Help me keep my garage cooler!

[Ocho]

I'm in Texas, where it will be a nice 106 in the shade today.

I believe the OP was simply trying to make his garage cool enough to go get something without having a heat stroke. Nothing is worse than to be clean and showered and have the wife ask you to hang a picture. Just walking into the garage to get a hammer and a few nails can sweat soak your shirt.

A few things I do when I know I'll need the garage:

• I don't pull the cars in right after I get home from work. It just brings in more heat. Sometimes I'll even leave them outside all night. This makes about as big a difference as anything.
• Leave the garage door up by about six inches and the attic stairs open to promote some ventilation.
• Use a fan while working. I have experimented with blowing the fan across my work area for an hour or two before I start, but I can't tell if it helps or not.
• Put off major projects until October. Seriously, the heat we have right now will hurt you. If you don't HAVE to be out there, don't be out there.

This time of year EVERYTHING is hot - tools, walls, even the soap in the soap bottle. We took a laser thermometer around our shop at work this week and the floor was 106, the walls were 120 on the west side, the back seat of a car sitting in the parking lot all day was 175(!).

Stay cool, y'all!

 

[Brad1234]

I work with a guy that has an insulated garage & runs a dehumidifier 24/7 in the summer. He says that if he keeps it closed up it's not too bad out there.

 

[NUTTSGT]

I blew in insulation above my garage ceiling last July and it makes a huge difference. The garage stays relatively cool until the afternoon.

Damned straight my friend. I dropped and insulated the ceiling with R19 last fall, the garage stays about 12-15 cooler than the outside now.

You need to create an "attic" space and insulate it, this allow a place for the hot air to vent itself out.

 

[P1et]

Thanks for all the input so far guys, it's much appreciated.

I was able to put down R13 between the attic joists on half of my garage. I've been keeping track of the temperatures on a daily basis to see if a difference is being made. I have a digital one under the roof deck, and two on my cabinet.

The temperatures under the roof deck range anywhere from 86F to 145F. Before putting in the R13 (remember, I only have done half so far) I was reading a consistent maximum of 108F in the garage itself. After the R13, I maxed out at 102F.

I'll report back once I complete the second half of R13 between the attic joists.

 

[NUTTSGT]

You're making headway, congrats. Do you itch ?

 

[BTC]

The insulation is lowering the temps? Does the insulation understand how it's supposed to work?

 

[P1et]

Today the temperature touched a maximum of 100F. Temperature in the attic reached 142, so that makes sense. Temperature in the attic the day before reached 144, with 102F in the garage.

And yes Eric, I did itch. I made the mistake first time to wear a t-shirt and shorts. Didn't make that mistake the second day!

 

[P1et]

You're making headway, congrats. Do you itch ?

Yep! The temperatures in the garage today didn't go above 100F. Progress indeed!

The insulation is lowering the temps? Does the insulation understand how it's supposed to work?

I am trying to prevent the head from the attic to come into the garage. I would assume that since not as much heat is coming down as before (I only have half of the attic ceiling covered with R13 now) I would assume that's attributing to the ~6F drop in garage temperatures.

I am hoping once I cover the entire attic ceiling, I'll see some further improvement. Then, I'll start putting R13 under the roof decking.

It's actually been cheaper than initially though. With two "packets" of R13 from Home Depot, I can do the entire attic ceiling. That's just slightly more than $100...

 

[gesoffen]

I am hoping once I cover the entire attic ceiling, I'll see some further improvement. Then, I'll start putting R13 under the roof decking.

If you have a conventional attic/roof (aka cold roof), you don't want that insulation in direct contact with the roof deck as it will shorten the life of your roof system by effectively cooking it from both sides and preventing moisture/condensation from evaporating. You want ventilation in the attic (proper ridge/soffit vent system or similar) to allow air flow through the attic and along the roof deck to cool and evaporate moisture (and prevent ice damning if you're in snow belt climate).

There are ways to do what you want to do (effectively an insulated attic or "hot roof") but you'll need to use the eve baffles throughout the roof and/or go closed cell spray foam ($$$). At the very least, check with the shingle manufacturer to see whether a hot roof system will void warranties.

 

[xscorex]

like most guys here said insulation is the important part. I put in a 10,000 btu window unit in my two car garage thats not insulated. I can run for hours and it doesnt do anything. About the only thing its good for is when you get too sweaty you can stand in front of it for a few minutes to cool down. I dont have alot of money so I'm insulating one wall at a time. So far I have 1 wall down 3 walls and a ceiling to go Also Ive found the same thing applies to heaters. 3 kerosene heaters and its still freezing in there.

