Wet Crawl Space

I’m buying a 30 year old home and of course the crawl space has problems. The sump pump is defective and a large area of the surrounding gravel is wet. The gravel is several inches thick over a barrier which is good, but what is the best way to dry this space out when the gravel is this thick? Fortunately no mold, but you can smell the yucky dampness in the home. The crawl space is not vented.

One idea I found on the web is to place a humidifier in the center of the crawl and have two fans point towards the dehumidifier. Another suggestion was to have a heat vent warm the crawl, but it’s still summer.

Suggestions appreciated. :smiley:

Sure glad you corrected yourself :stuck_out_tongue:

Dehumidifier would be my suggestion also, but may take a while to get the job done. How large an area is wet? Just around the sump, or the entire crawl?


It’s wettest near the crud pump and spreads out about 10-15 feet. The crawl is about 500 square feet. I’m wondering if poured concrete would be a good investment.

You’re pi$$in in the wind until you fix the lack of ventilation. Did you check the floor structure for moisture content and rot?

2 foundation vents, opposite sides of the crawl.

1 humidistat controlled van, something like this: http://www.ddchem.com/Crawlspace-fan.htm

Works like a charm.

Dig a sump hole. Drain and pump it out.

Structure is fine. I don’t get the ventilation thing. It’s better that they’re *not *vented.

It does have a sump pump but that needs to be replaced. I’m not sure there is enough moisture in the crawl space gravel to drain and discharge. So I’m looking for ways to dry it instead. I may start with a dehumidifier, but what do you think about adding a heat source to the crawl?

Assuming it’s not a conditioned crawl space, it does not meet code if it doesn’t have ventilation. I’ve seen houses only about 10 years old with the floor system largely rotted out due to owners keeping their vents shut year round.

You’ve got wet soil and when it dries, the moisture goes into the air above it and it has nowhere to go after that except to get soaked up by the wood.

These are cool. But how does it help if it’s pulling in humid air?

Replace the sump and see what happens.

After that some forced ventilation is in order to dry things up.

You may need to treat the standing water in the gravel with a biocide before draining to kill off and possible mold or other organics.


Tell us a little about the property. Any slope? bottom of a hill? just water table?

I had a crawl space that could get white caps in the water when the wind blew through the vents. We put a linear french drain around two sides of the home and it has been dry since then, even during our 2 recent 100 year storms. Keep the water out, don’t wait for it to get there and then act.

I sent you a P.M. with contact info.


The slope is adequate but could be better. I think a new sump pump and a good dehumidifier will solve the problem. The gravel was wet but there were no signs of accumulated water.

That’s what I would do too, Erol, with the info you provided.

Joe’s SC location is different than up here and would present more humidity problems.

I like that method especially for our winters. I’ve done it many times with great success.

I insulated the interior of the perimeter foundation but not the floor joists. That heat supplied to the crawl space rises and feels good on the tootsies. :smiley:

No way one can tell if the vapor retarder is good, through several inches of gravel. One certaily cannot tell whether all joints are lapped 6 inches and taped, and whether the vapor retarder is turned up and taped to all walls and all penetrations such as posts and pipes.

Crawl spaces do not CREATE moisture. It’s coming in from somewhere, and in the absence of vents, it doesn’t take much incoming moisture for it to collect and cause the problems described. A properly dampproofed and ventilated crawl space witha correctly-installed vapor retarder should be bone dry in any climate. If it isn’t, one needs to find the source of the moisture and remedy that. Energy-consuming mechanical devices should not be required at all.


I think Erol is assuming that the crawl is wet due to the defective sump pump, as the moisture blooms around the sump pit.

I stick… with replace the pump, get the dehumidifier cranked up, and take it from there.


Agreed. We were just discussing whether a poured concrete floor (and a new sump pump) :wink: would be a worth while investment for the home and our health.

I have personally used this product,
Give me a call and I can answer your questions.

Erol, sounds like you have a plentum crawl space. Would take Andrews advice. Here in the south, I haven’t seen one of these that wasn’t a train wreck.

Encap it then condition.