How to Insulate a Garage Door

To insulate a garage door is one of the steps I mentioned in my booklet about Home Cardio Theater. After a really pleasant Summer in Utah I decided it was time to insulate my garage door before the Winter chill set in.


First of all I measured my door panels and found there are ten panels in two rows of five. The left column is 50″ wide, and the right is 53″ wide. The top and bottom rows are 22″ tall, and all the others are 18″ tall. I decided to use Reflectix Bubble Pack Insulation to insulate the garage door for simplicity, as you can simply glue it in place using a caulking tube application adhesive. I chose PL375 Multi Purpose Adhesive since it’s rated for interior/exterior use, and this totally qualifies for that, as it’s exposed to both. I also like the easy soap and water hand cleaning.

How to Insulate a Garage Door

Glue to insulate the garage door panels
Glue on the garage door panels
cutting the Reflectix sheet with a utility knife
Cut the Reflectix sheet to insulate the garage door with a utility knife on a waferboard scrap and a furring strip guide

I cut the Reflectix with an inch overlapping all around and notched the corners, then put lines of glue on the garage door panels and around the aluminum flanges all around the panels. I carefully started at the upper right corner, lining up the bottom flange, and put the bottom edge of the silvery bubble sheet lined up along the bottom flange of the door, pressing into the glue lines. I then poked the middle of the top of the sheet under and into the folded top flange of the door panel, and going outward from there, lined up the top as I pressed it into place.

Reflectix sheet to insulate a garage door panel
Reflectix sheet insulation on the top garage door panel

I then lined up the right side of the bubble sheet against the exposed foam core of the door panel, and then swept the surface with moderate palm pressure to make sure it was in contact with the adhesive beads, and finally poked the left edge of the sheet under the left flange of the door panel. Now I have one insulated garage door panel. I then did the lower right corner, upper left and lower left, and began to fill in the center panels.

Reflectix used to insulate a garage door
Reflectix sheet glued in place on the bottom garage door panel
bottom edge of sheet lined up top center tucked into flange
Line up the bottom of the Reflectix sheet and tuck the center top under the flange to insulate the garage door panel

The left side was considerably easier to manage. The panels were smaller, and the center flange was not inset at all. One by one I put the panels into place, being sure to set the sheet into the adhesive beads with firm hand pressure. I worked while the sun wasn’t directly hitting the outside of the door, and the outside temperature was around 60 degrees F.

starting to insulate the inside garage door panels
Outside panels done, inside panels started

Finally I had the garage door insulation in place and in about an hour the adhesive will be dry and ready for exposure to heat and cold. It will be several hours before the sun is fully on the exterior surface. This insulated garage door will be the first step in converting the shop area (single compact car) of the garage into my Home Cardio Theater for use in the Winter.

Insulate a Garage Door - finished product
The finished insulated garage door

UPDATE March 27 2014:

After 1-1/2 years and two Utah winters and one Utah summer I am impressed with the performance of this relatively inexpensive and simple solution. The door faces West and gets direct sun in the summer afternoons and used to burn my hand when I touched it in the late afternoon. Now it’s quite pleasant. In the winter a small space heater running overnight will keep the garage above 50F. Previous to the insulation job it would drop into the low 30’s. That’s quite an improvement.

This is from my Garage Home Cardio Theater Project

Be sure to check out Planning Your Home Cardio Theater, sadly no longer available on Amazon for $.99 in which I mention some of these issues with the garage.


Submit this form and I’ll let you have a free copy.

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1 Comment

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