Wet basement, why it happens, how to solve
Many homes in our part of New Hampshire are built into hillsides that have ground water close to the surface, especially in the spring and after heavy rainstorms. Because they are on a slope, the dewatering system for these homes and businesses can simply use gravity to carry groundwater safely away. The system that is used to gather the water is often called a “french drain,” a footing drain, or a perimeter drain because it usually is installed around the perimeter of the footing of the foundation. Ideally such a drain carries the water down slope to “daylight.” Properly installed and maintained, such a system can be very effective at its job. However, many systems are poorly installed and even more are not at all maintained and often totally forgotten until water backs up into the basement or living space.
Since gravity basement drainage systems are seldom examined by home inspectors unless there is or has been a problem, and new homeowners have too many other things to fill their minds, foundation drains are too often overlooked. So how can a diligent home owner tell if the building has a drainage system or not? Sump pump systems are obvious, but gravity perimeter drains usually are not. One easy way to tell on newer homes is to look at a copy of the septic system plan that should be available and kept with important documents such as the deed. If the house is on a hillside and the septic system occupies a mound in the yard usually downhill from the house indicating that the area has a high water table, there should be a sketch on the plan showing a drain outlet at least 35 feet from the corner of the leach field., 75 feet for older systems.
For years I’ve helped home and business owners locate, troubleshoot and repair these drainage systems, sometimes with as little as a couple of scoops with a shovel to uncover the end of a forgotten drain outlet and other times with the major undertaking of excavating around the foundation to reinstall a proper drainage system. After having written several articles about basement drainage over the years I’ve put them all together in an on-line publication called KEEPING YOUR HOME’S FEET DRY. This document covers sump pumps and gravity perimeter drains in great detail, with photos and descriptions from personal experience. It is available free at www.RuralHomeTech.com /wet-basements/