Crawl space moisture

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Like yourself, I have had a similar problem. We are nearly on the crest of a ridge, but water tends to drain from front to back and cause moisture to accumulate in the crawl space. The problem is made worse by poorly permeable and rocky soils. A small amount of seasonal moisture in crawl spaces is hard to get away from, but standing water should be drained.

It is hard work but an interior drain system consisting of shallow ditches along the perimeter walls and as needed to drain water to the lowest point where a 4" gravity drain can be drilled through the foundation wall above the footer would probably solve your standing water issue and virtually eliminate surface moisture. If you want to get really elaborate, turn the perimeter ditches into french drains by inserting perforated pipe and covering with gravel. I had to use short-handled tools (pick and shovel) to get the drainage installed. Take your time and let the natural slope work to your advantage so there will be minimal digging. Don't get fancy, its just a crawl space.

Other hints: Ensure you have adequate crawl space ventilation. You could cover the space with plastic and fine gravel, but I tend to see that as more aesthetic than practical. Deal with the moisture in this fashion and it won't matter whether the source is groundwater or seeping surface water.