Messages and Online Forum Q&A

Re: New Construction - Basement in High Water Table

From: info@builderswebsource.com
Category: Foundations and Basements
Remote Name: 209.47.98.184
Date: 02 Jun 2002
Time: 10:08 PM

Comments

You are rebuilding your home on Long Island and want to know whether adding a basement with a known 4-foot high water table is problematic. First, we commend you on following a engineering approach to this, which includes the test hole that you drilled. Basements do exist on Long Island, so it is possible to build one with proper civil and structural engineering. However, the water table on Long Island is gradually rising (see an interesting historical perspective on this at http://www.lihistory.com/1/hs108a.htm). Therefore, if the base of your foundation is below the water table, you are virtually guaranteed of an ongoing drainage situation. Given that your lot doesn't have any way to drain via gravity, you'll be forced to channel the water with a perimeter French drain into a sump, requiring some type of electromechanical means to keep you basement dry. The lower you go, the more water you'll intercept. Therefore, we strongly recommend against building your basement much deeper than about 3 feet (assuming the 4-foot water table level is based on the peak conditions).

Furthermore, you should hire a licensed civil engineer or geotechnical engineer to evaluate the results of your test bore and make specific recommendations to accommodate your drainage situation. In addition, assuming you decide to move forward with your basement, attention to detail is everything when it comes to preventing water migration under the floor or through the walls. Make sure you hire a contractor who really knows what he is doing, including the ability to follow the plans and recommendations set forth by the civil and geotechnical engineers. Additional information on Residential Drainage and Basement Waterproofing is available at: http://www.amazon.com/paypage/P3AXA5J8I1NRJ4. We recommend that anyone with a wet basement problem, or anyone planning to build a basement, should read this Technote first to better understand the considerations and techniques for keeping your basement dry year-round.

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