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Sump Pit ...

Posted by Jay J on April 15th, 1999 08:54 AM
In reply to Crawlspace dampness by David Plourde on April 14th, 1999 07:38 PM [Go to top of thread]


(Very good post. Thanks for the details.)

There are two types of sump pits: pit and drum. The pit-type is a hole 1/2 to 1 yard deep dug in permeable soil at the lowest point in your crawlspace, lined with concrete blocks, bricks, or stones, and covered with a lid to keep out flies and mosquitoes and to prevent children from falling in (if access to it is easy). The bottom of the sump is covered with 50-l00mm of gravel or crushed rock. This is what I suggest you do. Preferably, you line the pit with filter fabric before you start building inside it. This will keep dirt out. (Don't use landscape fabric. You should be able to find the fabric at a gravel yard. Again, not landscape fabric.) The pit should be about 3' x 3'. If necessary, grade your crawlspace towards the pit. You only need a grade of about 1/4" per foot, just enough to channel the water to the pit.

The pump should have a battery-backup system since you may loose power during a heavy rain. It's worth it. Use a float pump, and make sure the water is diverted well-away from your foundation (outside). You can't 'dump' the water into the sewer system! I know you've read a bit about water in a crawlspace but it's not common in code to allow a below-grade crawlspace (if you have one) to be build where there's a high water tabel. Slabs are usually required where there is a high water table. Go outside and take a look around. If the terrain is such that water will 'run' right buy your house during a heavy rain, or collect, you've found a source for the excess water. Secondly, the most common source of this water is due to blocked gutters, plugged downspouts, leaky gutters/downspouts, and lack of downspout extensions. In the next heavy rain, put on your boots, grab an umbrella, and go outside and inspect your gutters and downspouts. Plus, see if you notice if water is 'running' onto your lot from your neighbors. Downspout extensions should channel water at least 3' from the foundation. The grading around your home should be at least 1/4" per foot for a minimum of 3' AWAY from your foundation. Sight-unseen, I'd dispell the high water table theory at first. Again, go out in the next downpour and look up, and look down! Oh, one last point ... if the lowest point of your crawlspace is up against your basement wall (if you have one), see if you can work it such that your pit and the grading can be done such that the pit is at or up against the crawlspace wall OPPOSITE the basement wall. If the pit is up against the basement wall, you may add a new set of problems!

My best to ya and hope this helps.

Jay J

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