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jimbo mail
Help with Crazy Crawl Space

Hi. We bought a 1939 home in tennessee last year, where it is pretty humid. The house has a recent (2006) master bedroom addition on the ground floor and a crawlspace/storage area underneath its floor. We don't use the crawl space at all. Over the weekend I opened the door to the crawlspace to store some items and found what appears to be yellow mold or slimy stuff in several places on the wood boards that cover a cement slab. Not sure why the wood boards are there (I assume previous owner put them down because the cement is rough and this provided cleaner storage space).
The crawlspace has a partial dirt floor and it is very humid.
Do I just wash off the mold (if that's what it is)? Rip up the wood planks and leave the cement slab? Do I need a more permanent solution to address the humidity level?
Any help or suggestions appreciated. I zipped some photos and can provide more if useful.

Timothy Miller
Re: Help with Crazy Crawl Space

hi consider putting plastic over the dirt floor to stop moisture from the soils. The mold on wood can kill with one part Clorox to to parts water in a spray bottle. I would remove the wood as it is a food source for the mold an you are not using it. I would consider spraying the wood framing of your home in this area with Borax this stuff easily strayed with a pump garden sprayer will keep fungus from working on your homes framing . Here is a source i have used to get it. http://doyourownpestcontrol.com/timbor.htm#directions

Re: Help with Crazy Crawl Space

All that wood will have to be removed. Unfortunately, according to the EPA there is no 100% safe and effective way to remove mold from wood and any other porous, absorbent and organic surfaces.

If you have fiberglass insulation between the floor joists, remove that as well. Wet fiberglass has no R-Value and has the potential to support mold growth.

I would suggest you call a crawl space repair expert to check the floor joists, subfloor and other wooden structures for dry rot, moisture level and structural damages.

I would also strongly suggest that you encapsulate your crawl space: a technique recommended as best practice for crawl spaces by many reputable independent and government organizations including Advanced Energy, Habitat for Humanity, Building Science Corp. and the U.S. Department of Energy.

Encapsulation consists in lining the whole crawl space with a sturdy (20mil) vapor barrier, sealing the space air tight, completely isolating it from the ground and outside air and including it in the internal envelope of the house.

The space should then be conditioned by using a crawl space conditioner or a crawl space dehumidifier.

This inexpensive and relatively simple process not only eliminates moisture and related problems in the crawl space. It also curbs energy losses and, according to many studies, makes homes an average of 18% more energy efficient.

I'd also like to recommend that you do not attempt to do it yourself, specially if you have combustion appliances running in the crawl space, as these need a consistent air supply. You don't want to de-pressurize your crawl space with these appliances in it.

Here's some more information on the science behind crawl space encapsulation:


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