Cooling Garage Workshop in the Southeast on the Cheap

[Patrick Harper]

My situation is a bit unique and I'm unsure of how to tackle it. My current shop exists in a two car garage in a house that faces south-southwest. The heat in the afternoon is brutal this time a year. The rear wall and about 2/3rd's of one side wall on interior walls. All of the walls and garage doors are insulated. There is a small attic space above the front face of the house (5ft x 22ft). That is the only portion of the garage that is uninsulated.

I don't currently have the budget for a mini-split and, from what I understand, the small portable units don't work well in high humidity. I'm considering insulating and/or installing a gable fan in the small attic space, but I'm not sure which one I should try first. The gable area has a small window which would need to be replaced with a vent. If I insulate the attic area, should I insulate the wall, the attic floor, or both?

Thanks in advance.

[Jim Andrew]

Insulate, insulate, insulate. And with insulation you must have ventilation. Insulation tends to collect moisture if it is not ventilated well. Especially in the humid southeast. If you have flooring in your attic for storage, I would be tempted to take it up and insulate under it, with the possibility of putting it back down. If you cannot get your insulation thick enough under the flooring, consider stacking boards on top of the existing joists to get the proper amount of insulation.

[Robert Engel]

I'll give you my opinion take it FWIW.

I live in NE FL and I can relate. Lately where I live its been in the upper 90's in the shade. My shop is in an old horse barn and uninsulated, but there is no direct sun hitting the walls and that makes a huge diff. I've been able to work in the afternoons a bit but when it hits 98 its just too darn hot. I can't imagine if I had the sun beaming in.

1) If most of the heat is coming from direct sunlight, then adding more insulation probably won't help much.
2) Its also not going to help much to put a fan in the attic (if that's what you're talking about) especially with garage door open. There would be a benefit to the rest of the attic, though. I have 2 attic exhaust fans in my house, one at each gable end.

IMO shade + fans is the answer for you.

Something like an awning or one of those metal carports off front of your garage will help. Even one of those collapsable tents or better yet, a roll out awning like you put on an RV.

I recommend one big fan blowing out and something like a pedestal fan. I mounted a 3' fan in a window blowing out on the other end of my shop.

....last but not least a small fridge stocked with cold beverages of your choice.

[Kent Adams]

Insulate, insulate, insulate. And with insulation you must have ventilation. Insulation tends to collect moisture if it is not ventilated well. Especially in the humid southeast. If you have flooring in your attic for storage, I would be tempted to take it up and insulate under it, with the possibility of putting it back down. If you cannot get your insulation thick enough under the flooring, consider stacking boards on top of the existing joists to get the proper amount of insulation.

If the roof is sealed as well as the ceiling, you don't need ventilation, in fact ventilation can cause a lot of problems. My shop has a "hot roof". There is no condensation built up from conditioning the air below the ceiling. http://www.buildingscience.com/documents/reports/rr-0108-unvented-roof-systems/

[Patrick Harper]

Insulate, insulate, insulate. And with insulation you must have ventilation. Insulation tends to collect moisture if it is not ventilated well. Especially in the humid southeast. If you have flooring in your attic for storage, I would be tempted to take it up and insulate under it, with the possibility of putting it back down. If you cannot get your insulation thick enough under the flooring, consider stacking boards on top of the existing joists to get the proper amount of insulation.

I'm assuming I should insulate the exterior wall section in the attic as well as the floor. There isn't currently anything on the attic floor, so insulating shouldn't be difficult.

[Patrick Harper]

Robert, unfortunately due to HOA regulations I cannot add any shade to the front of the house. That's also cost prohibitive for me.

[Andrew Ulsher]

What about a retractable garage screen?

http://www.stoett.com/garage-retractable-screens/

[Patrick Harper]

Interesting idea, but I'm not sure it would be better than an insulated door.

[Andrew Ulsher]

Insulated door would not allow air flow where a screen that has sun blocking properties will allow air flow with a combination of fans should maybe make it bearable.

