French Drains

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French Drains: An Effective Solution

Maybe you have an area in your yard that holds water after a rainfall? This is a common problem, and something that Phoenix Home Services can solve. Over the years we have solved hundreds of customer's problems with yard drainage. A surprisingly simple but incredibly effective solution for problem exterior drainage issues is a French Drain.

Are French Drains REALLY French?

Answer: No. French Drains were not invented in France; the name comes from a 19th century farmer from Concord, Massachusetts named Henry French.

French Drains: How do they work?

A French Drain is simple in concept but it does take skill and experience to properly lay one out and install it. The main purpose of a French Drain is to divert water from where you don't want it- whether pooling in your yard or seeping into your home- to where it can safely drain away. Residential yards in Northern Virginia are typically composed of dense clay underneath a surprisingly thin layer of topsoil. The density of the clay prohibits water absorption, especially when water comes in heavy volumes over a short period of time. During an intense storm, the water can flow sideways along the top of the clay "shelf" instead of seeping down into the ground as would be expected. A properly installed French Drain creates an area where water moving down from the surface as well as upwards from the water table and laterally in the clay shelves can go due to water pressure being relieved in the spaces between the aggregate stone in the trench and the holes in the drainage pipe it encases.

Where are French Drains Typically Located?

In a nutshell: A French Drain intercepts and drains water via an underground pipe to a safe drainage location. They will be located in areas of the yard and against the home where water collects and pools and be extended to a safe and effective drainage area. The French Drain collects and redirects surface and ground water to prevent it from penetrating or damaging Building Foundations, Basements, Garages, etc. The French Drain technique may also be used to distribute water such as that which flows from the outlet of a typical septic tank sewage treatment system. French Drains can also used behind retaining walls to relieve ground water pressure. It is a time-tested technique that can be put into place to solve any number of issues that pertain to water damage as a result of poor drainage.

The Phoenix Technique

With more than 25 years of experience behind us we have refined the French Drain system to a science. Outlined below are the basic techniques that Phoenix Home Services has devised:

A Phoenix Home Service French Drain is a gravel filled trench which holds one or more 4" submersed pipe(s). Some contractors install them without a pipe at all - rather simply a trench filled with gravel! That will NOT work in our region's soil conditions. Phoenix builds French Drains in a way that is best suited to issues common with Northern Virginia and Washington DC yards and their water problems, and that means using a pipe!
A common difference between the Phoenix Technique and others is we build trenches that are at least eight inches wide, and usually extend up to twelve inches of width, as opposed to the more commonly used six inch trench. A wider French Drain will last longer. The capacity to collect and disperse water is better when larger, and it is easier to dig and grade a wide French Drain, especially when a deep one is required. Let's look at each of these areas individually.
A wider French drain will last longer because the primary cause of failure in a French Drain is silting up of the spaces between the #57 gravel by clay and soil - and a wider system simply has more gravel in it and takes longer to clog up. French drains only fail when the gravel becomes full of Virginia clay or when the drainage pipe becomes full of plant roots and the bigger the trench, the less potential there is for it to get clogged up!
To further prevent clogging we cover the trench in landscape cloth and wrap the pipes in drain sleeve fabric. Seemingly simple concepts to be sure but many contractors don't take these steps when building a French Drain system.

Re-Cap

The capacity to collect and disperse water is better in a wide French Drain. Think about how much more water can flow through a 12 inch channel as compared to a 6 inch channel. With a French Drain you want to allow as much water to soak into the soil in dryer parts of the yard, and a length of French drain that is 12 inches wide has twice the drainage area as a 6 inch wide trench, pretty simple right? But surprisingly most contractors dig a 6 inch trench, giving you half the bank for your buck! There are also small dry wells that can be added to the bottom of the French drain trench as needed and it is much easier to dig these in a wider trench.

French Drains: It's Common Sense

So why do some contractors build smaller drains? It's simple really, digging a French Drain trench out of Virginia clay is HARD WORK! The same thick clay that causes so many water problems in the first place is hard to get through and heavy to haul away. Remember, installing a French Drain is much different than normal trenching in that much of the dirt will not go back into the trench because of the gravel and the pipe. If you have ever tried to plant a bush or a tree and had to work your way through the clay that is beneath the topsoil in your yard you can get an idea of the amount of work it takes to dig a 12" wide by 12" deep by 50' long trench.

It's not just a matter of digging a trench. Part of the art of building a perfect French Drain is grading the trench so the water is collected and flows as effectively as possible. It seems simple but it is critical and laborious to get the trench angle spot-on so gravity can do its job and move that water through the pipe! That is the whole working purpose of the French Drain... to get water absorbed into a pipe and then let gravity and water pressure do the work. It takes a lot of experience to set the French Drain up so those two forces are working to move the water where it needs to go when it needs to get there.

For more information please fill out the estimate request form on this page and one of our trained consultants will be happy to meet with you and answer all of your questions.

French Drains Serving All of Northern Virginia and DC