Moisture-proofing crawlspaces

Anyone here with experience making a crawlspace moisture-resistant (with plastic membranes or other means)?
Please read the question carefully before answering. Not looking for speculation or even helpful links to things I can find myself on the web. Looking for personal experience. (Funny anecdotes accepted as well.)
Reason for the question is a client with a damp crawlspace, dirt floor, and an overly-humid house. (Older house, vents installed, but no circulator, dehumidifier, etc.)
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"David Nebenzahl" wrote

Only a funny 'what not to do'. Mom was about to buy a house (we flipped houses for a living but it didnt have that name back in the 60's/70's). To attempt to seal this particular house, they'd tried to lay down plywood on the dirt then paint the heck out of it with water proofing paint.
Yup, you got it. Wet rotted termite heaven. We didnt even bother to look closer, just noted a huge termite infestation obvious to the eyes and walked off laughing.
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I covered the ground with 10' wide strips of heavy plastic sheeting, each side overlapped about 10" and taped with tape designed for plastic sheeting. Around the perimeter, I staked it down 16d nails run thru a plactic cap from roofing caps. I have found no signs of moisture in my crawl space. However I did get a few holes in it where mice got under it and chewed their way out. A few handfuls of Decon thrown under there once a year stopped that problem.
Red
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On 1/8/2009 10:10 AM Red spake thus:

Thanks. That's close to what I was thinking of doing.
Now for the next part: client would like to be able to walk on the dirt (uses crawlspace, which is nearly basement height, to store stuff in). How about throwing down a few sheets, say cheap OSB, over the plastic? Would that be stupid and attract termites? The idea is to protect the plastic membrane from being perforated.
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I think I'd instead be more inclined to throw down some pieces of concrete backer board or stepping stones. I doubt termites would like those.
Neither your nor my suggestions are really good solutions. The right thing to do is to pour some concrete.
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Steve Bell
New Life Home Improvement
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With a "crawlspace" that tall, how do you know the moisture is coming from the ground and not through the walls? (I'm assuming it's dug out and not multi-feet above the surface). I would not use OSB because of potential termite problems. I would either pour concrete or use PT plywood.
Red
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David Nebenzahl wrote:

and commercial kitchen floors, would be a better bet. Or even plastic 48" pallets, if you can find a cheap local source for used ones. If it is that tall, why not dig out part, and pour a slab? Aside from the insect bait/rotting factor, you don't want a second vapor barrier, or anything that could trap and hold grit against the plastic.
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"David Nebenzahl" wrote

Best bet there? You know that green 'grassish' outdoor carpet stuff? You can get remnants pretty cheap. I'd use that. Wont trap moisture in.
This assumes pouring a base isnt in the plans.
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I had a damp crawl space. Plastic sheeting and a fan solved the problem. Lay plastic sheeting on the ground. Overlap as necessary. A small hole here and there when crawling or putting things on it is not a problem. My crawl space was in the shape of an L, with the small end not having a vent. After the sheeting was laid down, the humidity was still too high. They make vent-shaped fans that automatically turn on and off with the humidity. That solved the problem.
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