Roof Run Off: Best Ways to Drain

Excessive water runoff is a major problem in today’s communities. As impermeable surfaces, such as concrete and asphalt, have increased, and natural vegetation has decreased, flooding results. Excess runoff pollutes the communal water supply and damages construction.

Your roof is designed to be an impermeable surface that protects your house and allows the water to run off. According to Chris Lowe of Kidd Roofing in Austin, “Excess water must be channeled away from the house and drained or absorbed.” There are several ways to increase the capacity of your property to absorb excess runoff. Proper drainage of runoff protects your house, your neighbors’ property, and the community at large.

Gutters and Downspouts

The first line of defense against runoff is gutters and downspouts. Soil that is not kept dry will expand and contract. This can cause the foundation to buckle and heave. Gutters prevent runoff from falling straight down onto the soil next to the house. Downspouts channel gutter water to flow away from the foundation.


Lawns are very poor at absorbing runoff. Consider replacing the lawn with native plants, such as shrubs or wetland grasses. Plant more trees. Trees have extensive root systems that absorb water across a wide area. Their leaves shelter the ground from heavy rainfall.

You can increase your yard’s absorbency by adding compost or mulch to the soil. Adding 2-4 inches of organic material every year helps absorb rainfall and is good for the grass (or other vegetation). Having a lawn is still much better than bare soil, which can dry into hardpan and become almost as impermeable as asphalt. Cover any bare areas with mulch, gravel or wood chips, which will slow runoff.

Replacing Pavement

Another good way to increase drainage on your property is to reduce the impermeable surfaces. These surfaces include pavement, walkways, driveways and patios. For example, you can reduce your paved driveway to two tire strips. Plant grass in the median, or fill it in with gravel. You can line impermeable surfaces with gravel trenches, which will collect water and allow it to soak into the soil.

A more extensive solution is to replace the asphalt or concrete with a permeable substance. Permeable pavers have gaps that allow water to run through into the gravel layer beneath and, ultimately, into the soil. Stone or concrete pavers have a tile-like appearance and can be more or less widely spaced. Plastic pavers are grids that lie over a gravel bed. They are easier to install than concrete pavers. Semi-permeable forms of asphalt and concrete allow some water to soak through. These materials require professional installation.

Reshaping the Landscape?

The contours of your property can be resculpted to channel runoff away from your house and into collection zones. A steep slope absorbs less water. You can terrace any steep slope on your property, so that water descends more gradually. Add swales below the border of each terrace. These ditches, filled with rock, gravel and water plants, will channel water into a dry well or rain garden.

A rain garden is a shallow catch bed filled with fast-draining soil and plants that tolerate wet conditions. Rain gardens must be placed several feet from the foundation and even farther from septic systems or steep slopes. Runoff channeled to the rain garden will be held there until it is absorbed into the soil.

Kidd Roofing in Austin specializes in commercial and residential roofing. They have worked on small projects, such as a family home, as well as large projects, such as the DKR Football Stadium at the University of Texas. Check out their Facebook for more information.

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