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Divert Rain Water Away from Your Foundation with Underground Downspout Extensions

Apr 29, 2015 • By Matthew Stock.

Underground Downspout Extension

Basements can seep water through a number of openings – non-structural cracks in the wall, deteriorated mortar joints, cracks in the floor or the cove joint seepage between wall and floor. 

The damage can be averted and, in many cases, seepage prevented by diverting rain water away from the home’s foundation.  Many homeowners think that just by cleaning and maintaining their gutters that they have done all they can to accomplish this but they often ignore the end points of the gutter system – the downspouts.

Consider this – a one-inch rainfall dumps 600 gallons of water on each 1,000 square feet of roof and that’s more than 1,000 gallons on the typical home in the U.S.  A clean and properly pitched gutter system will collect all that water and prevent it from spilling over the edge of the roof and saturating the soil around the foundation.

However, if the downspouts merely terminate a few inches above the ground, or dump water on a small splash block, all that water collected by the gutters ends up next to the foundation anyway and in concentrated amounts in several spots.  Next stop?  The basement.

Underground Downspout Extensions Divert Water Away from the Foundation

The soil that surrounds a home’s foundation is particularly vulnerable to over-saturation because of the long-lasting effects of the excavation that was done when the foundation was built.  The excavator dug what was essentially a bowl in the ground and the foundation was built in the middle of it.  When the foundation was finished, the edges of the bowl were backfilled and, despite the contractor’s best efforts to compact the soil, it remains more porous than the undisturbed soil around it.

So, when excessive water lands in that “zone of failure” (approximately ten feet wide) it is likely to have a deleterious effect on the foundation.

This effect and the damage it can cause will be eliminated if the homeowner diverts rain water away from the area by installing underground downspout extensions.  It is possible to extend downspouts aboveground but this practice usually results in inadequate diversion, attachments that are knocked off by landscapers or children playing or unsightly plastic tubing snaking all over the lawn.

Putting in underground downspout extensions will ensure that the downspouts discharge a proper distance from the foundation and the extensions will remain undisturbed regardless of external conditions or activities.  Water that would otherwise end up next to the foundation (and then in the basement) will be carried far enough from the home to prevent it from causing damage.

Installation by a basement waterproofing professional will ensure that the downspout extensions are equipped with a proper debris filter, sloped to prevent back-ups and clogs and made with the right materials.  Also, a pro will make sure that the discharge of water is properly managed, including tying the extension into existing storm sewers when local codes require.

Landscapers, handymen and others who aren’t experts in yard drainage but claim to be able to install underground downspout extensions often use substandard materials and make damaging errors in locating the extensions.

At U.S. Waterproofing, we understand the importance of managing water outside the home and have installed miles of underground downspout extension to help homeowners divert rain water from their foundations.  Why not ask for our free advice about keeping your foundation (and your basement) dry?

Interested in knowing more about how underground downspout extensions will divert rain water away from your foundation?  Please post your questions in the Comments box below.

Tags: divert rain water, underground downspout extensions

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