Help me keep my garage cooler!

[P1et]

One of my first posts!

My wife and I purchased our first home about three years ago. I didn't come with a garage, and of course I had a nice 22x18 detached garage built. I will post a seperate thread on the build process.

I would like some assistance in keeping my garage a bit cooler without going the AC route.

I have an 18 foot insulated garage door, but that's about the only insulation in the structure. I have two windows in the rear of the garage, and an attic that leads up to a sizeable "room" upstairs.

We've had some very hot weather recently in Texas, hotter than usual. I want to help keep the place a little cooler, or even prevent it from heating up so quickly.

Who has any ideas?

 

[csp]

The obvious choice is insulation.

What we don't know is if you have open stud bays to install insulation.

Lots of threads on the subject, especially in the heating/cooling forum.

 

[P1et]

I cannot insulate the garage itself as I have drywall, and it's fully painted.

However, I can insulate the attic. Perhaps someone can give me some guidance there? I don't want to do any spray insulation as I use the attic as storage (we don't have storage in the house itself).

 

[VWandDodge]

I cannot insulate the garage itself as I have drywall, and it's fully painted.

However, I can insulate the attic. Perhaps someone can give me some guidance there? I don't want to do any spray insulation as I use the attic as storage (we don't have storage in the house itself).

?? Insulate the attic and then floor it.

 

[RascalRider]

Spray the underside of the roof decking.

 

[BigAl62]

Insulate what you can and get vent fans for attic space, they work great at lowering temps.

 

[Falcon67]

I cannot insulate the garage itself as I have drywall, and it's fully painted.

However, I can insulate the attic. Perhaps someone can give me some guidance there? I don't want to do any spray insulation as I use the attic as storage (we don't have storage in the house itself).

If you mean also no insulation in the walls, well... Good luck. Walls easily get 100+ with sun exposure and the roof deck will hit 140F~160F. Insulate your attic space between the joists - rip up the floor up there if necessary to do it. If nothing in the walls, plant trees or see a contractor about blowing insulation into the walls, then repairing and painting the drywall.

If you are new to Texas, then I can tell you we got hot quick this year and stayed hot. But late July, August and September easily have plenty of 100F+ days as a norm - depending on your location in the state. I'm 160 miles west of Fort Worth and we are hot anyway. If you want to work out in your garage during the summer days, you'll figure out how to insulate. My old shop (20x24) was insulated with R13 batts between the joists and in the walls. I had big gable vents and the west facing roof would run 150~160F under the deck in summer and the west wall 90F+ on the back side of the insulation without any cooling.

 

[stafford]

THere are people that can blow insulation into your walls, and in your ceiling, that's one way, then put an inexpensive window unit in and turn it on. I put a 15,000 btu in a 20 x 28 and it'll freeze the boys right off.

 

[trythis]

search the heating ac section of the forum. turd loads of info of options, info etc.

 

[soob]

Blowing insulation into walls is cake. I've done it before and I don't know anything about anything. Just get a 2 & 1/8" hole saw and some PVC pipe to make an adapter for the blower. Drill the holes at the top of each stud cavity and fill those suckers up with cellulose. It's messy but it works. The big box home improvement stores will rent you the machine for free with a minimum insulation purchase (about $200). Plus you can get a tax credit!

When you go to patch that drywall get a slightly larger hole saw (2 1/4?) and use it on a scrap piece. The larger cut outs will fit int your holes easily.

 

[69f100]

windows help, box fan, and a small window. crank it at night, enjoy it during the day

 

[gesoffen]

Not that it actually lowers the temp but a ceiling fan would certainly make it more comfortable through evaporative cooling. I have one in my garage and its made a difference. Also helps keep the mosquitos away by keeping the air moving.

 

[P1et]

Thanks for the help so far everyone. Looks like I'll be making a trip to Home Depot and picking up some R30. This should do the job:

http://www.homedepot.com/Building-Materials-Insulation/h_d1/N-5yc1vZasbsZ1z0zycl/R-202585885/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Also bought one of these: http://www.amazon.com/Lasko-Pro-Performance-Blower-4900/dp/B001DNGSCM/ref=sr_1_2?ie=UTF8&qid=1312383047&sr=8-2

Question: the R30 will obviously go under the floor and between the joists in the attic. Does it make sense for me to insulate under the roof decking as well? And do I need R30 for that, or can I put in a lower R rating and that be OK?

 

[csp]

Do you have room for R30? It needs a 9.5" deep space (2x10s). If you compress it you're lowering the R-value and wasting money. Fiberglass R-values are based on a certain amount of air space and "fluff".

 

[bigdav160]

What works up north doesn't work down here. Without A/C it's not going to get colder.
We have this discussion all them time around here.

With overnight temperatures in the 90's (bottoms briefly at 80º just before sunrise) the air is hot, the ground is hot, the slab is hot, the garage is hot and the insulation is hot.

The best thing to do is install a radiant barrier if the roof is in the sun. That will reduce the heat gain immensely.

