Crawlspace - sill plate is wet.


Old 12-11-18, 03:25 PM
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Crawlspace - sill plate is wet.

The sill plates are wet in December. This is for the Chicagoland area near the Lake.
I noticed that the Sill had sections that were wet during the summer and thought it might be some water leaking in from a couple of places where something enters the wall. Like the gas pip and A/C pipe. I caulked all around them thinking they had to be the culprits. My roof has an overhang and I don't believe water is coming down the walls.
Well, now that it's cold outside 20-30' weather and it hasn't rained in a week. I went into the crawlspace to shut off the water faucet for the backyard. While down there I noticed that the Sill is very wet along most sections.
This is really strange. There hasn't been any rain, so now I'm at a loss as to why the sill is so wet.
The next thing I was going to do was close the vents for winter.
Before doing that I checked the humidity monitor that I leave in the crawlspace. To my surprise it is showing 88% humidity.
I read a couple of posts about how the sill can become wet from moisture in the crawlspace.
The crawlspace is vented. I do have a dehumidifier in there that I used during the summer with closed vents to keep the humidity down to 55%.
I tried using a plastic moisture barrier on the dirt floor before but it did not stay in place. I did that when I first moved in and didn't know how much water builds up in the crawlspace during the rainy season in early spring. It caused the plastic to float and part of it flowed into the sump pump basin.
I was wondering if I should try the moisture barrier again but I'm afraid even with bricks trying to hold it down that it will get ripped up and be useless again in the spring when the water level rises again.
Any ideas?
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Old 12-17-18, 10:56 AM
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Pictures of the Sill

I took some pictures of the Sill. The sill is wet in most places. Along the wall where the crawl space vents are, those sill areas and the corners are completely wet. There are some sections on the two walls where there are no vents that have some dry areas but most are wet at least somewhat.

I don't know if it's the moisture trapped in the crawlspace that's causing this or maybe it's moisture leaving through the vents that's causing this or whether it's moisture coming from outside the building along the exterior walls that's causing this.

I pulled the insulation away from the wettest sections and there is water building up on the flooring overhead. I am guessing that maybe it's just wicking into the wood above from the sill but I am not sure. Should I remove this insulation from the gap nearest the sill plate to let it dry out? I'm going to install some vent fans in today to try to get some air circulation and dry it out somewhat. At least hopefully to get the humidity down from 80%.
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