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Question DetailsAsked on 1/23/2013

Is it better to waterproof a crawl space inside or outside?

My husband and I just bought a home that has some pooling water in certain spots in the crawlspace. There are three sump pumps in the crawl space right now. We knew there were some issues when we purchased the home such as previous water issues and future waterproofing.

We have had four companies come out to give us estimates and their suggestions. Two of them said outside waterproofing including an outside french drain needed to be done while the other two said a french drain inside the crawl space and encapsulation was the way to go.

My question is which of the two is the better longer lasting solution? We have mold and wooden joists that are starting to rot and we want to get this problem taken care of asap to avoid further mold and structural issues. We also have a very low crawl space...about two feet and it already has a cement floor.

Thank you


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Voted Best Answer

Trying the least costly first would perhaps try good dehumidifier with drain house into one of the sump pits, Consumer Reports as good infor on same and the old issues are at your local library.
If that solution is not enough would go with interior drain tile aka french drain with river rock around the elephant trunk black drain tile with perforations between the sumps.
Would be pretty unpleasant job breaking out the concrete floor but we used to call the workers grunts for a reason. Make sure they poly between crawl area and living area to control the dust and perhaps if you have whole house vac leave it running with hose in area being broken out.
Jim Casper Salesman & Owner of 2 Waterproofing Companies in the day


Answered 7 years ago by jccasper


Having spent years working in basement and crawlspace waterproofing, I would have to recommend the encapsulation method.
If there are already 3 pumps and still pooling water there clearly must be a grading issue under the house. Fix the grading problem and simply encapsuate. As long as everything is graded toward one of the three sump pumps there should no longer be any pooling. If graded propoerly there should be no need for an interior french drain system at all
A dimpled plastic such as DeltaMS can be used to line the crawlspace floor. This will help water flow laterally from its entrance point into the crawlspace over to the sump pump. Encapsulate the crawlspace with at least a 10 mil plastic and install a dehumidifier that drains directly into the sump pump. Be sure your dehumidifier is large enough to maintain a relative humidity of 55% or less in the area. This will control the mold growth.
An exterior system may stop the pooling water but it will not likely drop the relative humidity levels low enough to stop mold growth inside the crawlspace. Also, it would be very costly to run a dehumidifier in a dirt crawlspace without a vapor barrier because as the air is dried more moisture is drawn up out of the exposed ground. If the existing mold is remediated but high humidity is still present, it is only a matter of time before new mold will grow again.

Source: http://www.EmpireBasementWaterproofin...

Answered 7 years ago by Dludwig123

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