Oh, and get a fan

 

[VWandDodge]

What works up north doesn't work down here. Without A/C it's not going to get colder.
We have this discussion all them time around here.

With overnight temperatures in the 90's (bottoms briefly at 80º just before sunrise) the air is hot, the ground is hot, the slab is hot, the garage is hot and the insulation is hot.

The best thing to do is install a radiant barrier if the roof is in the sun. That will reduce the heat gain immensely.

Oh, and get a fan

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 ****.

 

[bigdav160]

No ****.

What's your source for cooling in the garage?

Insulation does not have any magical cooling properties.

edit: These conversations remind me of the Lowes commercial where the guy is installing garage door insulation near his Hybrid Tahoe truck. They then go on to say"how much money he's going to save".

Unless he is heating or cooling the garage he's not spending anything to save!

 

[P1et]

I didn't think about the thickness or the R30, good point. I should probably measure and see how much room I have to accomodate insulation.

I'm not heating or cooling, but I would at least prevent the garage from heating up as quickly as compared to not having any insulation whatsoever, right?

 

[ChristopherLutz]

I agree with my fellow texans - unless you insulate AND run HVAC into your garage...it's just going to be uncomfortable for a couple of months. I'm in my 7th summer in Texas and I hate it more each year.

Still can't figure out why kids are off during July and August.....they're stuck inside...I'm stuck inside....

Summer in TX is the pits.

 

[rickairmedic]

I am not in Texas but the current heat index here in Louisville is 106*. I am out in the shop as I always am when home unless I am sleeping. I have an old furnace squirel cage pointed at me right now and I am not sweating granted I am sitting on my **** infront of the TV and laptop but the fan does work .


Rick

 

[fattogatto]

Dehumidifier

 

[Virgil Cain]

If you can put in a ridge vent (as much as possible) that will help. Then ceiling fans and shop blowers. But in Texas this time of year you're just moving 100+ F air around. Shade trees are a good idea but they come with the downside of possibly dropping on your roof at some point. If your windows face south or west you want white blinds to reflect as much light back as possible. Shade trees that shade at least the south and west walls will help, and you can position those to shade those walls without overhanging the garage.

BTW, you can put expanding insulation in your walls without taking the drywall down. If you put it in at the very top of the wall you can hide the holes behind trim molding. Or, if you have easy access to the top plates of the walls you can put it in through there.

None of this is going to help as much as a fairly small and inexpensive window AC unit. Window unit AC + insulation will be best.

A dehumidifier is an AC unit without the cooling ability. If you're thinking that direction you might as well go with an AC.

 

[P1et]

So after some more research on this forum, looks like this might be a good plan:

1) get a ridge vent installed
2) install rafter vents
3) install R13 and do the roof decking
4) install R13/R19 and put that between the exposed ceiling joists

 

[Virgil Cain]

I think if you do all that it will be much better, but I still suspect that it will be very unpleasant this time of the year during the heat of the day. Just out of curiosity, is the reason you're staying away from air conditioning a cost issue or an aesthetics/home owners association issue?

BTW, if you put insulation under the roof decking, are you still going to have some open airspace under the roof for the ridge vents to work?

I'll tell you a personal experience with ridge vents on my house. It was built 10 years ago and had three powered mushroom fans on the back roof. We had to replace the roof fairly early for a couple of reasons and the roof installer suggested a ridge vent system. I couldn't be happier with the results. Our electrical bill which is dominated by AC in the summer has been about $100 cheaper per month versus last year and we've had a rate increase since and the outside temperature has been equal or higher than last year. My upstairs AC is running much less often than it did with the powered mushroom fans.

 

[P1et]

I'm staying away from AC for the reasons you mention above, minus the HOA issue. I don't work in my garage, so it doesn't need to be 75 degrees in there, but if I can keep it between 90 and 100, it'll have been worth it. I also cannot insulate the walls.

I test fit some R13 under the roof decking, and it looks like if I staple the R13 flush with the joists, then I'll have at least an inch between the roof decking and the insulation. At home depot I found the rafter vents, so I can always buy those as well, which I most likely will as they are quite cheap.

I've started on step four yesterday, and quickly put down 4x18 feet or R13 batts. Very simple and tidy job!

 

[VWandDodge]

I'm staying away from AC for the reasons you mention above, minus the HOA issue. I don't work in my garage, so it doesn't need to be 75 degrees in there, but if I can keep it between 90 and 100, it'll have been worth it. I also cannot insulate the walls.

I test fit some R13 under the roof decking, and it looks like if I staple the R13 flush with the joists, then I'll have at least an inch between the roof decking and the insulation. At home depot I found the rafter vents, so I can always buy those as well, which I most likely will as they are quite cheap.

I've started on step four yesterday, and quickly put down 4x18 feet or R13 batts. Very simple and tidy job!

Why can't you insulate the walls? Every little bit will help, and believe me, 100º is not a comfortable environment for working in a garage.

 

[P1et]

The walls already have the drywall hung, and painted the way I like it. I'd hate to rip it out it any way, shape or form... The garage door is insulated, the other three are not.

