Condensation issue

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RustyRatRod

RustyRatRod

I was born on a Monday. Not last Monday.
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Some of you may remember me having an issue with the concrete floor of my shop experiencing condensation. Something I've noticed since I've been spending more time out there. Only one side mostly sweats. The other side remains pretty dry. What are somethings I might could do to combat this? Would a concrete sealer work? Maybe an exhaust fan installed at the top of a gable end? I am tired of this and ready to do something about it.
 
RRR I noticed during the summer with my garage floor if I leave the doors open the whole floor will sweat. If I put a fan blowing across it, wherever the fan is blowing will dry but all around it is still wet.
I think the only cure is to close it up and turn on a dehumidifier.

I think the fix is to put insulation down on the ground and pour the concrete on the top of it the next time. Or a layer of plastic. I don't know the experts to tell us the fix.
 
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Any slab poured on the ground should have a vapor barrier under it before the concrete is poured.

If insulating too, put it on top of the plastic barrier.

Concrete is porous so ground moisture can travel up through it if their is no vapor barrier in place.

Trying to deal with it afterwards can be a pain.
 
Is it coming from below, or condensing on the surface? I have that occasionally if one of my doors isn't completely closed. Warm moist air flows in over the cold concrete and condensates on the floor. Curious if it does it all the time, or just on days that were cold at night and warm up considerably during the day.

What condition are your door seals in? I have one of my three doors that has a bad bottom seal (no seal at the edges) and I get condensation in the areas around it at times if the conditions are right.

Just a thought.....
 
Rob I have the same issue. I put up a ceiling fan helps out a lot.
 
Is the slab lower, below grade at this wet side? If so the moisture could be coming through exterior wall.
Hot goes to cold so slightly warmer moist air from outside would condensate to cold concrete. The dehumidifier is probably the best solution for year round control no matter where the moisture comes from. They move air mostly right where they are placed so If not placing it right in the center of the area ( like mine in the basement ), a ceiling fan will help circulate, improve performance.
 
Does it happen year round or more in a particular season?
 
had the same problem every time the door was opened the floor would start to sweat but only in front of door the rest of floor stayed dry so I had to keep the door closed and a high speed fan on until dry then turned fan on low speed .I'm building a new garage now and it will get Styrofoam under the slab !
 
I will second the ceiling fan recommendation. we put a cheapo ceiling fan in our garages after we figured out it. just leave them on low all the time.
much cheaper to run than the dehumidifier Dad use to run.
 
Ayup. I've seen this plenty of times. I worked in trucking for 40+ years, mostly based in the PNW. The weather up here is such that when it's cold in the winter, often the concrete dock would sweat, and that was on a slab sitting 4' above grade to load/unload the trucks. I had the same issue in my shop (SW Washington). I fixed it by putting two cheap-o box fans in the shop on a timer. I had the fans at opposite sides of the shop, facing the same way to make a "swirl" pattern of moving air. To the best of my knowledge, sealing the floor won't help. All our truck docks were sealed and still looked like swimming pools at times. I ran the box fans for about two hours a day, at the warmest time of day (1400-1600). I never had an issue after that. Also, insulating my shop helped a LOT with moisture inside.
 
RRR, I live southwest of Atlanta and with all this moisture we’re getting my garage floor is like it gets morning dew on it. I sealed mine a few months back and it still does it when we have that high humidity. Moisture is on top of the sealer. I think fans is probably the best fix. My issue is the mildew smell that comes with it. I hate it.
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Get the concrete up above 65 degrees and likely the problem will stop.
The foil backed bubble stuff is being used under concrete up here. Also 2 feet of styrofoam sm around outside of building,buried 4 inches deep. Moves frost line away from slab.
 
I will say that the door on the side that sweats badly does not close tightly to the floor. I'll fix that and see if there's a difference. Then I'm going to get a gable fan and install it. When the weather warms up, I'll seal it. Dammit all. Thanks yall. Yall always give me some good ideas.
 
A little extreme up here, buddy doesent heat his garage much, in spring puddles form in the low spots on the floor,until weather dries up and weather gets real warm.
 
Exhaust fan for sure on the cheap. With all the rain we have been getting how is the drainage around the shop? All on that side?

I am installing a Mini-Split in the garage this weekend to help with heat/air and condensation and expect it to help with the little moister I get now.
 
I can remember when you posted this problem before. How about using a temperature gun and measure the surface temperature of both areas in about 4 spots, each side.
 
g413 said:
I can remember when you posted this problem before. How about using a temperature gun and measure the surface temperature of both areas in about 4 spots, each side.
Click to expand...

That's a good idea. I hadn't thought of that.
 
RustyRatRod said:
That's a good idea. I hadn't thought of that.
Click to expand...

Just an FYI, Home depot has a basic clear epoxy garage floor coat for about 25 bucks a kit and has anti slip additive with it if you wanted to use it.
Don't know how big your garage is, but I would expect you would need a few of the kits to do a reasonable size garage.

I used it on our shower walls.:D
You should see some of the stuff people are doing with that epoxy.

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That's pretty cool stuff. The shop is 24 x 28.
 
It’s most likely condensation. When the surface temperature is lower than the dew point, water vapor in the air will condense on the surface. Therefore this will happen on high humidity days when the slab temperature is cooler than the dew point. This is tough to fix without lowering the humidity in the space or raising the temperature of the slab or air. Moving air over the slab will help by causing the condensation to evaporate.
 
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Oh yeah, that cleared it right on up. lol

I found a lot of the source this morning while it was POURIN down rain.....some more. It's actually leaking in around the bottom frame of the building against the floor. I still have some condensation problem, though. Going to get all this taken care of when it warms back up because I know nothing I put down right now will stay there.
 
same issue I went to Home Cheapo and bought 2 , $20.00 , 20" floor fans . Kept themon 24/7 on the lowest setting until I found out how much air is needed . On heavy rains I turn up the fan speed . the person that built my garage SUCKS
 
I have a small garage,when i first insulated and started heating it there was a moisture problem. De-humidifier sucked gallons and gallons of water out of the building.
Good thing, i moved my metal lathe in there.
Have to re-polish the anvils on my english wheel,but will never be an issue again.
 
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