Gutter Helmet Blog

The Downspout Extender, Part 1: Protect Your Home from the Threat of Basement Flooding

white hinged downspout extensionWould you be surprised that one of the most effective ways to prevent basement flooding is with a simple piece of guttering known as a downspout extender? For many homes, this extension of the gutter system is a miracle fix for chronically damp basements and crawl spaces, or musty smells in these areas. Just by moving water drainage farther from the foundation, you too could spare yourself the cost of a waterproofing system or other expensive solutions.

To determine how far you should extend your gutters, consider the type of soil and the slope of the lot around your home. If you have loose, sandy soil where the builders filled in after construction was complete and this surface slopes toward the house, water will flow easily through the soil and pool around the foundation. This could even cause the structure to settle unevenly.

How Far to Extend the Downspout

If you notice that rain is not flowing away from the foundation during a heavy rain, it’s time to take matters into your own hands. Attach a rigid or flexible downspout extension, available at home improvement stores, to the end of the gutter downspout. Where there are basement walls, the National Association of Waterproofing and Structural Repair Contractors recommends that the water drain a distance of at least three feet and preferably six feet from basement walls. On sloped, clay-rich soil, downspouts should extend at least three feet from the foundation. On flat land, the Association recommends 10 feet unless the soil is very sandy, in which case the extender may need to be much longer.

If your downspout already extends a sufficient length from the house, be sure there is a plastic or concrete splash block underneath prevent water from eroding a hole in the soil next to the house. A splash block also directs water farther from the foundation.

Stay tuned for our next blog about improving the curb appeal of downspout extenders. For more information about gutters, visit our Rain Gutter Basics page.