, is a good way to help curb energy costs.

Understanding R-Value

The first thing to know before buying any insulation is its “R-value”.  This is an industry measure of thermal resistance used to grade, or rate, a particular insulation’s ability to reflect heat and to resist thermal changes. The numbers are usually given in a very simple format: “R-8”; “R-14”, etc. The higher the “R” number, the greater its insulating abilities are. However, increases in “R-value” also mean material cost increases as well, so the savvy shopper should only buy what will meet his or her insulation needs and not go overboard buying the more costly, higher-rated material. In milder climates R-5 or R-6 insulation may work just fine, for example.

Types of Garage Door Insulation

Some garage doors by design do not need insulation. For example, hollow-core doors with insulating interiors need no additional help. Similarly, fiberglass garage doors are, by their very material make-up, self-insulating.

Owens Corning rigid board insulation

Typical Rigid Board - Owens Corning

When thinking about installing garage door insulation, there are several popular types of products available. Rigid foam board insulation panels are one such option. These are sheets of material like Styrofoam or compressed particulates that deliver roughly R-5 protection.

Fiberglass insulation like what most people use in their attic spaces (slightly thinner for obvious reasons) is also on the market. They have the advantage of higher R-value (usually around R-9); fiberglass insulation is also excellent for stopping air leaks.

reflective foil insulation for garage door

Reflective foil insulation is thin, but has high R value

Another fine choice is reflective foil kits. This type is a sandwich of two layers of heavy foil covering an air-filled bubble-wrap layer. The foil’s R-value is fairly high (around R-10). It has the added advantage of reflecting radiant heat and also acts as a moisture barrier.

Polystyrene foam is another widely used insulation material. Polystyrene door insulation kits are found in a variety of thicknesses and R-values. The kits have panels that fit snugly (horizontally) between the garage door frame rails. Most polystyrene door panels have a protective vinyl coat that makes for easy cleaning with but a swipe of a damp cloth.

Finally, for the more adventurous there is spray foam insulation.  Although this provides excellent coverage (filling gaps more efficiently) its installation is more involved than that of panels or foil. Once the foam has set up after install, however, it is a fantastic sealant.


In general, installation of garage door insulation panels requires nothing more than a tape measure, a sharp cutting utensil (such as a box cutter, scissors, or a utility knife), and a steady hand.

Fiberglass insulation once cut to the correct size, simply slips in each panel of the door. Hooks that come with the kits secure the insulation panels to the garage door. And, because each fiberglass insulation panel has a vinyl covering on it the garage door’s interior has a streamlined, finished look to it. Another advantage of the covering is not having to directly handle the fiberglass itself (for anyone who’s done that, it is itchy!)

Foil insulation being installed

Foil insulation being installed

To install reflective foil the first action is to measure and cut it to size for each garage door panel. This type is affixed with tape.  If a non-metallic “foil” finish for the interior is not to your taste, these kits are available in a white vinyl coated interior color as well.

Thicker polystyrene foam usually snugs into the door’s panel enough so no other tape or fasteners are needed. Thinner foam insulation pieces, however, will require tape to hold them in place.

Spray foam is the most more difficult to install.  A solid panel (of some substrate material, plywood, etc.) has to be cut and fitted between the channels of each section of the garage door, leaving a gap between the backing and the door.  Then, a special tool injects the spray foam between this panel and the exterior door forming an insulating barrier. Once it’s cured, though, it provides high R-value protection (10+)


As in all things, the cost of a garage door insulation kit is determined by many factors.  Buying a higher R-value product increases cost as does buying a higher-end brand name of material, such as Owens-Corning, Matador, or Atlas.

At the lower spectrum is the pink or blue fiberboard.  These run about $12 per sheet (4’ x 8’; 32 sq. ft.)  Thus the average garage door could be done with this method for about $36.00 worth of material (with an R-5 value). The polystyrene door panels, to cover an average double garage door, are about $160.00 in contrast.  Finally, foil falls almost in the middle, with an average double door cost of about $85.00 for the material.

But cost of material has a benefit. The US Government gives tax credits (ranging from $500 to upward of $1500 or more) to homeowners for increasing their home’s energy efficiency and that includes insulated garage doors. The other, more obvious benefit is in reduced heating and cooling costs, especially if the garage is conjoined to a living space. So, “cost” may not be a big factor for consideration.

Installing garage door insulation makes for greater home comfort and can be a very important part of a custom garage makeover. Beyond that, though, the “cost” might not only be free (having paid for itself in lower utility bills) but (depending upon which Federal tax credit you qualify for) by insulating a garage door you may come out ahead!

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