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Basement Waterproofing Solutions: Understanding Downspout Extensions

Jun 8, 2012 • By Matthew Stock.

Basement Waterproofing Solutions: Understanding Downspout Extensions

It’s raining again but that’s OK.  You’re warm and dry inside, knowing that everything’s OK outside as well.  You cleaned and repaired your gutters a few weeks ago and rain water is flowing as it should, into the gutter and down the downspout.


Or is it?  You read somewhere that one inch of rain produces 1500 gallons of water on an average roof and that’s what inspired you to make sure your gutters were in perfect condition. But, did you think about where those thousands of gallons of water are going once they leave the downspout?

Unfortunately, if you’re like most homeowners, all that water is being dumped right next to your foundation and, sooner or later, some of it is going to find its way into your basement.  Proper yard drainage may be the difference between a sound foundation and one that has leaking cracks in the walls and potential structural issues.  Installing the right downspout extensions is the key to proper management of those thousands of gallons of rainwater.

When it stops raining, take a walk around your neighborhood and look at the downspouts on your neighbors’ homes. Typically, you’ll see three ways of handling downspout discharge – one that guarantees a foundation problem, one that may save the foundation but looks awful and one that disposes of rain water properly without becoming an eyesore.

What’s the best basement waterproofing solution to managing downspout discharge?

No downspout extensions — Nothing good happening here.  Water is being deposited No Downspout Extensionsright next to the foundation, setting the stage for future structural problems or making existing ones worse. Soggy subsoil is one of the major causes of foundation cracks and cracks are a leading cause of water in your basement.

Long ExtensionsAbove-ground plastic extensions — Better than nothing but not much.  If these 3 - 4 foot hardware store extensions are properly installed and maintained and are long enough, they can divert water away from a foundation.  Too often, however, these extensions are knocked off the downspouts by kids, pets or landscapers, or fall off on their own, leading to water being dumped next to the foundation.

The extensions typically sold in hardware or big box stores are too short to help much but, if the homeowner is savvy enough to realize this and installs longer ones, his house resembles a giant octopus with its arms extending to the middle of the yard. Nice look, huh?

Downspouts that lead away from the house — This is almost always the preferred Underground Downspout Extensions choice.  When properly installed, an underground downspout extension is permanently attached to the downspout and it is guaranteed to carry the water far from the foundation.  Fitted with a debris filter, the underground extension ensures a free flow of rain water to one of several destinations.

Often, underground extensions will connect to storm sewers, although many municipalities now discourage this practice to prevent back-ups.  The preferred option is to send the water along the slope of the land to an open discharge point, but slopes are few in this part of the country.  The best option may be connecting to dry wells or bubbler pots that collect discharged rainwater and allow it to escape in moderate amounts.

The next time it rains, get an umbrella and go outside to see where all that water is going when it leaves your downspouts.   If your home looks like one of the first two situations above, you need some help to prevent foundation problems before they start. 

When it comes to managing water around your foundation, we at U.S. Waterproofing are the experts.  We’d much rather fix a problem in its early stages when it’s easier and more economical for the homeowner, which is why we’ve installed thousands of underground downspout extensions since our founding in 1957.  We’d be happy to offer free advice on fixing your downspout problem, so please ask.

Tags: yard drainage, downspout extension, downspout extensions

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