Long Island Basement Waterproofing – Family Owned and Operated

French Drain

Hydrostatic Pressure and the French Drain System

Rising groundwater is one of the most common causes of water intrusion. As the water pressure builds on the outside of a home, it will push water through even the tiniest cracks and spaces in your basement floor and walls. Like any fluid, water is constantly seeking an area of lower pressure and in this case, the area of lower pressure is the inside of your basement.

The goal of a pressure relief system, or french drain, is to give this water a place to go — a place other than your basement floor. In some parts of the country, this system is called a drain tile, but in the Northeast, it is more commonly known as the French drain.

How does a French drain work?

french drain installation process acm basement waterproofing

Click on the French Drain diagram above for a closer look at the elements of our French drain system, how it works, and how it is installed.

One of the biggest problems in basement waterproofing is designing a French drain system that can deal with incoming water no matter where it comes from. At first, it may seem like the best option is to simply seal up the structure so that water cannot enter. This option is problematic, however, because water will always find some other way of entering the house—the water has to go somewhere and it wants to go to a nice, open, low-pressure zone, i.e. the basement.

Rather than attempting to seal the home, thereby giving the water no place to go, the French drain system receives incoming water so it can either drain into the ground or be pumped outside.

Deep Pressure Relief with a French Drain from ACM

An ACM French drain (named after Henry French) consists of a flexible perforated pipe that is installed below the floor around the perimeter of the basement. At the very edge of the floor, where the floor meets the wall, we leave a 3/4 inch drain channel; if water leaks in through the walls, it will enter this channel and trickle into the perforated drain pipe.  As this drain pipe begins to fill with water, the water will flow into a sump where it can safely be pumped from the basement. If water enters through the footing joint, it will end up in the french drain pipe. Even if the water table begins to rise in the middle of the basement, this too will be drawn toward the French drain’s low-pressure zone located beneath the basement floor.

See Also: French Drain Systems vs. Pressure Relief Systems

What’s the difference between a French drain and a pressure relief system?