French drains which, despite their name, originated in america, essentially work by providing invasive groundwater with a path of least resistance through which it can be redirected away from a structure or low-lying section of lawn. They are named for a new Hampshire man, Henry Flagg French, who, in 1860, published a book with the intriguing title: Farm Drainage – The Principles, Processes, and Results of Draining Land with Stones, Wood, Plows, and Open Ditches, and particularly with Tiles.
Nowadays, French drains are typically used to combat flooding problems due to surface and/or groundwater which a property owner might be having, especially affecting their lawn, foundation or basement. They are also sometimes employed to drain off liquid effluent from septic tanks.
The basic design, a gravel-filled trench, is easy but also for it to continue working on the long term, it’s essential that it be well executed.
Flooding problems are usually related to sloping ground, non-porous clayey soil, or a mix of the 2. For example, in case your property is made on a slope with your neighbors’ house occupying a lot higher up the slope, heavy rainfall can precipitate an accumulation of groundwater rushing down using their property and on your own. Should your soil is not able to absorb everything that water, you would likely experience harm to your house’s foundation, or leakage right into a crawlspace or basement below the bottom floor of the home.
A linear French drain is a simple, inexpensive solution to this kind of problem. In this scenario, it behaves as a moat that protects your home by intercepting the groundwater rushing on the slope and directing it around and away from your house’s foundation.
A linear French drain is really a doable D.I.Y. project, if you don’t mind performing some backbreaking work (this does involve digging a trench, which in the end is really a thing closely similar to a ditch) and you will have the correct tools and materials (1″ round washed gravel, 4″ PVC pipe with drainage holes, a trenching spade or power trencher as well as a builder’s level)
So, let’s get as a result of the nitty-gritty each of how to construct a French drain, and how it operates. First of all, you’ll need to dig an L-shaped or U-shaped trench system, 6″ wide and 24″ deep, four to six feet from your house. It’s important never to build the drain too close to the house because, should you, you’ll be bringing water up against the building blocks, which is exactly what you don’t want.
The primary leg of the trench system ought to be dug in the slope from your house. For a U-shaped French drain, it ought to be level and connected to two pipes on each side of the house with 90 degree PVC elbow joints. For an L-shaped drain, the key leg should slope down, in a pitch of at least 1/8 inch per foot of fall, towards the second leg which will run alongside the house, also connected by means of a 90 degree PVC elbow joint.
When you find yourself designing your drain system, you need to make gravity be right for you. Just like a river, groundwater flows downhill, so you’ll have to work with natural slope of your home and, if at all possible, have the exit pipe come out above ground to offer the groundwater a fairly easy exit point.
Once you’ve decided on the layout from the system and done the heavy work of digging the trenches, it’s time for you to install the working elements of the drainage system: the gravel and pipes. First of all, tamp down any loose soil towards the bottom from the trench and line it with 1 to 2 inches of gravel, lay the PVC pipes on top of this first layer of gravel, using the holes pointing down, then complete the trench with increased gravel, to a single inch below ground level. Then all you have to do is cover the trench with sod or sdxgas decorative touch of your personal choosing. And you’re done. The next time there’s huge rain, excess ground water will enter your newly installed French drain and be diverted around your home and discharged at the conclusion of the exit pipe or pipes.
It’s commonly advise that a French drain be lined with geotech fabric and the piping be wrapped in a geotech sock to avoid it from becoming clogged with silt. I don’t recommend doing either. Should you be planning to use geotech fabric anywhere, the place to set it would be on the top of the trench to avoid silt and sediment from filtering down from above and filling in the air spaces between the gravel. Most of the water that enters a French drain is groundwater flowing sideways underground, not downwards through the surface. Groundwater is not silty, it provides already had the silt and sediment filtered out of it because it trickled down through the topsoil. If you doubt this, just ask yourself whether underground spring water and well water are clear or muddy. Each of them are needless to say usually magnificent because soil is a natural water purifier.