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Moisture, Mold and damp ground in crawlspace

bbranch's Avatar

Join Date: Jan 2009
Posts: 1

01-13-09, 12:09 PM   #1 (permalink)  
Moisture, Mold and damp ground in crawlspace

Ok little background, located in Northcentral Oklahoma. House is 3 yrs old, stemwall is 24" tall, crawlspace entry is in garage, ground was cut out so I didn't have to put stemwall and footing on fresh soil. House is on side of hill and the cut was back into the hill. Make sense?? Dirt was piled up to the top of the stem wall sloping away on 3 sides and not piled up to top on one side. Since house was built have had a problem in the spring with water under one end of the house w/out the dirt built up to top of stemwall. Pumped it out. Over time I have tried to decide what i was gonna do as a fix. I got 2 humidistatic controled vents w/electric fans. Thought this may be a good start.Got under house to run electric and found that it was damp and mildewy and moldy on this one end of the house. Looks like all the inside of stemwall is wet to the touch and cans see some condensate on pipes. Also the tips of some of the dirt under the home is white. Is this mold also? I plan on putting vents on the other end of the house so during summer months can get a good air exchange working. After reading alot and not finding the answer I think I need, I'll just ask.

Should I get it dry before I start trying to get rid of mold?
If so how is the quickest, most efficient way to dry? (Winter)
Will vents on other end of house be suffecient after dry?
What is best way to get rid of mold? Bleach 50/50
Do I need to just spray or brush after/before spraying?
Know of any professionals if Ok/Ks?

Last edited by bbranch; 01-13-09 at 12:28 PM.
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CyFree's Avatar

Join Date: May 2008
Posts: 124

01-13-09, 03:12 PM   #2 (permalink)  
I think I have some information that can help.

The best way to dry out a crawl space, is not to add vents, but to actually close all the existing vents, then encapsulate, seal and condition the space

It may sound like non-sense, after all, when you want to dry anything you just let it air out right? The problem is that things work differently in the crawl space. The air doesn't move around as it would above grade.

In addition, the temperature in the crawl space is always different from the temperature outside and on the above floor. Those differences in temperature cause any moisture present in the air, to condensate all over the surfaces in the crawl space, allowing mold to grow.

In a humid region or in regions where you have high levels of humidity during any given season, crawl space vents can make things much much worse. The air that you are allowing in in the hopes that it will dry the place, is actually bringing in more moisture.

There are ton of scientific studies conducted by reputable organizations such as Advanced Energy and Habitat for Humanity, proving that crawl space vents don't work, and attesting to the benefits of conditioned and sealed crawl spaces.

Here are some sites with information on how to properly treat a crawl space I urge you to take a look at:


As for the way to remove mold.
1- If you dry the crawl space and keep the moisture levels under 50%, the mold will dry out and no longer pose a problem.
2 - If you keep the moisture levels high, the mold will keep coming back and trying to clean it up while the crawl space is still damp, might only cause it to release more spores in the air and spread all over, including the floors above.

Hope it helps.

twelvepole's Avatar

Join Date: Aug 2000
Posts: 15,834

01-13-09, 03:38 PM   #3 (permalink)  
In addition, you need to address the drainage issues. Gutters and downspouts clear and carrying water away from structure. Downspouts are best attached to drains that carry water to drainage ditch, dryw wells, or other. Just don't drain onto neighbor's property.

Soil should slope away from the structure so that runoff is directed away. If there is a slope behind or beside the structure, then place drains at the base of the slope to catch the water before the runoff reaches the structure.

You mention that the problem is in the area of the stem wall where dirt was not done as in the other areas of the stem wall. Perhaps creating the slope as on the other areas would help alleviate the problem. Do you have a vapor retarder overlapped and taped and run up sides of walls in your crawl space?

For stem wall construction info:

Stem Wall Foundations

Photo Credit: Raised Floor Living

"Moisture control of the crawlspace created by the stem wall foundation is an important issue." Footings and Foundations | Raised Floor Living | Southern Pine Council™ | 1-504-443-4464

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