Keeping humidity out of the garage

[bigredbird]

I've been running a dehumidifier in my garage so that my '72 doesn't drown (and rust) in the summer air moisture here in the great swamp of Michigan. Water used to pool on the floor on really humid days, to the point where I'd have to break out a mop to soak it up. Now the garage stays dry, but it gets damned HOT in there with the windows closed to keep the humidity out. Today it was 92 outside and 107 in the garage.

Is extreme heat just as bad for an old Mopar as humidity? Should I start thinking about sticking an A/C in the garage window to keep the car cool as well as dry? I'm wondering what the rest of you do to keep your rides safe and happy in the summer.

[wannadrag]

Walls and ceiling insulated?My shop usually stays about 10 degrees cooler then outside in the summer.

[bigredbird]

Walls, yes. Ceiling in progress.

[Cranky]

Concrete slab for the garage? If so, doesn't sound like it has a vapor barrier that was installed when it was poured. I live 9 miles from Galveston Bay and we have humidity in the 90% area especially in the evening and over night and my slab never sweats. I think you can paint the slab and that will help. I did mine many years ago but it also has a vapor barrier that was laid down when the concrete was poured.

[bigredbird]

Yep, a slab, and it's painted, but humidity can bubble the paint right off. I have one of the 50,000 cookie-cutter houses that were built all over this town. Weird thing is, the garage is built of 2x6's even though 2x4's were code. All that extra strength, but the builders cheated on a frickin' vapor barrier.

So, does anyone else have an A/C'd garage?

[Donny]

Hey Cranky, when we do this deal, for sure, since you're so humid down there, best paint your car here in epoxy primer with sealer for piece of mind when you bring it home.

[Mopars & Missiles]

.....So, does anyone else have an A/C'd garage?

Yeah, but its more for ME than the cars.

[ws27]

The humidifier is what is making the heat. You have a compressor and fan that are using a lot of energy to remove the moisture. Honestly, 107 won't hurt the car, but might not be so great for the garage and/or you. If you use an ac window unit it will use the same amount of energy if you can use it to regulate just the humidity in the garage. Problem is, ac units are temp dependant. So you will be over cooling in order to dehumidify. Using more energy.

If you want to go nuts, you can get a humidstat to turn on a relay to turn on the window unit. You'd have to wire it up your self. Or just live with the heat for a few days.

When I'm done with my garage. I'm going to use a split ac system controlled by either a humidistat or thermostat. They make them now, but they are pretty expensive. That way, I can choose either.

[detmatt1]

Finish insulating the ceiling, that should help your cause. is the attic space properly vented? If not ad the proper venting. A couple of gable vents or a ridge vent in conjunction with one of those old school whole house fans that you mount in the ceiling that circulates air up into the attic would also help. You need to keep the air moving in there and it will stay drier.

[CtownChris]

How about and exhaust fan. Like in the attic of your home. Even a box window fan may move the hot air and humidity out. Cheaper then a dehumidifier I bet.

[68chicken]

When I built my shop I installed a 2 1/2 ton heat pump / ac unit with LPG gas backup heat. The thing is , I hardley ever have to use the a/c because two of the exterior wall are dug into the side of a hill. Also have good shade trees above. I like the gas backup , because I usually turn heat down to 50 or so if I/m not out there. But when I come in on a cold day the Gas backup brings it up to temperature fast , then the heat pump takes over for better efficiency.

[wannadrag]

Been doing concrete work for 30 years and very rarely do they use any vapor barrier up in the midwest from what i have seen.I lived in Florida for 6 months back in the mid 80s and we did use it there.

[Sonny Black]

I use fans to keep air moving & a roof vent
hope this helps,

Happy 4Th....
never forget,


Sonny

[Cranky]

Been doing concrete work for 30 years and very rarely do they use any vapor barrier up in the midwest from what i have seen.I lived in Florida for 6 months back in the mid 80s and we did use it there.

I started working in the home construction business in 65 and saw many slabs go down without a barrier but it wasn't long after when it was added. The house got it but even a garage that was a attached didn't but that also changed after a short time...at least in this area it did. The Houston area is just too low and close to the water not to have it.

[dfarmercse]

Here in SW Louisiana we put down vapor barriers, if not the slab will sweat.

Dave F

[bigredbird]

Thanks all. I've got a ceiling fan going in the garage, along with three cap vents. Unfortunately the shade tree out front only stretches over about 1/5 of the roof and the rest bakes in the sun all day. Think I'll start with a good window fan set to pull air out and see how that goes.

[Ron 73]

A window fan pulling the air out should help a lot, using one in my granddads garage for the same reason (24x24) and combined with a ceiling fan dried it up significantly. Good luck.

[65 Plymouth Satellite 426]

My Garage is Air Conditioned...Just Like The Rest Of The House!

[kdtjb]

An air cond. dehumidifys the air to a point. So if you add A.C. your dehumidifyer should run less. I don't know if the energy usage would be a wash, but it wouldn't be like running both all the time. But you the better you are insulated, the better it will work.

[bigredbird]

^ Finishing the ceiling insulation will be my next project as soon as it quits being 150 degrees up there... like, maybe, December.