I'm in the same boat right now, trying to figure out what to do to cool a garage.

[Patrick Harper]

It's a bear. I'm really curious as to whether an exhaust fan in the small attic space or adding insulation to the small attic space would be more effective...or if either are worth trying.

[Thomas Wilson]

A lot of your heat has to be radiating down from the ceiling of the garage. A IR thermometer like this one http://www.thermoworks.com/products/ir/irgun.html would let you see what walls temperatures are. You can check before and after your modifications to see how much good you did, too.

I would try to lower the temperature of the attic and separate the attic and the garage thermally to reduce the heat entering the garage. To lower the temp of the attic, I would put a fan in the gable end. Size the fan by the square feet of roof. I am assuming you have soffet vents to let air into the attic. To separate the attic from the garage, I would insulate the floor of the attic space. 10" or so would be good. Blown in insulation is pretty cheap.

[Steve Kinnaird]

I just checked into the Stoett Screens.
The local screen shop dropped them because the constantly fail and fell apart.
Might just buy some screen and set it up like a roll-up shade, using a PVC pipe and pulleys.

[Steve Kinnaird]

Those are great for detecting where heat is coming in.
Harbor Freight usually has them on sale for around $25 to $30 and you can use the 20% off coupon too :)

[Patrick Harper]

Thanks guys. I just bought a temp gun from Amazon. $15 and prime eligible if anyone's interested. http://smile.amazon.com/BAFX-Products%C2%AE-Infrared-Thermometer-INCLUDED/dp/B00NI3HNQK/ref=sr_1_12?ie=UTF8&qid=1434543855&sr=8-12&keywords=infrared+temp+gun

Not super high resolution or anything, but it seems to get good reviews.

[Andrew Ulsher]

Steve that is interesting about the Stoett Screens. I have not been able to go to a local shop to view any other options. I have seen a couple that are like a second garage door you can slide down as well.

Any idea what the cost was for the Stoett was? I'm debating a portable A/C unit by Whynter now. Might be able to get a used for $300, but I need to decide how to build a skirt for the garage or punch a hole in the exterior wall for the intake/exhaust.

[Patrick Harper]

Andrew, what's the humidity like in San Antonio? The portable units don't seem to work very well in the high humidity we have here. I've been considering a mini-split once all of my other options have been exhausted. I found a guy selling several new-in-box units for around $400/each, but I'm unsure of the brand. Supposedly, he won them in a recovery auction for pennies.

[Andrew Ulsher]

Humidity is about 40-50% typically with the exception of lately due to being pounded with rain. I thought mini splits start running up in the the $4-6,000 range?

If I can get a portable unit to get the garage down to low 80's and reduce the humidity a bit I would be happy. I'm not looking for a 70 degree shop just bearable.

[Steve Kinnaird]

Never got a price for the Stoett.
1 guy told me that he could get me a motorized unit by Progressive starting around $2,000
I am going to build channel boxes on each side of the roll-up door and build a roll-up screen using a PVC pipe and fiberglass screen. It will work like the roll-up sun shades that they have on screen porches. Should cost less than $100 for everything.

[Patrick Harper]

Humidity is about 40-50% typically with the exception of lately due to being pounded with rain. I thought mini splits start running up in the the $4-6,000 range?

If I can get a portable unit to get the garage down to low 80's and reduce the humidity a bit I would be happy. I'm not looking for a 70 degree shop just bearable.

Not for the typical 9000-12000 btu units you'd use for a small 400sq/ft garage like mine. Most are about $1000 new. Some can come with precharged lines and you can install yourself. I wouldn't imagine you'd spend more than about $1500 for a small unit installed. Still expensive though. I'd rather spend that money on tools.

[Patrick Harper]

315849

This is the front wall of the attic area above the garage that gets direct sunlight during the afternoon. I'm thinking of trying a roll of the radiant barrier stuff. That wall is pretty darned hot to the touch and I think it's a major contributing factor. The air temps have to be above 120 in there when it's in the low 90's outside.