 

[VWandDodge]

Congrats that you've seen insulation makes a difference. You might call an expert to come out and assist with ensuring the roof is properly vented. I would avoid those POS power ventilators from the home centers as they are 115/120V. I installed one a few years ago and it burned out in short order. About 20 years ago, my dad installed a 230V large diameter fan in his attic complete with a wired in thermostatic control to turn it on and off as needed. The fan will help maintain an attic temp of 120º and will greatly extend the life of both the roof deck and the shingles.

 

[NUTTSGT]

The insulation is lowering the temps? Does the insulation understand how it's supposed to work?

Maybe not actually lowering temps but it will keep it from rising. Basically a play on words, nothing more. Is it proper to say it that way, maybe not but we know what he means.

 

[bigdav160]

Fiberglass insulation is not a radiant barrier. The OP would be better served by venting and installing a radiant barrier in the attic space.

The house next to mine is being renovated as part of a flip. Do you think the carpenters are hoping for triple pane windows and R50 instead of R19? No, they have every window and door open praying for some ventilation. They eat their lunch under a tree in the back yard. The insulation is not making it cooler.

 

[VWandDodge]

Fiberglass insulation is not a radiant barrier. The OP would be better served by venting and installing a radiant barrier in the attic space.

The house next to mine is being renovated as part of a flip. Do you think the carpenters are hoping for triple pane windows and R50 instead of R19? No, they have every window and door open praying for some ventilation. They eat their lunch under a tree in the back yard. The insulation is not making it cooler.

: rolleyes2 I'm betting insulated 2"x6" walls wouldn't make it cooler either, right?

I swear, you Oklahoma/Texas natives make me laugh.

 

[P1et]

Fiberglass insulation is not a radiant barrier. The OP would be better served by venting and installing a radiant barrier in the attic space.

The house next to mine is being renovated as part of a flip. Do you think the carpenters are hoping for triple pane windows and R50 instead of R19? No, they have every window and door open praying for some ventilation. They eat their lunch under a tree in the back yard. The insulation is not making it cooler.

I already have a radient barrier in the attic space. I'm seeing constant temperutures topping 144F under the roof deck.

Yes, a ridge vent would be a good idea.

 

[jeffk14]

Ever since I moved to Oklahoma some 20 years ago I've never understood the mentality of people here and in Texas. Where do you people get this "insulated buildings work up north but not down here" BS? Think of a refrigerator -- same concept. Insulation and thicker walls will indeed keep the heat down/reduced and will prevent the AC from working harder than it should.

Funny how, since energy prices have increased, people have been working like mad to insulate their homes and are discovering, "Wow! It has actually made a difference."

No ****.

: rolleyes2 I'm betting insulated 2"x6" walls wouldn't make it cooler either, right?

I swear, you Oklahoma/Texas natives make me laugh.

Your claims are correct only if you're talking about a heated/air conditioned space. Insulation ONLY slows the rate of heat transfer.

During the heat of summer, an insulated garage without A/C will take longer to heat up during the day, but after heating up for a few days, it'll also take longer to cool off at night. After several days-running of hot days and muggy nights, I doubt that insulation would make a whole lot of difference.

 

[bgarrett]

If I had a tiny garage like yours, the most obvious thing to do is prevent the sun from striking the roof or walls, You may have seen trailer houses with freestanding roofs above them. Thats the idea. Add walls with plenty of space for air to move freely and learn about earth tubes.

 

[Krash Kadillak]

For temporary relief, I'm wondering if a window-mount or portable swamp cooler might work for you? The cooled / humidified air should stay close to the ground, so your immediate area should be more comfortable, and it will feel alot better than just a big fan by itself.

 

[P1et]

I finished putting R13 between the joists:

Also bought a wicked fan:

Question: as you can see in the picture, I put a mock-up together of what it could look like when I put R13 close to the roof decking. My idea was to put it flush with the beams, so as to leave quite a bit of space between the insulation and the actual roof decking. Would this work?

 

[csp]

You just need a couple of inches to allow for air flow.

 

[dittle fart around]

Ventilation would be an extra help. A large attic fan on the gable end with thermostat might do it. My attic space above the garage has a small 110 volt fan and 12 inches of fiberglass batt insulation and is the coolest space in my house. The rest of the house has blown in insulation R-30.

 

[P1et]

Just wanted to thank everyone who helped me with this issue. We've had the hottest week so far in Austin (topping out at 111F yesterday) and the garage never made it above 99F.

Pleased!