Mildew smell from crawlspace

geeshJune 13, 2011

I believe the strong mildew smell in my crawlspace is comming from the 40 yr old insulation overhead.The stink seeps up into the living spaces of the home. The old insulation is dark & looks in very bad condition. The home is on the Missouri/Arkansas border on a lake. HIGH humidity. I suspect that is where the smell is comming from.

1) How do I know for sure if thats my problem

2) I am think of having a contractor tear it all down & spray on insulation above the crawlspace. Is this expensive. 1800 sq foot single floor home ( avg 4 foot high crawlspace)

Thanks for your inputs.

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Mildew is the name traditionally given to fungus growth on fabrics and leather, etc. The growth of fungus requires the presence of moisture, the presence of food (wood), the lack of ventilation and the lack of sunlight.

Remove the moisture with a dehumidifier and/or introduce conditioned air to the crawl space. Ventilation from outside is not a good idea in a humid climate but it sometimes helps in the winter if the air is dry.

The insulation prevents air circulation so it might have to go. A good vapor retarder on the floor of the crawl space is critical for reducing the moisture in the space.

I don't know what you mean by "spray on insulation above the crawl space". In a humid climate it might be better to insulate the walls of the crawl space and condition the air in it.

    Bookmark   June 13, 2011 at 7:52AM
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I dont think conditioning the air would be practical. I do have a heavy mil plastic over the entire floor ( but it is not affixed to the foundation walls.. I can tell that the dirt is damp under the plastic. I thought the smell may be from under the plastic.. I dont know.. I have the vents all open, and a big exhaust fan blowing air out. I believe I am pulling new air IN from the vents & blowing old stinky wet air out.. The smell comming out will knock ya over- but does not seem to make any headway. After 2 solid days of letting it run- it does not seem to make a difference.
Looks like I will need to go down there & see where the fungus is growing & remove it. All the insulation above the crawlspace is dark- my assumption is it is all damp & mildewed- maybe not.. Pretty expensive venture if I am wrong.

    Bookmark   June 13, 2011 at 8:21PM
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If the fan is pulling in fresh air that is moist, the humidity in the space will not change enough to stop fungus growth. You need to close the intake air vents and draw conditioned air from inside the house into the space or seal the space and install a dehumidifier that drains to the outside or the sewer.

    Bookmark   June 14, 2011 at 7:40AM
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"seal the space and install a dehumidifier that drains to the outside" Thanks for the reply. This is something that I can do..I never checked the humidity in the crawlspace- but I should.. I will check the unit I currently have in our fulltime home & see if I can attach a drain hose. If so I just may try that out. What level of humidity should I set the dehumidifier for ? As dry as possible ?
Thanks again..

    Bookmark   June 14, 2011 at 2:47PM
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