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Hi all, My workshop building is built into a hill on two sides. I have applied foam board to my block walls in my shop and then studded out the walls so I can apply fiberglass batts in the cavities. I went out today and noticed condensation on the foam. The foam has been installed for about a month now and I have not noticed this up to this point. It has been extremely wet out with all the rain we have had lately so I am wondering if this is the reason for the condensation? Also the outside temp has been the same for a while now. There were some cardboard boxes in my shop that also seemed damp? I am hoping once I get the fiberglass insulation in there the air will not get to the foam as much so it will not condensate. Any thoughts on this? Thanks in advanced.
 

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I doubt the foam board surface you can see is the only condensation point but also between the foam and concrete block surface.Take a temperature reading of the concrete blocks where the condensation is occurring along with the room air temperature and the allowable moisture in the air can be calculated for that temperature. As seasons change and the blocks become warmer or colder a different number assigned to the air moisture and room temperature allowed will be needed.
 

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ok, you are getting way too technical for me..lol. I have foam on the block as a moisture barrier and there is very high humidity right now. In fact my wife said the floors at the hospital was puddling with water because of the unusual high moisture right now. Her are some pics of what I have.
 

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There isn't anything very technical about it. I'm sure you've witnessed condensation on your cold drink glass. That's the same scenario where the cold air at the surface is unable to hold the amount of moisture present in the air at that location.

If you've ever seen an industrial rubber backed throw rug just inside a shop door with a concrete floor that has water under after a cool night you've witnessed the same thing. We would think that possibly the rubber back would keep the moist air, that occurs on some nights and early mornings, and condenses underneath would be sealed from the cold condensing concrete surface. It takes a way better seal than that and so it happens.
 

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ok, you are getting way too technical for me..lol. I have foam on the block as a moisture barrier and there is very high humidity right now. In fact my wife said the floors at the hospital was puddling with water because of the unusual high moisture right now. Her are some pics of what I have.
It's looking as if your wife knows more about what causes wet floors than the average person and more than some so called expert web sites. Good for her.
 

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I am no expert on the subject but I do know that the foam board is not a complete vapor barrier but slows the moisture migration down considerably. I think the problem is you have two different air temps/ humidities meeting. I think that once you install the fiberglass bats (or whatever insulation type you are using), drywall and a good latex paint
(latex paint is a good vapor barrier itself) it will slow down the air movement enough to prevent the condensation.

It's hard to evaluate parts of a system but impossible to evaluate them when they are together.
 
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