Garage Door Insulation
 

Greetings all! I so miss my basement, but I am making due using the garage for my hobby. I build plastic scale models and I do a fair amount of painting so I need to plan to address the humidity and moderate the temperature in the garage. Already looking into a split AC unit but it was also recommended that the garage door be insulated. I plan to do this myself, but the question I have is has anyone else done this and does it make that much of difference. The AC salesmen I talked to said it could lower the temperature in the garage by as much as 20*. Living in MN, I know just having your car in the garage during the winter can have that much affect. Just trying to do some fact checking and look for product recommendations.

If you install an AC unit, you should definitely insulate the garage door and the ceiling above the garage. If you don't install an AC unit, insulating the garage door or the ceiling will not help much, if any, to cool it down. There is no way that your garage will be 20 degrees cooler with just garage door insulation. Insulation only slows down heat transfer, it doesn't prevent it, unless you are conditioning the space with an air conditioner. That is why the builder doesn't insulate unconditioned spaces in the first place.

It depends on the direction your garage door faces. A west or south/southwest exposure will generate a lot of heat in the summer. My garage door faces north, and an insulation tech talked me out of insulating the doors. He said the difference would be negligible. I did, however, have insulation added above my garage and lanai.

I saw some garage door insulation videos on YouTube. I have West facing door, so it DOES get hot. How much it will is somewhat debatable, but I might still do it, it is easy.

My garage door faces East, So I get the morning sun.

Another interesting point is the Attic space above the garage. We use it for a lot of seasonal storage. Mostly candles, just kidding...:) but would like to at least help that space out so wondering on pros and cons of not insulating above the garage.

The other part is that we are looking at cooling the garage and controlling the humidity. Cold air falls so does insulating the attic from the garage really make that much difference?

My metal garage door faces south, during the summer it's like a hot plate, you can feel the heat 3 feet off the door. Insulate the door with Styrofoam sheets and it will help lower the temp a few degrees.

Garage vent fan
 

I can't speak to the garage door insulation. A previous owner to my house installed a powered ceiling fan (about a foot square) in the garage ceiling that can be turned on/off. In addition, there were two vents placed at the bottom of the garage door so you can turn the fan on and it pulls air in though the door vents and vents it into the attic area. I've not used much as I don't work in the garage much but thought I would include this to give an idea.

I installed a wall mounted, oscillating fan in my garage. It's on a time, set to run for 2 hours every afternoon, from 4:00-6:00pm...

It definitely cools the garage...

"The AC salesman I spoke to said it could lower the temperature in the garage by as much as 20^." It is a matter of BTUs measure of HEAT. There is also humidity. Too big an AC will make the area like a cave-cold and damp.

Your application PAINTING adds another issue apparently not mentioned by the, "salesman." If, you will be spraying solvent based paints it is highly flammable-explosive. No one reads instructions. It says flammable, use in well ventilated area.

Personal story. I used to regularly walk past a guy, on my way home from work who purchased a gorgeous 1960's Jaguar. He showed me all by himself, he put up one of those opened gas heaters you used to see in stores. He apparently was spraying paint
in there. He blew up his garage. The flames destroyed his gorgeous car and he was found DEAD under the car by the fire dept.

Well aware of the need to use in a well ventilated area. I have gotten away from using solvent based paints and now using acrylics. It's been tough because I know how enamels and lacquers behave after using them for over 40 years, so the old dog is trying to learn new tricks. It's happening but not at a record pace by any stretch....

I picked up about 15 degrees. I did the door and the crawl space above the ceiling.

Ours faces north. We did insulate and marginal results..we're from Detroit Lakes!

We insulated our garage door and noticed a big difference! our gatage doesn’t get nearly as hot as it used to during the hot summer days.

I had a garage-to-attic ceiling fan professionally installed last summer. This cost around $800–much cheaper than an AC system. My garage door faces East, though I use a screen door all summer. However, I’ve only used the fan a few times. What was I thinking? If I park my car in the garage after driving it in the sunshine, it emits a lot of heat, and that’s when the fan could help most. But unless I’m working in the garage, why bother? Even when the sun is shining on the screen rather than the steel door, it heats up the garage a lot. But the fan is only going to pull in hot, humid air from outside. Also, the vents in the door installed by the man who installed the fan are near ground level, so the air pulled in has just flowed over a very hot concrete driveway and may be even hotter than the air eight feet off the ground. If the temperature outside is 90° and much hotter near the driveway, sucking it into my garage is not going to make it much more pleasant to work there. It’s still too hot. A better idea might be to leave my car outside for the day once I’ve had it out and it is hot. Using the screen door on the garage, the shady garage will usually feel cooler than being in the direct sun, even if it is still 90°. The previous owner of my house left a desk fan attached upside down to the ceiling aimed at the workbench, and that seems to help a lot more than than sucking air into the attic. The ceiling fan might work better in the evening, when the temperature drops, as it could gradually cool everything in the garage by twenty degrees. But the sun will heat up the garage the next morning, or parking a hat car in the garage will heat it up in a few minutes.

I installed reflective foam core garage door insulation and am VERY SATISFIED with the results. (Stuff I used is here: Double Garage Door Kit – US Energy Products)

My garage doors (3 car garage) are chocolate brown and face east. They catch all of the morning sun, and until I installed insulation radiated inward like pizza ovens. I took careful temperature measurements for several hot summer days before installing and several more hot summer days after installing the insulation.

Temperatures of the inside surfaces of the doors lowered dramatically, easily the 20 degrees mentioned in other posts, and on a few days up to 50 degrees different. HOWEVER, surface temperature of the doors isn't what you're living with when working in the garage. It's the air temperature that's important. So...

Before installing, the air temperature inside the garage would become 7 to 10 degrees above outside air temperature. Afterwards, inside air temperature remained 4 to 6 degrees below outside air temperature. In short, the insulation made noticeable reduction in the pizza oven radiant effect, not 20 degrees, but certainly cooler than the surrounding outside air temperature.

If you're also going to use a mini-split, the insulation will save it some work.