How do I insulate a garage door?

A foam-panel kit is an afternoon job: measure the gap between the rails on each door section, cut a rigid panel to fit, and press it in. The panels add weight to a door that is held up by springs, so the last step is a balance test, and a door that fails it is a job for a pro.

What a kit is

Most kits are rigid expanded polystyrene (EPS) panels. One common kit has eight panels, each 20¼ inches wide, 54 inches long and 1¼ inches thick, and it insulates most standard 8-foot or 9-foot doors.^[1] Another maker's kit covers 60 square feet with eight pieces and lists an R-value of about 4.0 per inch.^[2] R-value is a measure of insulation's ability to resist heat traveling through it, and the higher the number, the better the thermal performance.^[5]

Reflective (radiant barrier) kits also exist. One maker's kit has eight panels, each 4 feet long, held on with adhesive squares that need 24 hours to become fully stuck.^[3]

The foam panels sit on the inside face of each section, between the horizontal rails, and the extra length goes behind the vertical rails.^[1] If a section has no inside channel, a kit like this is not the right choice.

Before you start

• Wear safety glasses. The kit's instructions list a straight edge, utility knife, tape measure and safety glasses as the tools required.^[1]
• Work with the door closed and the opener unplugged, so nobody can press the wall button.
• Keep hands and fingers clear of section joints, track and other door parts while working, as the door maker advises.^[7]
• Leave the springs, cables and bottom brackets alone. One door maker warns that attempting to remove a torsion spring assembly without proper training or tools may cause an uncontrolled release of spring forces and serious or fatal injury.^[7]
• Wipe the inside of each section so the panels and any adhesive sit flat.

Fit the panels

Measure the length between vertical rail A and the inside edge of vertical rail B, then cut each insulation panel to length.^[1] Break off the insulation where it is cut.^[1] Measure every section: they are not always identical.

Insert the excess insulation behind the vertical rails, then insert the panel between the horizontal rails with the channeled or grooved side facing the garage door.^[1] Work one section at a time from the bottom up.

Keep foam away from heat

Polystyrene foam is not a finish material. One maker warns that the product is combustible and, if exposed to a fire of sufficient heat and intensity, may burn rapidly, so it should not be left exposed or inadequately protected.^[2] Keep it off hot surfaces and away from heaters. The same maker says to protect expanded polystyrene from hydrocarbons, coal tar pitch, solvents and solvent fumes.^[2] Follow your local building code for how the product may be used.

Test the balance afterward

Insulation adds weight. A properly operating garage door is "balanced", meaning the door stays in place when stopped in any partially open position.^[6] A single car door may weigh as much as 200 pounds^[7] on its own, so even a few extra pounds matter to springs sized for the original door.

To check, close the door, pull the quick release to detach it from the opener, and lift it by hand about halfway, keeping hands clear of the section joints and your feet out from under the bottom edge. A severely unbalanced garage door could unexpectedly crash to the floor, possibly striking someone under the open door.^[6] If yours drifts or drops instead of staying put, do not use it; call a pro.

Stop and call a pro if

• The door will not stay where you leave it. If doors are not balanced, or if they bind or stick, they should be serviced by a professional.^[6] Read is it safe to replace a garage door spring yourself for why you should not adjust the springs.
• The opener strains, or the door reverses, after you add panels. The load has changed, so have the springs and opener checked.
• Sections are dented, cracked or sagging, or hinges and rollers are worn. Insulation will not fix that; see is it worth repairing an old garage door.
• The door has no room behind the rails, or is wood, glass or heavily windowed and a kit will not fit.
• The door is old and the real problem is its condition. A new insulated door may be the better spend: how much a new garage door costs in Virginia.

After the panels

Seal the edges too. Clopay advises making sure weatherstripping is in good condition to prevent heat from escaping.^[4] For the money side, see how much garage door insulation costs in Virginia and whether insulating a garage door is worth it. Browse more garage door answers or garage door pros on Loclis.

If you would rather not do it yourself, or the door will not balance, describe the job and local garage door companies quote it.