Step by Step: How to install a French drain

August 21, 2017 -  By

Drainage issues in a lawn can cause an array of problems, like disease and damage to a home’s foundation. One way to get rid of excess water is to install a French drain. A French drain consists of a perforated drainage tube placed into a trench filled with loose gravel or rock that’s designed to take water away from wet areas and disperse it into dry areas.

Before installing a French drain, it’s important for contractors to figure out what kind of drainage problems they’re dealing with. There are three main types of drainage issues that occur in turf: swampy ground, water that accumulates into a small lake and water that makes a small flowing river. French drains are often the best solution in swampy areas, where turf stays wet and squishy even days after rainfall. Dry wells, the vertical version of a French drain, also can help resolve other drainage issues.

For safety reasons, contractors should work with their clients’ municipal or public agencies to locate all underground cables, pipes and other installations prior to digging a trench. It’s also important to consider whether the water to be drained is coming from a hazardous source.

Follow these steps to properly install a French drain.

Step 1

Using a power trencher or trenching shovel, dig a trench at least 8 inches wide and 8 inches deep at a 1 percent grade. Begin your trench near the middle of the lawn’s wet area, ending it in a dry area.

Step 2

Line the trench with landscape fabric to keep out roots and soil, leaving at least 10 inches of excess fabric on either side of the trench. Fill the trench with 1-2 inches of loose gravel.

Step 3

Place the perforated drainage tubing on top of the gravel, making sure the holes are facing downward to maximize drainage. Fill the remaining trench with more gravel and cover it with soil and grass.

To download a PDF of this page to use as a training tool for your team, click here.

Source: KG Landscape Management; kglandscape.com
illustrations: David Preiss

LM Staff

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