I just bought a condo which has two uninsulated 8′ garage doors. I like to work in my garage, and live in Virginia, so keeping it cool in the summer is more important to me than keeping it warm in the winter.
I had purchased Owens Corning garage door insulation kits (vinyl faced fiberglass bats) with an R value of 8. However, now I’m seeing radiant barrier kits and is has me second-guessing my decision.
The doors are white, and soak up the sun since they are south facing. I’m wondering if I could get the best of both worlds by applying a radiant barrier next to the metal door, then the fiberglass bats. To decouple the radiant barrier from the door itself and create an air gap, I’m thinking of using some thin foam insulation strips, or even just large dollops of construction adhesive.
The cost of an insulated garage door is well over $1000 (each) and has to meet all the HOA rules for looks, etc.; I can do this for well under $500 for both doors even using both types of insulation.
Do I try to combine the two systems, or just go with one? If I only go with one, which will do a better job of keeping me cool in the summer? I can’t seem to find any actual data, and am hoping the FHB community can point me in the right direction.
Replies
Looks like the kit you referenced is designed to fill the cavity of typical stamped steel garage doors.
the plastic spacer clips are nice but look sized to support the fiberglass with the plastic facing.
You might get away with a layer of reflectix next to the door, but I would skip additional spacers. Reflective insulation does work best with an air gap, but for an operating garage door, you do not have much room to work with.
I would use the tape and clips in the fiberglass kit, and if you want, put a single layer of reflectix ,cut around the clips, against the door.
Is your door a one-side stamped metal door?
Yes, it’s a stamped metal door. I need the air gap for the radiant barrier to work, otherwise the barrier will just become a conductor.
The reflectix page says it is good for R4.2 wrapped around metal duct work, seems similar to a hot garage door.
White reflects the sun, it doesn't soak it up. All you need is some R5 foam board cut to fit the bays. You might even be able to fit 2 in. You'll never know the sun is shining.