Best crawl space drainage?


If I want a drainage system in my dirt crawl space, is french drain the only choice? I believe they clog up after a number of years, perhaps between 10 to 20 years.
I need a non clogging drainage system because I also want to install a vapor barrier that seals the ground as well as the foundation wall. If the drainage system clogs, I would have to rip the vapor barrier to repair it.
I'm located in washington state near seattle in case you have region specific recommendations.
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Drain systems installed properly for your soil dont clog, mine is near 100 yrs old and runs a river of water to the pit. Im sure the best built old homes in your area have systems that work, find out how they did it, maybe the city engineer or architect, they will help for free. I installed one a few years ago and used the sock over the tube and surounded the tube in about 18" of gravel, but that isnt how my old system was done and I have no idea what is really best, there is a way. But after it drains you need a pit and pump inside so it doesnt freeze.
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david wrote:

Is the water coming UP from the water table, or UNDER the foundation from the outside? Crawlspace is basically a real short basement, and same advice applies- stop water, if at all possible, OUTSIDE the walls, with proper grading, proper sealing, proper backfill, and an OUTSIDE drain tile at footer level, draining to daylight or a drywell. If you simply have a high water table, you may not be a good candidate for the type of sealing system you describe, unless you can figure out the underground water flows on your lot, and find some way to divert it upstream.
(This is the type of stuff a builder should look at before they build a house on the lot, but few do. Dig the hole, leave it a week, and see where it gets wet, etc.)
-- aem sends...
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Unless you have a high water table or something that causes the water to come up from below, your best bet is to steer as much water away from the foundation as possible.
Install a french drain around the outside perimeter of the foundation. I used 4" corrugated drain pipe with the slit perforations. Wrap the pipe with landscaping fabric, or install dedicated "socks" to keep the slits from clogging. I installed our drain in gravel, and covered it with a layer of gravel to improve drainage, wrapping everything with landscape fabric to prevent soil from working it's way into the gravel drainage layer.
Of course, the french drain should "drain" somewhere, whether that's off over a hill, or into a drywell away from the house where water can soak in slowly.
Once the drain is in, make sure your yard slopes away from the house so surface water isn't directed towards the foundation.
Also, install a good gutter system on your house, and run a separate drain line to direct the water away from the house. Do not tie the gutter drains into the french drains, or you might end up sending water towards the foundation instead of away.
If you have water inside the foundation walls, you'll probably have to install some kind of interior drain and a sump pump to remove the water that collects.
Anthony
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david wrote:

I can't imagine putting a french drain under the house. It is for *grey* water? Grey water drains not allowed there and don't want anyone to see it?
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