It's time to insulate my metal garage door. Our garage is underneath the living room and I'm sick of having cold floors. I've got a little over 1 3/8" of depth to work with. I'm thinking about using a layer of the aluminized bubble wrap stuff for radiant barrier (it's south facing and gets really warm in the summer) backed by a piece of 1" thick poly foam insulation board. I'm hoping to be able to friction fit all of it, but am not against glue if I have to. Thoughts on that plan, or any other ideas?

Go get some rigid foam insulation with the aluminum backing. It comes in 1" & 2" thickness and has the R-value between 5-6.5, depending on which manufacturer you go with. You won't be able to get much more R-value than that because of thickness. You can pick them up at Home Depot for around $20 for a 4x8 sheet of it. The other thing I'd suggest, if your garage ceiling isn't finished, I'd also get some batt insulation and put into the ceiling/floor joists. If it is finished, the only thing you can do would be to put a radiant heater in there without tearing into the ceiling.

I did the same as sbolt on my parents garage door. Was able to fit it tight enough to stay put without any glues and, it works great.

I'm not sure that 1" board will friction fit, but it might. I may try that first. I was thinking of using that board faced with this stuff:

http://www.homedepot.com/p/Reflectix-24 ... pOZEsRekmk

The total thickness should be just about right to cram into the pockets on my door. As an aside, the stuff I linked above is the same stuff that people are using for sound deadening on their floors, right? I'm contemplating a rubber floor mat with some deadening under it. I'm tired of my ears hurting after a long days in the truck. Then again, it'd probably help if I didn't turn up the Metallica to be able to hear over the tire roar.

I don't think you will be able to friction fit that stuff well enough to stay put without glue. being its already flexible to put on a roll. the insulation board, I was able to slip it into the "pockets" of the door sections and it hasn't budged in the past 12 years. http://www.homedepot.com/b/Building-Mat ... 5yc1vZbaxx any of these therma sheet panels can work well and you can step cut the edges to fit in the pockets. It will also bow enough to aid in making it fit tight as well. Paintable too! (not that the roll stuff isn't) whatever you decide will definitely be a big improvement.

I was thinking a layer of the roll stuff, which is supposed to have great thermal properties, with a layer of foam board behind it to support it and add additional insulation.

The problem you have with that rolled bubble wrap is that it doesn't have a high enough R-value (3.7). You are picking up cold floors because there isn't any R-value on the doors right now. We like to put doors on that are at least an 8 R-value on any garage that is attached to the house. Especially if it is under a "livable" portion of the dwelling. You can use a combo of the bubble & this stuff (6.5 R-value and it is only 1" thick) and it will get you up to a 10.2 R-value. You will notice a huge difference too. So, your initial thought is on track, but use insulation board instead of just a regular foam board.

http://www.homedepot.com/p/Super-TUFF-R ... pPCG-Iueh4

Thanks! That board looks like the way to go for sure. I went to home depot today and it looks like the 1.5” foam board might work since its squishier, but its only rated to R4.5 or something like that.

Any way you look at it, there is a ton of heat transfer through an uninsulated door and anything you do to stop that will help, both summer and winter. The other thing to look at is to make sure that your seals around the overhead door is still in good shape.

I'll double check them. They're only a year old, so i should be good there.

When we moved to TX and while I was helping move my sister-in-law to Alaska, my wife found a kit to insulate our garage door. Came with a plastic sheet backed foam board of some sort and some thin metal rods to use as stays. Worked pretty well, but I don't have any info on it.