Garage Ventilation ?

[ScottMac]

With the 110 degree days we've been having, my garage is getting way too hot inside. The tools are almost too hot to pick up! I've taken to running the door up in the afternoons and closing up in the evening after the temps drop. Ive got your typical 25 foot square freestanding 2 car wood framed garage with no insulation. Will a couple of roof vents be enough to lower the temp? Doesn't have to be cool inside but it's way too hot now.

 

[rusty_tlc]

Calculate the number of cubic feet and decide how often you want an air change, probably once every 2 - 5 minutes. Divide the number of cubic feet by the number of air changes. That will be the CFM you need to move, buy a gable mount electric fan that will move that many CFM. You can control it with a switch, timer or thermo stat.

 

[Music Man]

Or get one that is powered by solar.

 

[Living in the Past]

I have a 1,100 square foot garage that I use the security at night to cool the garage. It's finished and insulated. I plan on using a small fan in the attic excess panel. Then close down during the day. This is in a milder climate where it drops in to fifties at night and maybe high eighties during the day. My detached garage in the Phoenix area I have a old side draft cooler I put in a side door that works great as long as the humidity is down. When the humidity is up if I can stay in the direct path of the air it's not too bad. Air movement is the key. Once I insulate that garage I plan on installing a air conditioning. If your doing any type of welding, grinding or painting you want to make sure you have plenty of air exchanges even if you insulate A/C is not a good idea.

 

[Solace in Solitude]

Without seeing what you haven, it's difficult to give a proper answer.

We lived in Smithville,TX until 2012 - it's about 30-40 miles east of Austin and similar in heat and humidity (Colorado River runs thru town) to much of East Texas. The detached two car garage, in the back became my workshop. I rehabbed it and left the ceiling open for attic storage of all my woodworking materials and did not insulate it. I added a standard single garage door, in double width, with a 7' header.

To keep it cool, I used THIS VENT in the back gable (furthest from the garage door).

Then, I mounted THIS FAN behind the vent, wired to 110. It has an adjustable thermostat, I set it at 130* (remember, it's mounted just below the peak of the roof) and found that 130* was sufficiently low to draw outside air in and exhaust hot air out and keep,the heat down.

I also had a standard gable vent in the front, this allowed the fan to pull air in thru the front and exhaust it thru the back, when the garage door was closed.

That setup and one of those big orange Home Depot fans blowing the sweat off me, kept it comfortable enough to allow me to use that shop all summer. But, it ain't air conditioning...

Prior to Smithville, we lived in a custom home in Georgetown, TX. When we built that house I included air conditioning in my shop. I found a 5600 BTU 110V air conditioner kept my shop plenty cool. But, it was the size of a one car garage and was fully insulated.

I don't know if your garage is detached... Or, if it has a ceiling... But, maybe this will give you ideas...

One more story... one of my co-workers, at Randolph AFB (east of San Antonio), lived in a custom home, in New Braunfels, TX. He didn't add air conditioning when he had his house built.

Instead, he put gable vents at both ends of the house and installed a WHOLE HOUSE FAN in the hallway ceiling. They would leave the windows open at night and the curtains stood parallel to the floor, when that fan ran.

I stayed with them for two weeks, in the way to Holland and, once you got used to the noise of the fan, it was suprisingly VERY comfortable sleeping!!

Of course, that was in '83 and people didn't lock their doors and windows at night...

Hope some if this helps...

BTW @rusty_tlc gave you the formula for calculating CFM, above.

 

[williamghent]

We have a variety of options to ventilate your garage. Find the garage ventilation option that is right for you.

 

[firestopper]

Without insulation, no amount of air exchange will help in triple digit temps. Hot air out....hot air in. A swamp cooler would also help during the dry months.

 

[toyotaspeed90]

As others have said... there are a lot of vents - but those really are meant to help keep the temps manageable in an insulated attic.... it's the main reason a house is able to be climate controlled so much better than an unfinished garage.

My garage is partially finished (no insulation/drywall in the ceiling) - even in our lower climate and the fact that we have trees blocking the sun 60% of the day - and has a ridge vent and a vent in one the side of the house - and it also barely helps when the garage door is open - it will still get significantly hotter in the garage than both in the house and outside - which is because there's a huge black roof that's just soaking the heat from the sun right up.

My last house/garage was not finished and had the exact same issue.

 

[47coeman]

When I built my shop I put in extra large gable vents to accommodate the venting of extra air along with the vents along the roof line. The shop is 816 sq ft but I installed a whole house fan that is sited for a 1800 sq ft application. The shop is fully insulated with 19 walls and 39 ceeling. It does pretty good in the winter keeping it warm and cool till about 95 in the summer. However what is great in the evening I can cool it down quickly with the fan blowing out the attic quickly with the whole house fan. I recommend that if you are going to build that is a must being able to vacate the warm air when needed.