[Walter Mooney]

I have to agree with Mr. Wilson -- start by lowering the temp in the attic and separating it thermally from the garage. And IMHO, you can't beat radiant barrier materials for that. Google "foam insulation boards with radiant barrier" and you'll find a link to a Johns-Manville product. Buy a few sheets of that and apply them to the attic wall and maybe even to the underside of the roof rafters. Just make sure the radiant barrier side faces out or away from you. Measure the temp in the attic before you install it and the day after you install it. I'll bet you'll see at least a 20-degree drop in the temp in the attic.

My $0.02

[David Ragan]

Dude-Suwanee is just down 141 from me, and it was really hot today.

HOA doesn't allow anything tacky on front of house, but away from the street, on the back we finally put a window unit in the Master BR---really great.

What you're battling is plain physics. Block the energy from coming in, get the air moving--

[Nathan Callender]

Well, I've thought about this a lot over the years and came to the conclusion that in the south, some times it's just better to not fight the heat and spend more time at the pool during the summer. :)

That said, with a fan and open garage door and once the sun is setting, it can still be hot but way more manageable than at 5pm.

[Patrick Harper]

Dude-Suwanee is just down 141 from me, and it was really hot today.

HOA doesn't allow anything tacky on front of house, but away from the street, on the back we finally put a window unit in the Master BR---really great.

What you're battling is plain physics. Block the energy from coming in, get the air moving--

Very cool! You should come to the monthly MWA breakfasts at the Peachtree Diner in Roswell. Very informal breakfast and a great group of guys.

I'm in the same boat regarding the HOA. It makes me never want to live in a neighborhood again.

[Patrick Harper]

I have to agree with Mr. Wilson -- start by lowering the temp in the attic and separating it thermally from the garage. And IMHO, you can't beat radiant barrier materials for that. Google "foam insulation boards with radiant barrier" and you'll find a link to a Johns-Manville product. Buy a few sheets of that and apply them to the attic wall and maybe even to the underside of the roof rafters. Just make sure the radiant barrier side faces out or away from you. Measure the temp in the attic before you install it and the day after you install it. I'll bet you'll see at least a 20-degree drop in the temp in the attic.

My $0.02

I definitely think this is the way I'll go. I'm just not sure if doing the wall alone will suffice or if I'll need to do the room as well. There is ridge and soffet vents up there, but it's still hot enough to cook an egg.

[David Ragan]

Very cool! You should come to the monthly MWA breakfasts at the Peachtree Diner in Roswell. Very informal breakfast and a great group of guys.

I'm in the same boat regarding the HOA. It makes me never want to live in a neighborhood again.

I must say I'm all socialized out @ the end of my day and week, but what is the MWA?

[Julie Moriarty]

We're down in Florida right now where the daytime temperatures hover in the mid 90s. When in the sun, it seems like you're in an oven.

We've looked at some houses and I've been trying to imagine using a garage for the workshop. One house had the overhead garage door opening screened, obviously intended for ventilation when working in the garage.

So far, I can't see anything outside of air conditioning that would make the garage comfortable during the summer. And when you factor in what the heat and humidity could do to the wood, it seems an unconditioned garage would wreak havoc on woodworking projects.

[Steve Kinnaird]

Where are you looking in Florida?

[Jim Dwight]

The ways heat flows is by conduction, convection and radiation. Conduction is when your attic is hot, your garage is sealed from it, and the thermal energy has to move through the ceiling and any insulation to make the shop hot. More insulation slows this down. R-30 is required in my area for ceilings. Convection is when you have a way for air to flow between your hot attic space and your shop. It is MUCH more efficient in transferring energy than conduction. This is why you need to seal the attic from the shop. Radiation is how the sun transfers energy to us. It is a function of the temperature difference to the fourth power. If you can reflect the sun's energy off the house (reflective roofing) it will help. A radiant barrier in the attic will do very little because the temperature difference between the hot roof and the interior spaces is too small.

