After a Disaster Roof Repairs 7: Drainage

Publication Number 490-328, August 1996

General

Good roof drainage is probably more important to the foundation of the house than the roof. Water around a foundation is a guaranteed house killer! It seeps into crawl spaces where it vaporizes and rots sills and floors or seeps into basements. Ninety percent of house damage from moisture starts in a crawl space. It is important to drain roofs well to keep water away from foundations. These systems work:

A good method of collecting roof water is a guttering system. The most important thing about the system is where it dumps the water. Splash blocks at downspouts are minimal and often ineffective since they release water too close to foundations. Water should not be released within three feet of the foundation or, better still, 10 feet away. Downspouts emptying into a drain tile system are best.
Another system that works with a wide (three feet or more) overhang is no gutters at all with a treated (gravel) ground surface where drainage water strikes the ground. In turn, the ground must slope away from the structure, on all four sides at a minimum 2 percent slope to carry water away from the foundation immediately.

Based on information developed by Clemson Cooperative Extension following Hurricane Hugo. Revised for Virginia audiences by Virginia Cooperative Extension.

For more information, contact your local office of Virginia Cooperative Extension.

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