So it’s currently 100 degrees F in my garage today. I’m sure it will only get worse as the summer goes on. I added some of those insulated garage door panels, but I don’t think they did anything.
Now I’m wondering if I should add fiberglass insulation to the attic space above the garage. Would this help, or just lock in the heat? Would using a radiant barrier up there work better?
You need some kind of vent fan to blow that air out of there. Like a thermostat attic fan for example, In the garage. I’ve seen people crack a window if you got it. Crack the garage door or back/side door when you’re home. Nothing is going to get rid of that heat except some ventilation of some kind.
Get/borrow a thermal camera, and use that to see where the heat is coming in. Some libraries have thermal cameras, but that might be rare. You can also get very cheap and nasty thermal cameras from Aliexpress for $60 AUD
You might’ve insulated your garage door, but did you weatherize it? You can get decent weather stripping to go along all 4 edges of the door to block off the cracks. As far as insulating your garage ceiling, it’s something I’ve considered too, but one thing I don’t have an answer too is how that would affect the airflow or code compliance for my gas furnace and gas water heater, which are both in the garage.
Also, when we did an exterior remodel, we discovered there was no insulation in the exterior garage wall, only in the walls shared with the interior of the house, so you may be contending with that. We had that wall insulated when we did the renovation, and it made a noticeable difference. I’ve also planted trees to shade that garage wall, otherwise it gets blasted with afternoon sun.
If I had the energy and time, I would put batt insulation above the garage ceiling and also replace my attic stairs, which are old and poorly sealed. A mini split AC would also be pretty sweet.
You might be interested in watching videos by Matt Risinger on YouTube, he does a ton on insulation projects in 70s-80s builds in Texas
I have the same problem with a different setup. Half finished walls. Nothing up except the roof. No insulation on walls or ceilings. 15 degrees hotter than outside.
Lack of insulation on roof and vents that are kind of blocked by the finished walls is my issue.
Solutions I’ve thought about are putting a vent up high, by the ^ of the roof. Putting a fan near that. Stapling insulation to the joists, just under roof, to keep some of that heat out.
Out of left field solution: get a heat pump water heater. It will be a lil loud tho.
Put in a radiant barrier. A radiant barrier is a layer of metallic foil that reflects up to 96% of radiant heat, assisting in the energy performance of a building.