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Every spring, when the temperature swings up quickly, if I open my garage door (letting in the warmer, moister, outside air) TONS of water condenses on the garage floor. Lots of it. Little rivers run accross the floor.
This is not the way I remember other peoples garages behaving. Yes, there should be condensation on the cold floor. But this is alot.
Has anyone out there experienced this and what did you do about it?
I have confirmed that the moisture does not percolate up from the ground and I have also confirmed that as soon as the floor warms up (may take several days) this stops. Right now I suspect that there is some kind of coating on the concrete surface the previous owner put down that prevents the naturally condensing water from just flowing down through the concrete.
Anyway, this is bad because any thing stored in this garage gets SOAKED every spring (usually several times, as the weather in SE Michigan swings back and forth all winter and spring). I hope someone out there’s got a good idea for me…besides “not opening the door” 🙂
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Keep the door closed. Heat the garage and keep above freezing. Place a ceiling fan in garage and run on occasions like this. Just kidding.
Do you keep excess water and salt off floor? Salt will bring in ten times its weight in water and leaches greatly. How is you drainage inside and out? should slope away. Are you sure that it's not coming from below, that seems most likely as a common cause.
*Norm,NW Ohio, detached well insulated garage. Concrete sealed after pour. Moisture condenses on inside windows and floor (not as much as yours). Salt from the cars could add to the problem. The main culprit is the warm moist outside air condensing on the cold slab. This happens to me occasionally. You may have to raise up the storage areas to keep things dry. Best of luck.
*Attached, insulated garage? Or detached, uninsulated? Sounds like the former, as my detached, uninsulated garage in a comparable climate as yours is rarely cooler in the spring than the outside, ambient temperature, just from solar radiation. If you don't wish to ventilate the garage, I'd live with the seasonal problem.
*Generally, as we all know, condensation is caused by a temperature differential - like the outside of a glass of ice water on a hot day. Another part of the problem could be that a vapor barrier was not applied below the slab, and that some of the moisture is migrating up through the slab. A way to test for this might be to somehow dry an area of the slab. Lay an aprox 4' x 4' piece of polyethylene plastic over the area. Pick a high area on the slab so as to try to prevent water from the surrounding area from running under the plastic. Then cover with some folded blankets, insulation, or some other insulative material and something heavy on top to keep the plastic pressed tightly to the concrete. A few days later, remove the insulation blanket and the plastic to see if there is water under the plastic.Please let us know what you figure out by posting to this thread.
*yup, I did the plastic test, and the result was: no moisture is coming up from below.The garage is a separate, uninsulated building. It is raised up from the surrounding area and is only used to store my good car (no rain or road salt being brought in by that!)So all the water is being condensed from the warm air.The other garages (I have 4, that's why I bought the place!) do not have this problem.As soon as it warms up enough I'll try one of those cement cleaners and see if the floor will absorb the water better (maybe there's some sealer on the floor).The other thing I guess I've got to do is add a door for me so that I don't always have to open the big door (and let in so much moist air every time).
*Warm moist air moving over a cold surface and dropping a load of water is a force of nature you will not alter. You will have to change something. You say the garage is raised. Do you have a lot of the slab exposed around the outside? I would suggest a couple inches of foam insulation around the outside of the slab followed by a bit of landscaping to raise a berm of earth over the sides of the slab. I would then insulate the garage, install a small heater and a ceiling fan. You might even cover the floor with indoor/outdoor carpeting for the insulation effect.
*As strange as it sounds, the carpet may be the best idea yet!Thank you, everyone.
*Carpeting in garage + hot catalytic converter in car = big garage fire. No more dampness and no more car. Don't do it!
*I'm going to assume that this garage has at least one recep. and a little open floor space. If so, how about a de-humidifier? It doesn't even have to run all the time. Look through greenhouse supply catalogs for various temperature and humidity-sensitive switching options. I believe this would be a less-expensive and comparable option to heating; just a different way of modifying the dewpoint at the slab surface.
*Yes, heat could be a problem. If your vehicle has high ground clearance it minimizes the problem but you could put down a metal sheet under the converter; maybe attach it to a sheet of plywood.I don't think a dehumidifier will help. This problem occurs too fast. Besides, normal household dehumidifiers freeze up at about 70 degrees and the problem here is that it is cold in the garage. You must either warm the floor or keep the floor separated from the warm, humid air.
*yup to both points.household humidifier shuts off below 70F and couldn't deal with this volume anyway.The best solution, as discussed on this webside elsewhere (humidity / venting) is, I think, isolation: keep the warm, moist air away from the cool surface. So, adding a pass-door for me to enter/exit the space with minimum air transfer and a carpet as pseudo barrier / insulation should help (the space is used for classic car storage in winter). Heating the space would cure the situation, but at high operating cost.But the huge ammount of water in this space, compared to the other garages I have, tells me that there could be some kind of sealer on the concrete. I'll let you know after I get a chance to use some cleaners on it...
*If you've got to spend to solve, how about this-Put a mask on and rip 2" x width of garage sleepers out of ground contact PT., re-treat sawn surfaces. Place on your choice of centers, rip high-density 2" foam to fit between, screw 3/4 or Your choice of T&G plywood running down length of garage with proper stagger, spacing etc. Now put down carpet or don't then park on it. Except for a people door that swings in... this might work. The only way you might be able to spend more is to buy that silly humidifier, pull out one of its frost plugs and install a block heater, one for a large KW ought to do the trick.