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Prepare your garden now for heavy rains

Torrential rains and flooding seem to be the norm these days for many areas around the country, so make sure that your garden can cope by installing a French drain.

04/06/2019

With torrential rains and flooding occurring in many places around the country, making sure your garden can cope with excess water will keep your home and your family safe. One way to ensure your garden doesn't get waterlogged is to install a French drain.

Having installed my own French drain quite a few years back, downpours and cloud bursts haven't been much of a problem in my garden since the installation.

 

 

What is a French drain?

Named after a farmer by the name of Henry French, a French drain is a dug-out trench that is filled with gravel that also contains a perforated pipe that redirects surface water away from an area. French drains are used to prevent ground and surface water from penetrating or damaging building foundations.

 

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Why you need a French drain

If you have problems with surface water sitting on top of your lawn or areas that get flooded during a rainstorm you need a French drain to fix this.

Installing a French drain

If you need to install a French drain in your garden, I have included a video below that will guide you step-by-step through the process. The video doesn't give metric measurements, so I have added these below, as well as links to materials you will need for this project. If you don't fancy doing this as a do-it-yourself project, get in touch with a company that offers French drain installation.

 

 

YOU WILL NEED:

Spade and shovel (spade to cut and shape and a shovel to remove)

Pickaxe if your ground is hard

Landscaping fabric (geotextile)

Wheelbarrow

Tamper

String line and staves

GOOD TO KNOW: Have the plans for your property on hand so that you know where any utilities or sewer lines are located, or get in touch with your local municipality to obtain these details. If you already know where these are located you will have to work the French drain away from these.

 

 

HERE'S HOW:

1. Mark the location for the French drain in order to dig a trench. The trench needs to be approximately 50cm wide and about 60cm deep, and also allow a slope from front to back. Set any grass aside so that this can be re-planted once the trench is done.

GOOD TO KNOW: Since water always flows downhill, the basic concept behind a French drain is to dig a slightly sloped trench that diverts water away from your house. The trench needs to be sloped about 25mm for every 2 ½ metres in the direction you want water to flow.

2. The trench for installing the French drain needs to run outside a property and,  according to SA Damp it should drain into an area located well away from any built structure or it can be diverted to a drainage ditch or dry well. 

3. After digging out the trench you need to adjust for the slope. The ideal slope is 25mm for every 2 ½ metres - in the direction you want water to flow. Set up a string line and set this for the slow, digging out and adjusting the trench as you move towards the end. Use your spade or shovel to remove or add soil to accommodate the slope.

 

GOOD TO KNOW:  When adding soil back into the trench, use a tamper to compress.

4. Line the bottom of the trench  with landscaping fabric (geotextile) and place a 6 to 8cm thick layer of gravel over the top of this. Spread the gravel to maintain the proper slope.

5. Place the perforated pipe over the top of the gravel bed.

6. Place a piece of mesh in the end of the pipe to prevent blockage and for easy clean-out.

7. Cover the pipe with gravel and wrap over the top with landscape fabric to close off. Fill with soil and top off with grass sod.

For more information, watch the video below for details.

 

 

 

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