Insulating a garage door is worthwhile for many reasons. The main reason someone might want to insulate the garage is simply because they spend time in there. Be it woodworking, automotive tinkering or lifting weights on a home gym - these are all reasons why you would want the garage to be more comfortable when you're inside it. Opening a window or running a fan can help move air, but it won't stop heat from coming in so it does little toward creating a comfortable space. We are going to show you the method that is hands-down the easiest way insulate the garage door (the main culprit in heat gain) so you can be closer to a more comfortable space for whatever you're doing in there.
Bonus: creating a more comfortable space for a garage that is attached to the house can usually mean the room on the other side of the garage is a bit more comfortable too!
Step 1: Step 1: Gather Your Materials
For this installation you will need the following items:
- 4 sheets* of foil-faced foam board (pictured here is Perma"R" brand but there are several other brands available such as Johns Mansville, TUFF-R or you can make your own foil-faced foam board at home.)
- A knife/blade to cut the foam board
- A measuring tape or metal yardstick
*4 sheets of 8' x 4' foil-faced foam board will generally be enough to do a standard 2 car garage door.
Step 2: Step 2: Measure and Cut
After you have gathered all your materials, measure the size of each panel frame in the door (the metal that frames the panel). Then, add about an inch to the shorter dimensions and cut the foil-faced foam board into the rectangles. The reason you add an inch to the height of the rectangle is because you want the panels to be slightly larger than the actual framing on the door so that they are convex and curve outward when you put them in. This step is absolutely critical because if you don't create the air gap, then the foil will NOT work as a radiant barrier and you'll just be wasting your time. You can read why the radiant barrier foil requires an air gap to work, so if you just put the foam in flush against the door this method is not nearly as effective as if you create the air gap. Remember, this method is to primary reduce summer heat gain. There will be some benefit in reducing heat loss, but the big impact it to reduce heat from the sun beating down on the door.
When it's time to place the foam board into the frames, situate the foam so the foil side is facing the garage door and the small air space you created from the convex shape. Start by inserting the top edge in first, then "pop" in the bottom edge. The panels should be convex and have a curve outward that is visible when you look at them from the side (see the image above).
Step 3: Step 3: Finish It Up
Continue repeating step 2 for the rest of the panels.
Tip: save yourself the headache of wasted materials and measure each panel individually, you can't always assume they will all be the exact same size!
When you're done, you'll have the benefit of a radiant barrier as your first line of defense right after the metal door, and then you'll have the foam board to help slow down the little heat that makes it past the foil. The result? A brighter, more comfortable garage door that is properly insulated to help you keep radiant heat out in the summer.