French drains which, despite their name, originated in the United States, 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’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 Results of Draining Land with Stones, Wood, Plows, and Open Ditches, and Especially with Tiles.
Nowadays, French drains are typically utilized to combat flooding problems brought on by surface or groundwater that a property owner could be having, especially affecting their lawn, foundation or basement. They are also sometimes utilized to drain off liquid effluent from septic tanks.
The essential design, a gravel-filled trench, is simple however for it to go on working on the long haul, it’s important that it be well executed.
Flooding issues are usually connected with sloping ground, non-porous clayey soil, or a mixture of both. For instance, should your property is constructed on a slope with your neighbors’ house occupying a whole lot higher the slope, heavy rainfall can precipitate an accumulation of groundwater rushing down off their property and on your own. If your soil is struggling to absorb everything that water, you could very well experience damage to your house’s foundation, or leakage into a crawlspace or basement underneath the ground floor of the house.
A linear French drain is a simple, cost-effective answer to this kind of problem. In this scenario, it behaves as a moat that protects your property by intercepting the groundwater rushing down 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, should you don’t mind performing some backbreaking work (this will involve digging a trench, which after all is actually a thing closely akin to a ditch) and you will have the appropriate tools and materials (1″ round washed gravel, 4″ PVC pipe with drainage holes, a trenching spade or power trencher and a builder’s level)
So, let’s get right down to the nitty-gritty each of how to construct a French drain, and how it operates. To begin with, you’ll have to dig an L-shaped or U-shaped trench system, 6″ wide and 24″ deep, four to six feet through the house. It’s important to not build the drain too nearby the house because, should you do, you’ll be bringing water against the foundation, which is precisely what you don’t want.
The primary leg in the trench system needs 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 both sides of the home with 90 degree PVC elbow joints. For the L-shaped drain, the main leg should slope down, in a pitch of at least 1/8 inch per foot of fall, for the second leg that will run alongside the house, also connected by means of a 90 degree PVC elbow joint.
When you are 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 do business with natural slope of your residence and, when possible, hold the exit pipe emerge above ground to provide 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 and energy to install the working elements of the drainage system: the gravel and pipes. To begin with, tamp down any loose soil in the bottom from the trench and line it with 1 to 2 inches of gravel, lay the PVC pipes on the top of this primary layer of gravel, using the holes pointing down, and then complete the trench with additional gravel, to 1 inch below ground level. Then all you want do is cover the trench with sod or sdxgas decorative touch of your choosing. And you’re done. The next time there’s huge rain, excess ground water will enter your newly installed French drain and become diverted around your home and discharged after the exit pipe or pipes.
It’s commonly recommend that a French drain be lined with geotech fabric as well as the piping be wrapped in a geotech sock to avoid it from becoming clogged with silt. I don’t recommend doing either. If you were going to use geotech fabric anywhere, the place to place it would be on the top of the trench to prevent silt and sediment from filtering down from above and filling inside the air spaces between the gravel. A lot of the water that enters a French drain is groundwater flowing sideways underground, not downwards from your surface. Groundwater will not be silty, it has already had the silt and sediment filtered from it since it trickled down through the topsoil. In the event 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 really a natural water purifier.