In our Santa Cruz climate, proper drainage is especially important if you want to keep your landscaping and home protected from water damage. An overabundance of water can drown certain plants, harbor disease, ruin the soil beneath turf, compromise the structure of retaining walls and have negative impacts on wood siding. It can even affect the foundation of your home. One of the most efficient ways to prevent these damages is by installing a French drain system into your property.
So what is a French drain exactly? Also known by multiple other names including curtain drain, land drain, French ditch, sub-surface drain, rock drain or drain tile, the French drain is a critical component in landscape design for areas that are prone to water accumulation. It is essentially a trench filled with rock or gravel, filter cloth, and perforated pipe that collects excessive water underground and diverts it away from the area you are protecting.
French drains are typically used along building foundations and behind retaining walls where subsurface water can accumulate. The main cause of retaining wall failures is the weight of the standing water behind the wall, which adds too much pressure on the wall and basically pushes it over. Along with causing pre-mature wood rot, water is a huge problem for wooden retaining walls.
The French drain trench is typically only 6-12 inches wide. It’s important to identify the proper elevation to install the system and have enough slope in the pipe to keep the water moving in the desired direction for your specific project. The depth of the drain is determined by the structure you are trying to protect.
When correctly installed, the perforated piping in the French drain collects the water and empties it to a lower portion of the property where it will not cause damage to structures. In some cases where there is not enough slope to the appropriate drainage location, a sump basin and pump can be installed to move the water to a suitable location.
Once the ideal location and depth of the French drain have been determined, it is time to start digging. After the trench is excavated to the proper depth with enough slope, the installation of filter fabric, drain rock, and perforated pipe is carried out. A common mistake is to install the perforated pipe with the holes facing up, but this is actually incorrect. The holes should face down to allow the water to percolate up into the pipe and be carried away to the correct location. Another piece of advice: never connect other drains into the French drain, including downspouts from the roof or surface drains that may contain debris. This can clog up the perforated pipe and cause the French drain to fail.
With so many variables involved in determining if a French drain is the right solution for you, it’s important to contact a landscape professional that has proven experience in assessing drainage issues and knowledge of various drainage systems to evaluate your property and its specific challenges. Don’t let water concerns bog down your landscaping, protect against them with a French drain!