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Discussion Starter · #1 · (Edited)
We are renovating a room in our basement and noticed the carpet had some staining in the corner of our room. Upon further review we noticed there was a buildup of condensation between our rigid foam and vapor barrier that was running down to the bottom plate and under the carpet. I live in North Iowa and we noticed it in the spring when our basement was cool and outside temps were warming up. The exterior of this area is ground and block covered. No issues since.

The main area is going to be under stairs and we would like to carpet it. My thoughts were to either remove the rigid insulation and put batt insulation while keeping the plastic vapor barrier. OR remove plastic vapor barrier only and replace drywall. However i can only do that in the small space under the stairs.

Any thoughts on if this will work or whats causing this? Thanks

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Assuming you have eliminated all possibility of water from outside, then you may be dealing with condensation. But your pictures seem to be very localized and condensation tends to affect an entire wall. So I'm confused.

One issue may be the vapor barrier preventing any drying to the inside. Even rigid foam board allows a little. If warm humid air can reach that cold wall there will be condensation. With no direction to dry it will accumulate which may be what you are seeing.

Others will comment. Below is some reading.

BSD-103: Understanding Basements

Bud
 

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Discussion Starter · #3 ·
Assuming you have eliminated all possibility of water from outside, then you may be dealing with condensation. But your pictures seem to be very localized and condensation tends to affect an entire wall. So I'm confused.

One issue may be the vapor barrier preventing any drying to the inside. Even rigid foam board allows a little. If warm humid air can reach that cold wall there will be condensation. With no direction to dry it will accumulate which may be what you are seeing.

Others will comment. Below is some reading.

BSD-103: Understanding Basements

Bud
We have noticed it in these two areas. The one on the right being the largest and showing floor staining. The left being a smaller dampening of the floor only a few inches out. Makes me believe its condensation but not sure if its due to have two vapor barriers with the plastic and rigid foam.
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Please give some more detail on the type of foam and the thickness. Is it continuous ?

And please confirm -- the condensation is on the concrete-wall-side of the vapor barrier ?

What year was your house built ?

Do you have drain tile and sump pump and do you know if it is working properly? I wonder if the source of the moisture is the footing/wall interface sitting in a very wet environment
 

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Please give some more detail on the type of foam and the thickness. Is it continuous ?

And please confirm -- the condensation is on the concrete-wall-side of the vapor barrier ?

What year was your house built ?

Do you have drain tile and sump pump and do you know if it is working properly? I wonder if the source of the moisture is the footing/wall interface sitting in a very wet environment
1. Built 1968 but I believe basement insulation was added around 2010
2. Concrete Block > 2x4 flat side w/ rigid insulation>condensation>vapor barrier>Drywall
3. Foam - Expanded polystyrene- 1.5" inbetween flat laid 2x4 basement level only, stops at floor joists
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4. No sump pump > previous owner said they have never had surface water issues. I only noticed this issue when we saw a little discoloration in the carpet and once removed noticed moisture on carpet tac strips and carpet pad.

We have lived there two years and the previous owner had significant landscaping done about 10 years ago. Downspouts are in the area and work appropriately. I dont believe there is any drain tile. We live on an elevated area but on a marsh property. Since it used to be a garage opening there is no foundation in the sections between the block wall and that is right on grade. However the moisture is not present in those areas and primarily areas with block (which makes me believe its condensation).

Hope this helps.
 

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Is that downspout far enough from the house?
Just a consideration, looking at the slope in the last pic, is is possible that the water is coming back to that corner of the house?

Edit... I'm not fond of the downspout and slope on the other side as well
 

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Discussion Starter · #7 ·
Is that downspout far enough from the house?
Just a consideration, looking at the slope in the last pic, is is possible that the water is coming back to that corner of the house?
comes our 5-6 feet on a immediate slope. Small area does taper back in the corner of the house and retaining wall. Its north facing with 2' overhangs and decent tree coverage.
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Normally, the warm, moist air is on the inside of the house, and then it might hit a cold wall and condense. That's why one puts the vapor barrier where it is. But I don't think that is what is happening at your place.

I think the source of the moisture is from the outside.
Could be just transferring through the concrete. Or could be a small leak. That looks like quite a bit of moisture.
What temperature do you keep your basement at ?
 

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I would open up this part of the wall, by removing the vapor barrier and insulation. There may be mold between the blocks and insulation, that must be removed. You should be able to get a better idea how bad the moisture problem is, by digging a little deeper also.
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I am in KS so likely similar climate as you are. I have owned four or five homes with basements with concrete walls and have never had even a hint of condensation problem. I have never had a vapor barrier near the concrete, either. In my area the basement construction is all pretty similar - tar-like goop on the exterior of the basement concrete wall before backfill keeps water from coming horizontally through the wall. Drain tile and sump with pump take what makes its way to the bottom of the outside of the wall to the outside as needed. I have in my current home slim studs with sheetrock to form the interior walls (against the exterior concrete) but there is some room for air to circulate behind the sheetrock to keep everything dry. I am no pro about condensation but that looks like too much in a too-small area to be simple condensation.
 

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If, if, if,
If the wood is touching concrete it will be cold.
If house air could get in the space where the bottom of the VP is not sealed or under the wood where it is not sealed,
it could be condensation.
If the high foundation comes around the corner and drops down to a level like a slab on grade you could have a leak between the wood and the concrete where they meet.
If the perimeter drain is no longer working and you could have water coming up from below.
If they did not damp proof, (black goop) right to where the concrete meets the wood you could have a leak thru the concrete.
Opening the wall and looking for evidences behind the insulation will give you a better idea of what is happening.
 

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Odds is 90% leakage though probably 100% - highly unlikely you have enough air leakage hitting those spots & due to the ground buildup in that area the temps are not as low for condensation to occur.
FYI you should not have plastic there & that foam - if it is what I think it is worthless. Looks like you are opening up not only higher in that area but are going to have to go around the perimeter until you find fully dry which includes that whole corner
 

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Discussion Starter · #16 ·
Thanks for the comments. It is most certainly a water leak. Opened up the wall and sill plate was rotted. Then i took off the downspout in the corner because i had to remove some siding. We got a heavy rain and water all over the basement floor coming in from where the block meets the wood framing. Never been like that before. So well be doing some grading, making sure downspouts are connected, and looking at other options for sealing that area from the outside.
 

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If you can find the spot where it is leaking, best is to fix the waterproofing on the outside.
Correcting slopes and downspouts is a good thing but if you don't go after the waterproofing it is just a band aid waiting for the next time.
 

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Unfortunately, you have cmu block walls.
With poured concrete walls, cracks are more commonly vertical, all the way from top to bottom of wall. Easier to find the problem, easier to fix the problem.
With block walls, you have countless potential entry points.

You might want to call a pro. Google "wet basement name-of-my-town". You won't like the $ numbers he gives you.
 
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