French drains which, despite their name, originated in the usa, essentially work by offering 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’re 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 Outcomes of Draining Land with Stones, Wood, Plows, and Open Ditches, and particularly with Tiles.
Nowadays, French drains are generally employed to combat flooding problems caused by surface or groundwater which a home owner could be having, especially affecting their lawn, foundation or basement. They are also sometimes used to drain off liquid effluent from septic tanks.
The essential design, a gravel-filled trench, is easy however for it to continue working within the long term, it’s essential that it be well executed.
Flooding troubles are usually related to sloping ground, non-porous clayey soil, or a mix of both. As an example, if your property is constructed on the slope with your neighbors’ house occupying a great deal higher in the slope, heavy rainfall can precipitate an accumulation of groundwater rushing down from their property and on your own. If your soil is unable to absorb all that water, you could very well experience damage to your house’s foundation, or leakage in to a crawlspace or basement below the bottom floor of your home.
A linear French drain is an easy, inexpensive answer to this kind of problem. In this particular scenario, it works as a moat that protects your house by intercepting the groundwater rushing down the slope and directing it around and out of your house’s foundation.
A linear French drain is actually a doable D.I.Y. project, should you don’t mind doing some backbreaking work (this will involve digging a trench, which in the end is really a thing closely akin to a ditch) and you have the correct tools and materials (1″ round washed gravel, 4″ PVC pipe with drainage holes, a trenching spade or power trencher along with a builder’s level)
So, let’s get right down to the nitty-gritty each of how to develop a French drain, and the way it works. First of all, you’ll need to dig an L-shaped or U-shaped trench system, 6″ wide and 24″ deep, 4-6 feet from the house. It’s important never to build the drain too nearby the house because, should you do, you’ll be bringing water against the foundation, which is exactly what you don’t want.
The primary leg of the trench system should be dug the slope from your house. For a U-shaped French drain, it needs to be level and connected to two pipes on both sides of your home with 90 degree PVC elbow joints. For the L-shaped drain, the primary leg should slope down, in a pitch of at the very least 1/8 inch per foot of fall, towards the second leg which will run alongside the home, also connected by means of a 90 degree PVC elbow joint.
When you find yourself designing your drain system, you would like to make gravity be right for you. Like a river, groundwater flows downhill, so you’ll have to work alongside natural slope of your property and, when possible, possess the exit pipe appear above ground to give the groundwater a fairly easy exit point.
Once you’ve decided on the layout of the system and done the heavy work of digging the trenches, it’s time for you to install the working parts of the drainage system: the gravel and pipes. First of all, tamp down any loose soil in the bottom in the trench and line it with 1 to 2 inches of gravel, lay the PVC pipes on top of this first layer of gravel, with all the holes pointing down, and then fill in the trench with additional gravel, to 1 inch below ground level. Then all you need to do is cover the trench with sod or sdxgas decorative touch of your choosing. And you’re done. Next time there’s a huge rain, excess ground water will enter your newly installed French drain and stay diverted around your house and discharged at the conclusion of the exit pipe or pipes.
It’s commonly recommend that a French drain be lined with geotech fabric and also 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 likely to use geotech fabric anywhere, the area to put 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 involving the gravel. Most of the water that enters a French drain is groundwater flowing sideways underground, not downwards from the surface. Groundwater is not really silty, it offers already had the silt and sediment filtered from it since it trickled down with the topsoil. Should you doubt this, just consider whether underground spring water and well water are clear or muddy. Each of them are obviously usually crystal clear because soil is really a natural water purifier.