 

[fattogatto]

I'm staying away from AC for the reasons you mention above, minus the HOA issue. I don't work in my garage, so it doesn't need to be 75 degrees in there, but if I can keep it between 90 and 100, it'll have been worth it. I also cannot insulate the walls.

I have a $90 dehumidifier in Memphis. 2400 square feet - 10 foot ceilings. 100 degrees outside means 88 inside - I leave it running 24/7 and plumb the outlet hose to a drain. I am also curious why you can not insulate the walls.

 

[VWandDodge]

The walls already have the drywall hung, and painted the way I like it. I'd hate to rip it out it any way, shape or form... The garage door is insulated, the other three are not.

OK, I'm positive someone stated earlier than a small hold can be cut up high and insulation blown in, after which the hole can be patched. By only having an insulated door and ceiling is akin to running the A/C with a window open -- it defeats the purpose. You'll be better off in the long run, and far more comfortable, by going that route. Besides -- it's a garage The walls don't have to look super pretty.

 

[P1et]

It boils down to what I am comfortable doing myself vs. having to pay someone for. I can easily put down insulation in the attic myself. However, if I start cutting holes in the drywall, having to blow in insulation, then patch the holes and repaint them, I'm afraid I'm going to really screw things up.

And my walls are looking pretty now, not sure if I want to start hacking it up:

 

[FatFenderBowTie]

The option is insulate and have a building you can use, don't insulate and have a building you won't. Even with any minor imperfections from the hole touch ups after insulating, I would rather a building I will go into rather than a pretty one I won't.

 

[Virgil Cain]

The walls already have the drywall hung, and painted the way I like it. I'd hate to rip it out it any way, shape or form... The garage door is insulated, the other three are not.

You can put two part liquid expanding insulation in the walls. If you have access to the top plate of the walls you can drill a hole every 16" (assuming your studs are on 16" centers") and install it there and you'll not have to disturb the walls at all. This type of insulation is used all the time to retrofit insulation into homes with no insulation in the walls. We used it on my parents home which was built in the 1950's with zero insulation in the walls.

 

[wolflrv]

And if it's a really tight squeeze to get to your header plates to drill, you'll want to look at a product called a D'Versibit. Just do a Google search. We had to drill holes in very cramped spaces to pull wire all the time. The D'Versibit will let you do that it easily.

I agree though with what everyone else has said. My shop currently hits 115 degrees right now in July and I'm working hard every morning early for about 2 hrs to finish the insulation and button up the shop so I can run my AC. It's deadly out there right now after about 10am in the morning.

 

[NUTTSGT]

Does your garage have vinyl siding ? I suppose you could pop off the top piece and blow the insulation in from the outside.

 

[Virgil Cain]

Does your garage have vinyl siding ? I suppose you could pop off the top piece and blow the insulation in from the outside.

That's actually an excellent suggestion. If you don't want to do polyurethane or isocyanate insulation and you have vinyl siding you can easily take off one of the upper courses of siding and drill holes from the outside and blow in cellulose insulation, then close up the holes and then put the siding back. This is very commonly done, and you can easily do it yourself.

 

[bigdav160]

Good luck with all that. Most people around here don't understand how insulation works.

If you don't work in the garage what difference does it make if its 90º or 100º?

 

[Virgil Cain]

Good luck with all that. Most people around here don't understand how insulation works.

If you don't work in the garage what difference does it make if its 90º or 100º?

I understand how it works. I'm just hoping that after he insulates it and finds that it's still to hot to work in that it will be well insulated enough that it can pop an cheap window A/C in and he can cool the temperature easily. I think if he insulates the ceiling and walls decently that a $400 A/C window unit will cool that sized shop easily (something around 18,000 BTU give or take).

 

[billcole]

One thing I do sometimes is run two window fans at night. One running as an intake and one as exhaust. The next morning I will shut the windows when the outside temp starts to go higher then inside. My garage is well insulated so it maintains the low temperature for most of the day. Another suggestion is to keep the car/truck outside when you get home if you plan on working in the garage. Its amazing how fast a vehicle that has been running and outside will heat up a garage. I have ceiling fans but I am still up in the air on how affective they are. My garage is 11.5' on the inside and I sometimes thing the fans are moving the hot air down. Also keep your windows blinds shut during the day. I was doing some research one day about cooling a garage down and I remember seeing a set up where a guy set up a water misting system for his roof to reduce the attic temp which helps the inside temp.

 

[SGKent]

our garage is fully insulated above and in the walls, drywalled and the garage door is insulated. It is bearable on summer days. It is hot at night as the heat soaks thru. BUT having lived in the Central Valley of California for 20 years, NOTHING short of A/C is going to really cool it when it is humid and 106F outside for a week unless you like heat. If you don't want something permanent get one of the units that has inlet and outlet air in a hose. Then use fans in the garage with it to keep the air circulating. Adding insulation will help slow the heat soak. If you can stand the heat outside in the shade then simply putting one big fan blowing in and one blowing around will help.

 

[71flh]

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

BTW, going in the attic in the Texas summer isn't recommended for sane people...