Humidity in Crawlspace - Help Needed

[Sean]

Hi all, I'm a bit inexperienced in home knowledge so am hoping for some help from people who have had this problem.

We bought a 4 level split, with a cement crawlspace under the family room. It's sealed except for a little wooden door which is always closed. It's very musty smelling and the hygrometer I put in there says the humidity level is 92%. The rest of the basement is about 70% without a dehumidifier running.

I have a few questions.

(1) If I put a dehumidifier right in the crawlspace, will that help lower the humidity in the rest of the basement, in addition to lowering it in the actual crawlspace?

(2) Is there another way to deal with the crawlspace humidity other than with a dehumidifier?

(3) Is there a good way to get rid of the musty smell in there?

Thanks for any tips!

[SteveF]

I think the dehumidifier is like mopping the floor instead of fixing the leak. You need to find out how the moisture is getting into the crawlspace. If the floor of the crawlspace is concrete (cement is one of several parts that make up concrete) then the water is either getting in through the joints between the floor and walls or else directly through the walls since concrete is porous. If the floor is not concrete then you need to get some heavy plastic and tape and seal the floor.

First thing I would do is to seal up all the joints with caulk and paint all the walls and floor with something like DryLok. Then you can use the dehumidifier to control the amount of moisture in the air. Once the humidity is down the musty smell should go away unless you have obvious mold growth on the wood.

Here's a web site that will help.

Steve.

[Joseph Meehan]

Yes, but it is likely to lower the humidity in the rest of the basement only a little

Same answer to both 2&3: First, if the crawlspace does not already have a vapor barrier in place, then add heavy plastic from the sill at that top of the walls all the way across the floor to the sill on the other side. Overlap and tape seams. Next, ventilate. You need an air flow in and out of there. Either heated open to the existing basement, or un-heated with the floor above insulated and vented to the outside. Last make sure there is nothing outside contributing to the problem. All gutters in good shape and all water from the roof and hard surfaces like drives and patios is directed away from your home and all dirt is graded away from your home for at least 10 feet.

After that then you may consider dehumidifying equipment. That 70% humidity may not be bad, especially if the tool you are using to measure it is reading a little high. a 10% or greater error is not at all unusual and

60% humidity is considered fine for most situations.

[Sean]

Thanks for the tips guys.

[abi]

Hello, there is usually another problem associated with your problem if the sealing is the problem, which it probably is, and you may not have lived in the home long enough to know a winter, but it's likely the floor and the family room will be hard to keep warm.

Since it doesn't seem like a broken or leaky water pipe, or anything like that, then closed cell foam would be more likely to solve ALL the problems. Drylok is good for sealing the water out and plastic is good for keeping ground moisture out of the space, etc., but it doesn't insulate at all. If I were going to do something there, in the cramped crawlspace, I'd only want to do it once.

A Froth Pak or Tiger Foam Kit would take care of all the problems. Seal, insulate and caulk in one application, basically. These kits are easy to use, just make sure you get closed cell and not open cell foam. I just have a feeling that is a hard room to heat and cool. I have a similar floorplan and had a problem with moisture, but mine turned out to be the outside faucet leaking in the cinderblock. (just something I didn't consider and was surprised at when I discovered it because I couldn't see the pipe in the crawlspace as it was behind a cross board)

I hope this helps somewhat.

abi

Sean wrote: