Install a Drainage Swale

How to Install a Foundation Drainage Swale

Design & Tips

Learn about installing a foundation drainage swale and how it helps your residential foundation.

By Frederick Marshall
March 5, 2013

Often overlooked and underused, drainage swale systems are simple and inexpensive foundation maintenance options that Advanced Foundation Repair often recommends for homes located in Dallas, Texas.

Foundation Drainage Swale Definition

A foundation drainage swale system, also known as a vegetated swale or grass swale, is just a fancy term for a wide, shallow ditch that carries away run-off water from rain, sprinklers, and so on. From a landscaping perspective, short swales hardly show because of their wide and shallow design and are often the easiest drainage system to install. They can help prevent the possible need for expensive foundation repairs and are nearly maintenance-free.

To Start?

Do you need a foundation drainage swale? One easy test is to check one hour after a rainfall. Look to see if there is a standing pool of water no more than 10 feet from the home’s foundation. Standing water can cause soil to expand, which can cause undue pressure on foundations, while excess pressure on the foundation may cause foundation damage that requires expensive foundation repair. Once installed, residential drainage swale designs are virtually maintenance-free as they blend in with the grass and are easy to mow.

Foundation Drainage Swale Tips

Here are a few swale design tips for DIY homeowners looking to install a residential drainage swale:

• Because swales must slope downhill, on flat lawns, they should be deeper as they get longer. Swales must slope at least 1 inch for every 10 feet of length. With this in mind, map out where the drainage goes by marking the ground along where the center of the swale will run.
  Use a shovel and cut a trench along where the center of the swale will be. Dig the trench, sloping the bottom down at least 1 inch for every 10 feet of length. If sod will be placed in the swale, lower the entire trench 2 to 3 inches.
• Use a shovel and cut a trench along where the center of the swale will be. Dig the trench, sloping the bottom  down at least 1 inch for every 10 feet of length. If sod will be placed in the swale, lower the entire trench 2 to 3 inches.
• Next, mark the edges of the swale. The goal in locating the edges of the swale is to keep the sides of the swale sloped gently enough to keep the swale from being noticeable.
• Using a shovel, gently lift up the grass in the swale.
• Set the grass pieces aside.
• Check on the pieces often while working to ensure they stay moist. Water them if needed.
• Dig a trench in the marked area. The trench should be a shallow V shape leading away from the foundation to an adequate runoff point, such as a French drain or street.
• To keep the swale from being too noticeable, it should gradually widen as it approaches the final drainage point.
• Wet the soil in the swale.
• Place the grass pieces back into the dampened swale by laying them smoothly out and pressing firmly back into the damp soil.
• Make sure the grass is thoroughly watered.
• Make sure that nothing is blocking water flow as it moves out to the street or to a drain.

Frederick Marshall is the CEO of Advanced Foundation Repair, LLC, a foundation repair company specializing in home repairs from the foundation up, including foundation repair, foundation drainage, exterior foundation waterproofing, foundation irrigation, and plumbing services. Advanced Foundation Repair has specialized in the foundation repair needs of Texas homeowners for over 100 years. Connect with him on Google+.