What is a French Drain System?

If you have a soggy yard or a wet basement, the solution may be an exterior French Drain system, a channel that collects water and diverts it safely away from your house.

Water always flows downhill and by the easiest route possible. The basic concept behind a French Drain System is a slightly sloped trench filled with round gravel and perforated pipe that’s used to divert underground or above groundwater away from your house.

A drain system, may be used to prevent water from penetrating a building foundation, to distribute water such as behind retaining walls to relieve ground water pressure, surface water, standing water and soggy yards where children play, to name a few.

How does a French Drain Work?

French drains work by providing an easy channel for water to flow. Surface and subsurface water runs through the spaces between the round gravel and into the perforated pipe at the bottom of the trench. Installers place the pipe with the holes facing down so the perforations don’t get clogged. Water then travels freely through the pipe, which empties a safe distance from the house. The trench bottom should be sloped about 1 inch for every 8 feet in the section you want water to flow. Depending on the situation, the water can be diverted to a low-lying area of the property, a drainage ditch, a dry well, or the street.

Sherwood Landscape constructs a French Drain through to the storm drain in a way that will not fracture the drain basin. We core drill clean through 12” concrete. Our trench for the French Drain is always pitched which helps the water flow down the slope. The pipe that is put down can absorb water through it. To avoid the French drain being plugged full of dirt, we cover the pipe with fabric and trench stone to eliminate the chance of any dirt or debris from getting in the drain.

We can tie in the downspouts directly from the house right into the French Drain which helps keep the yard free of soft spots and areas that can become overly saturated. Our French drains are built to last the life of the house.

French Drain Sizing Considerations

Depending on the expected level and volume of rainwater or runoff, French drain systems can be widened or also founded on 2 or 3 underground drain pipes. Multiple pipes also provide for redundancy just in case one pipe becomes overfilled or clogged by a rupture or defect in the piping. A pipe might become overfilled if it is on a side of the drain which receives a much larger volume of water such as one pipe being closer to an uphill slope or closer to a roofline that drips near the French drain. When a pipe becomes overfilled water can seep sideways into a parallel pipe as a form of load-balancing so that neither becomes slowed by air bubbles as might happen in a full pipe with no upper air space.