condensation on shop floor

[cheap 40]

I figured I'd collect some 'Mud wisdom on this one........

Every time that it warms up a little, my shop floor sweats like crazy. My opinion is that the shop is insulated well enough that the slab stays cool, and of course, when the warmer humid air hits it, it sweats. I know that I could stop this by constantly heating the shop, but it is 27x60 and I don't want the proPAIN guy to get to know me that well.

I was out there this morning removing the front arms from the '97 for caster bushings, and it was like I washed the floor down with a garden hose first. By the time I was done, my legs were soaked from the floor.

Any other options out there besides heating it? Thanks.

Tony

[photogod]

Sounds like you might have a lot of moisture comming through the concrete. Maybe run a dehumidifier. Might be cheaper than heating the space.

[45Kevin]

Is the ground thawed out yet? It may that you had a lot of frost under the slab that is now melting. Digging a trench around the perimeter and adding a layer of styrofoam would solve this problem.

If this happens all year long just ignore this post.

[MoJ]

Has it done this in years past? Does it do it all spring/summer or just initially?

If it's condensation (the cool temp of the concrete causing the water vapor in the air to collect on the surface) then it sounds like you just need to work on improving the air flow.

If it's seepage (water coming through the concrete) it's either melting ice or an exterior drainage issue. I was in central/eastern IA this week and noticed the rivers out due to heavy rains. Is the ground around your shop sloped properly?

[Cattledog]

We have the same issue at work.... the problem is dew point and the temp of the concrete. You have two choices...

1 Heat the floor, This is our option currently it is the least expensive way out. If you are interested in this I will as my facilities engineer for the product's name.

2 Climate control... Air Conditioning, way to expensive for where I work. We change out 100% of the buildings air every 5 minutes.

Good luck.

[wfd175]

If there is gravel under the concrete, vapor barrier? make sure the gravel can drain. If you've backfilled up to the exterior of the footing with dirt, you may have, dependent on soil conditions, impeded the flow of water out from under the slab.

It may involve overexcavating the exterior a little bit and putting in a draintile. There are some sealers that you can put on the floor to help with the sweating.

[cheap 40]

Originally Posted by photogod

Sounds like you might have a lot of moisture comming through the concrete. Maybe run a dehumidifier. Might be cheaper than heating the space.

Maybe. In the middle of the summer we can get torrential rains and this doesn't happen though. I'd have to have a huge dehumidifier - 27x60x14 foot tall.

Originally Posted by 45Kevin

Is the ground thawed out yet?

Been thawed for about a month now.

Originally Posted by MoJ

Has it done this in years past? Does it do it all spring/summer or just initially?

If it's condensation (the cool temp of the concrete causing the water vapor in the air to collect on the surface) then it sounds like you just need to work on improving the air flow.

If it's seepage (water coming through the concrete) it's either melting ice or an exterior drainage issue. I was in central/eastern IA this week and noticed the rivers out due to heavy rains. Is the ground around your shop sloped properly?

This is only my second spring here, but it did the same thing last year and for the last two winters. When it happens, I try to open both front and rear doors to do just that (when the temp allows). I'd hate to do that when it's 15 degrees though.

Originally Posted by Cattledog

We have the same issue at work.... the problem is dew point and the temp of the concrete. You have two choices...

1 Heat the floor, This is our option currently it is the least expensive way out. If you are interested in this I will as my facilities engineer for the product's name.

2 Climate control... Air Conditioning, way to expensive for where I work. We change out 100% of the buildings air every 5 minutes.

Climate control is not a very good option for me. I have thought about heating the floor though.

Originally Posted by wfd175

If there is gravel under the concrete, vapor barrier? make sure the gravel can drain. If you've backfilled up to the exterior of the footing with dirt, you may have, dependent on soil conditions, impeded the flow of water out from under the slab.

There are some sealers that you can put on the floor to help with the sweating.

No idea on the construction, it was done long before I got here.

