French Drain Soakaways – What are They, How to Install Them

Do I need a French drain?

Does you garden or outdoor area become water logged? Is suface water after rain an issue? Water logged areas near to buildings? Then a french drain or soakaway may be what you need.

What is a french drain?

A french drain is a trench filled with stones created to move water away from water logged areas near buildings. It stops water building up in one area by moving it slowly through its channel. A soakaway is a system to help alleviate surface water build up; by allowing water to run into  and be contained in one area unerground. Then allowing it to disperse in the ground. Helping with ground stability. French drains move water away from specific areas to prevent erosion.

How does a french drain work?

French drains are a channels that water can move through from a waterlogged area, or move water away from buildings. They are filled with stones and allow water to disperse along its length or through a perforated pipe to a new location.

How do you install a french drain?

  • Make sure you have planned and sited your french drain effectively. Check distances from buildings and be sure to check that the end of the trench is suitable.
  • Make sure you have everything you need beofre you start. Spade? Geotextile? Aggregate? Helper?
  • It really is as simple as digging a 1 metre* (as deep as you can until you hit the water table really) trench along the perimeter or ideal location in the garden / driveway usually about 500mm wide.
  • Keep back some of the soil excavated to back-fill later.
  • Make the trench as uniform as you possibly can. Depending on the width and depth you then need a non-woven fleece membrane to line the trench and prevent soil and silt clogging your new soakaway, we have the perfect solution in 1.1 and 2.25 metre widths to line the trench. If you have only an issue with water being absorbed slowly you can dig you trench a little shallower.
  • Once the trench is fully lined with your geotextile membrane including sufficient overlap (300-500mm) you then need to fill the bottom of the trench with clean stone. You can buy clean stone most cost effectively from any local builders merchant or even B&Q; make sure its not too big at 10-30mm in size. To allow water to filter through easily.
  • Now wrap the fleece membrane around and over the stone back-fill again keeping an overlap on the seams and back-fill to ground level with some of your soil you dug out initially.

Do I need to upgrade my French Drain ?

If you fear that your ground is not permeable enough to soakaway properly you can consider adding in an upgrade in the form of some perforated land drain pipe. This land drain adds benefit as it has hundreds of little holes and when placed in the middle of your clean stone black fill it takes all the water form the stones and surrounding area and runs it to more permeable parts of your install and if needed to a surface drain or large soakaway. The geotextile membrane and clean stone filter the water so your perforated pipe should not become clogged and will take the water away and prevent flooding. It’s the perfect, relatively easy to install solution. All made possible by some simple non-woven filtration membrane.

Any queries, please contact us –

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