Seal cracks and insulate. Fan will help mainly if you pull in cooler night air then seal it up. Little window unit will help a lot if you seal it up and insulate.

[Julie Moriarty]

Where are you looking in Florida?

We were looking in Punta Gorda. We just got back last night. The difference in temperature and humidity from there to here is pretty dramatic. My workshop is in the basement and I can control the temperature and humidity fairly well. The homes we're looking at are half the size of the one we now have and don't have basements, so the garage is the only place to set up a workshop. Every garage I walked into was hot and humid. Many smelled musty. I can only imagine what that would do to your hardwood stock. I'm thinking the humidity could be a woodworker's worst enemy. Take a piece you finished in a hot and humid garage and bring it into an air conditioned environment...

[Steve Kinnaird]

Nice area. Had a friend that lived in Punta Gorda.
Yes the humidity is very much part of living in Florida.
It will pour down rain and then be in the 90's and you feel like you are walking through a wall of water.
Good luck with the home search. Get a BIG garage :)

[Patrick Harper]

I must say I'm all socialized out @ the end of my day and week, but what is the MWA?

Modern Woodworkers Association http://www.meetup.com/Modern-Woodworkers-Association/

[Patrick Harper]

A radiant barrier in the attic will do very little because the temperature difference between the hot roof and the interior spaces is too small.


I think you might be wrong about this one. My hot roof is 135+ degrees. The ambient in the attic space is about 120, and the ambient in the shop varies from 80-90. The insulated walls of the garage are around 80 degrees most of the time during the summer. The attic ceiling is about 97. I couldn't imagine reflecting the heat from the 135+ degree attic roof wouldn't bring down the temps in the attic.

[glenn bradley]

Robert, unfortunately due to HOA regulations I cannot add any shade to the front of the house. That's also cost prohibitive for me.

That's unfortunate. Just to add some credence to the shade argument, the patio cover along the south side of my home drops the interior temp by 10 degrees. this is one of those things that is not subtle; you don't have to concentrate to feel the difference, it is significant.

[John Lifer]

You do realize that you have two inversely related desires? Cooling and cheap are pretty much exclusive of each other. Can't get cheap and have cooled shop, will cost you one way or the other.

I'd insulate as much as possible in the attic. Is the cheapest fix to get toward cool... Get an air conditioner and get on with it

[Robert Engel]

This is my shop a couple days ago:


316235

Its been in the high 90's for almost 2 weeks so I'll take 80-90 degrees all day long!!!

[Maurice Ungaro]

Patrick, when I lived in Beaufort, SC, I insulated my shop with Isonene spray foam insulation - walls and ceiling. It was an 18 x24 unit, with vaulted ceiling. I punched a hole in the back wall and installed a window unit. Worked amazingly well. Then of course, my wife would open the garage door for some flippin reason, and let all the cold air out! Seriously, check it out as an option.

[Patrick Harper]

This is my shop a couple days ago:


316235

Its been in the high 90's for almost 2 weeks so I'll take 80-90 degrees all day long!!!

Yikes. At least the humidity isn't 80%+ like it's been here for the last few weeks. I'm starting to think that just keeping the humidity down would make it a lot more bearable. It hasn't been getting more than about 85 degrees which leads me to believe that the insulation is doing a pretty decent job despite the garage door constantly being opened.

[Patrick Harper]

I believe that the radiant barrier is helping. I'm guessing that temps are down about 5 degrees from where they were, but the temps outside are down. It's just a guess.

I'm considering buying one of the small portable AC's and venting under a garage door or into the attic space. They don't have the best reputation, but most also dehumidify. I figure if it doesn't work out, I could easily return it after a day or two. I'd still love to do a minisplit, but it's just not in the budget right now. Don't know how much longer I'll be in this house. If the portable unit does an okay job, I could take it with me when I move.