This seems to happen independent of rainfall. In the summer, if we get a cool night around 60, but then it warms up to 90+ with high humidity, it will sweat some. In the spring, like today, we had a low of about 60, and an afternoon high of 72 with mucho humidity due to a strong cold front that blew through this afternoon. We got at least an inch of rain this afternoon and three tornadoes touching down in the area. it is now about 40 and windy as hell. Fall seems to be pretty good, as we don't generally get a lot of humid weather then.

You can just see the side of the building in this thread - http://forum.ih8mud.com/80-series-te...y-day-off.html

This is a 60x127 machine shed with 14' sidewalls. 100 foot of it is dirt floor, with the last 27 being an enclosed shop. On the end with the shop is a 15 foot lean to on the outside that runs the entire length of the end. In front where the LX is parked is asphalt/concrete. It's like a parking lot!! It's on some of the highest ground on the lot, so I would think that most of the water would simply drain away through the tiles and runoff.

Good Lord, my fingers are tired. Sorry for being long winded....

Tony

[Toyo FJ40]

This use to happen in the section of my house thats on slab. The floor had a vinyl flooring over the concrete. The humid air would hit the cool floor and the vinyl would get wet enough to slip and break your ass on. We covered the vinyl floor with carpet and never had the problem again (carpet stays dry too) I think it was just a mater of keeping the air from coming into contact with the concrete. Maybe you could try some of that rubber fatigue matting or the shop plastic tiles that have the air space under them.


Kevin

[cheap 40]

Might not be a bad idea. Thanks.

Tony

[webelk6]

IMHO this odd spring we have been having just does not give a consistent temp for the 'crete. My garage floor does the same thing, and it is painted. Today it is 40 out with a mix of snow/rain. I think in a week or 2 you should be fine. FYI i am in WI, so we have very similar climates.

[freebie]

Hi cheap40
sounds like your floor does not have a vapour barrier below? or insulation? so if you heat the floor you may still find at random times there is condensation. One of the above posts mentioned ventilation. This requires a small fan continuously moving air from the shop to outside. This solution will be less costly than heating the floor or insulating the floor, but will work!
Whats happening is the moisture is weeping up through the concrete, and condensing. So if you can change the air quickly enough during the wet times? you will keep the problem in check.
The cooler outside air contains the correct amount of moisture for the local conditions, all you need to do is raise the air temperature in the shop slightly and the moisture is taken away by the exhaust fan?
Or better yet, if you want to spend a few dollars, have a heat recovery ventilation system installed, this system will recover some of the heat lost on the exhaust side?
Summary: if your floor is not insulated, or does not have a vapour barrier installed it will sweat, unless you keep the garage really warm! (this costs alot of money, because you are pumping heat into the frozen ground) The option is to ventilate a cooler garage!
BTW: you can't open up the doors and ventilate you will have to provide some heat and a minimal amount of ventilation for this to work!

Cheers and good luck

[cheap 40]

I might give that a shot. Any idea how much cfm I will need to move? The shop is 27x60x14 high.

Tony

[freebie]

Hi Tony

Half the volume of your shop divided by 60 gives you a 189 CFM fan, I would tend to undersize this a bit? try and get the fan near the floor and provide an opening as high as possible, on the opposite end of the building to try and pull some warm air off the ceiling. The problem with the smaller fan is it will take a long time for it to catch up or remove alot of condensation. If the fan is too big it will ventilate the shop quickly but your heating costs will soar. The trick is to let the fan run constantly before and during the times when the weather conditions produce condensation and leave it off the rest of the time.
I would try and find a smaller fan and do a temporary setup, it might take a few days to clear up the condensation. How much heat do you have for the shop and what type of system is it??
A large good quality bathroom fan runs around 150-200 cfm range, the other option is to find the smallest furnace blower you can and run it its lowest speed. You can get these at the junk dealers, scrap metal yards or from the local heating contractor. (used of course from a defective furnace)

Cheers