French drains which, despite their name, originated in america, essentially work by offering invasive groundwater with a path of least resistance by means of 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 Effects of Draining Land with Stones, Wood, Plows, and Open Ditches, and Especially with Tiles.
Nowadays, French drains are generally used to combat flooding problems caused by surface or groundwater that the home owner might be having, especially affecting their lawn, foundation or basement. Also, they are sometimes utilized to drain off liquid effluent from septic tanks.
The fundamental design, a gravel-filled trench, is simple but for it to continue working over the long term, it’s crucial that it be well executed.
Flooding troubles are usually connected with sloping ground, non-porous clayey soil, or a combination of the 2. As an example, should your property is built over a slope together with your neighbors’ house occupying a lot higher the slope, heavy rainfall can precipitate an accumulation of groundwater rushing down off their property and onto your own. If your soil is struggling to absorb all that water, you could very well experience harm to your house’s foundation, or leakage in to a crawlspace or basement below the ground floor of your home.
A linear French drain is a straightforward, inexpensive means to fix such a problem. In this particular scenario, it behaves as a moat that protects your home by intercepting the groundwater rushing along the slope and directing it around and from your house’s foundation.
A linear French drain is actually a doable D.I.Y. project, in the event you don’t mind doing a bit of backbreaking work (this will involve digging a trench, which in the end is really a thing closely similar to a ditch) and you have the appropriate 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 down to the nitty-gritty both how to develop a French drain, and how it works. To begin with, you’ll need to dig an L-shaped or U-shaped trench system, 6″ wide and 24″ deep, 4 to 6 feet from the house. It’s important never to build the drain too nearby the house because, if you do, you’ll be bringing water facing the building blocks, which is exactly what you don’t want.
The main leg from the trench system needs to be dug up the slope from the house. For any U-shaped French drain, it needs to be level and connected to two pipes on both sides of the house with 90 degree PVC elbow joints. To have an L-shaped drain, the primary 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 your house, also connected through a 90 degree PVC elbow joint.
When you find yourself designing your drain system, you would like to make gravity work for you. Just like a river, groundwater flows downhill, so you’ll have to work alongside natural slope of your residence and, when possible, possess the exit pipe appear above ground to offer the groundwater an easy exit point.
Once you’ve decided on the layout in the system and done the heavy work of digging the trenches, it’s time to install the working elements of the drainage system: the gravel and pipes. To begin with, 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 primary layer of gravel, with all the holes pointing down, and then fill in the trench with more 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. The next time there’s a huge rain, excess ground water will enter your newly installed French drain and become diverted around your property 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 the piping be wrapped in a geotech sock to stop it from becoming clogged with silt. I don’t recommend doing either. Should you be planning to use geotech fabric anywhere, the place to put it would be along with the trench to stop silt and sediment from filtering down from above and filling in the air spaces in between the gravel. A lot of the water that enters a French drain is groundwater flowing sideways underground, not downwards through the surface. Groundwater will not be silty, it has already had the silt and sediment filtered from it because it trickled down through the topsoil. In the event you doubt this, just think about whether underground spring water and well water are clear or muddy. Both of them are needless to say usually magnificent because soil is actually a natural water purifier.