Garage Insulation & Air Flow

[Andrew Ulsher]

Anyone gone through the exercise of upgrading their garage to be more comfortable by either adding insulation in the walls/ceiling/door and adding vents/fans to the walls/ceilings/doors?

I'm trying to get ideas on how to make my oven of a garage cool enough to tolerate during the summer and late spring. I currently have a single fan that works if moved towards the back of the garage but that comes with kicking up sawdust, papers, and getting in the way. I typically put it up front as a pseudo exhaust fan but that does not help with the temperature as much.

Curious to what other creekers have done to increase the comfort in their garages.

[Gary Gill]

My garage has a pull down stair access to the attic. I block the pull down stair open 4-6" and let the heat rise while the overhead door is open about 12" off the floor.

[Andrew Ulsher]

I'm debating intake vents and exhaust fans on the garage door or punch a hole through the ceiling and install exhaust fans to blow into the attic or out the roof.

[Mike Snead]

I'm planning to insulate the attic area above, foam insulate + better seal the overhead door, and then use a small portable A/C unit to keep it more bearable than 95 with 90% humidity in Central FL. Eventually I may upgrade to a mini split unit way down the road.

Not much help, since its all only in my head, but I suspect it will keep me from sweating on projects during the warm season.

[Andrew Ulsher]

Any concerns with moisture build up with adding insulation to the garage and adding a portable A/C? Everything I seem to come across has some slight concern of moisture build up in the walls/ceiling when trying to make a garage more bearable by insulating.

[Mark Patoka]

My garage walls were already insulated so I added insulation to my attic. I noticed an immediate 5-10 degree difference, especially in the hot summer and cold winter temps. There was also a ceiling fan that blew into the attic and would kick on when it got to a certain temp but that burned out a couple years ago apparently. I need to look into it more and probably replace it and that may help with a little more venting/airflow in the summer.

[Bruce Page]

You don't show your location but here in the southwest I use an evaporative cooler that brings in fresh air from the outside and gets vented out through the attic/attic turbine. It works pretty well up to 90°-95° outside temperature. Above that, it's time for a cold beer.

[Andrew Ulsher]

What brand and size of evaporative cooler do you use Bruce?

Do you need to keep the door shut and have a vent to bring in the fresh air?

[Bruce Page]

Andrew, it's a Champion 2800CFM side draft. I wish I had gone with a little larger CFM.
I keep the doors closed, I vent it directly through the attic.

[Andrew Ulsher]

Any issues or concerns with moisture building up in the garage, or does the exhaust vent in the attic help with that? Any tips on venting to the attic?

[Art Mann]

My shop is free standing and has windows in it. I put the largest window fan that would fit in a window on one side of the shop. I just open the window on the opposite side of the shop and use the window fan in exhaust mode. That makes it comfortable up into the mid 80's. A fan installed in the ceiling would do the same thing for you if you have sufficient ventilation to pull in lots of fresh air and allow hot air to escape the attic. An exhaust fan has the side benefit of removing dusty air from inside the shop. I don't filter the air -- I replace it.

My shop is two story and there is 4 inches of insulation in the down stairs walls and 6 inches in the first floor ceiling joists. That also helps quite a bit but more so in the winter. Of course, when it is in the 90's outside, no amount of insulation will hold the overnight cool temperature for very long.

I have a room air conditioner in another window and it will cool the interior to 75 degrees on a 95 degree day but i don't like to use it. I prefer putting up with the heat and exhausting the dust laden air. I am mostly a hobbiest and I just don't work out there in the heat unless I have a paying job.

[Andrew Ulsher]

I'm starting to wonder how difficult it would be to add a window or two on the exterior wall and an exhaust vent/fan in the ceiling to the attic.

Long term would be insulation in the exterior wall, with short term adding insulating to the garage door and finding a way to help it seal around the sides.

Short term, a second fan to pull the air in on the wall and another to push it out creating a good airflow pattern would also be helpful. I need to do more research on evaporative units and the ductless units by Mitsubishi as well.

[Bruce Page]

Any issues or concerns with moisture building up in the garage, or does the exhaust vent in the attic help with that? Any tips on venting to the attic?

Andrew, I installed a static ceiling exhaust vent that has a flapper door. I also installed a standard roof turbine on the roof. When the cooler is on the air pressure opens the vent flapper, flows through the attic, and exhausts out through the roof turbine. Like I said, it works pretty well if the outside temps are below 90°-95°.
Evaporative coolers only work well in areas with low humidity. Our RH is typically in the teens or low 20's (22% as I type this). It may not be an option for you in San Antonio.


I keep all of the cast iron waxed with Johnsons paste wax and have not had any rust issues.

[Allan Speers]

Any concerns with moisture build up with adding insulation to the garage and adding a portable A/C? Everything I seem to come across has some slight concern of moisture build up in the walls/ceiling when trying to make a garage more bearable by insulating.

The only thing I can add to this is, get the SMALLEST AC unit that will still cool the room. This is because it will run more, and thus keep the room dryer.

They also, of course, make split AC units with built-in heat exchangers. I'm not sure how efficient they are, but it's definitely something to consider.

[John Stankus]

What brand and size of evaporative cooler do you use Bruce?

Do you need to keep the door shut and have a vent to bring in the fresh air?

We are too humid in San Antonio for an evaporative cooler. If you have a window, a window unit ac can make life more bearable. I put in a minisplit ac which works pretty well. An alternative that I used before the minisplit was a window unit that I mounted on wheels. That I clised the garage door on. I made a canvas skirt to hang down from the garage door.

John