[Michael Weber]

I have to agree with Mr. Wilson -- start by lowering the temp in the attic and separating it thermally from the garage. And IMHO, you can't beat radiant barrier materials for that. Google "foam insulation boards with radiant barrier" and you'll find a link to a Johns-Manville product. Buy a few sheets of that and apply them to the attic wall and maybe even to the underside of the roof rafters. Just make sure the radiant barrier side faces out or away from you. Measure the temp in the attic before you install it and the day after you install it. I'll bet you'll see at least a 20-degree drop in the temp in the attic.

My $0.02
I have a question about the statement "Just make sure the radiant barrier side faces out or away from you". Does it really matter? I have always understood it doesn't matter which way it faces but that it is imperative there must be an airspace between the reflective side and any surface it faces. Have I misunderstood?

[Patrick Harper]

I have a question about the statement "Just make sure the radiant barrier side faces out or away from you". Does it really matter? I have always understood it doesn't matter which way it faces but that it is imperative there must be an airspace between the reflective side and any surface it faces. Have I misunderstood?

Michael, the stuff I bought is reflective on both sides, so it doesn't matter. There are some that are only reflective on one side. If you live in a colder climate, you might want the reflective side facing in, to keep the heat in. In a warmer climate, you'd want to reflect the heat back out.

[Duncan Foster]

Hi Patrick. I live in South Florida and mini split does a phenomenal job removing humidity and cooling. Pricey yes. I got a Mr. slim unit from Ecomfort.com. Easily saved a couple of grand. Found a local electrician to install it for me., pulling the appropriate permits etc. The prices local company to purchase and install We're just too high.

[Alan Lightstone]

I have the combination of insulation, solar attic fans, and a mini-split system. Certainly not cheap for the combination, but absolutely works effectively in South Florida.

The solar attic fans were cheap and work very well.

[Rick Potter]

When you finish isolating and insulating, I would check CL for a large used window or through wall AC unit. That is probably as cheap as you can go and be effective.

[Charles Lent]

When trying to cool an area with an air conditioner, the unit must first reduce the humidity before it can bring down the temperature. Lock the garage door so she can't open it and it will have a chance at lowering the garage humidity. Once the door is opened, all that nice dry, and cool, air will be lost and it will have to start all over again. Insulate to the best of your abilities and install an air conditioner. window, mini-split, or whatever, but work hard at keeping the humidity out so your air conditioner has a chance of working well. If she opens the door it will likely take a 1/2 day to get comfortable again.

My shop is a 1 car size detached building. It has 3 1/2" fiberglass in the walls and 6" in the ceiling. I have a 1.5 ton window style heat heat pump mounted high in the North wall and the shop is located near Charlotte, NC. In this 90-100 heat that we've been having every day I have to turn on the AC very early in the morning or leave it on 24/7 in order to keep the temp below 80 deg. The humidity remains in the 40-45 % region inside the shop when the AC is running. I do my best to keep the doors shut as much as possible this time of year too.

Charley

[Alan Rutherford]

...So far, I can't see anything outside of air conditioning that would make the garage comfortable during the summer. And when you factor in what the heat and humidity could do to the wood, it seems an unconditioned garage would wreak havoc on woodworking projects.

Also on all the tools. I pick up something when the temp and humidity are both over 80 and it feels damp. And then there's Winter. I have stuff rusting in my Florida garage that survived decades in the rainy Northwest. You can neither heat it, cool it or dehumidify it unless you can close it up.

I had one of those portable AC units that I paid about $40 for at a thrift shop and it was worth that. Thing is, you could duct it outside with some effort but that air came from the conditioned space. It would work better with an intake as well.

For the money, I'd get a window unit and if you can't put it in a window, build a frame of some sort and direct the cooled air one way and the heated air the other.

All the advice about radiant heat and ventilation is good, too.