What is a French drain?

A French drain, originally thought to have been founded in France was a drainage system design to create surface or foundation drainage to directed water from one area to another.  The first external French drain system for yard drainage was installed without drainage pipe or weeping tile. A trench was dug one to two feet down and filled with stone varying size. The purpose was to create a drainage system to prevent water from pooling in one area and typically installed from a high to lower location. The trenches were dug by hand or with machine and lined with clay then filled with stone. The French drain system was installed before drainage pipe or weeping tiles were created.

Interior French drain system

Many people ask what is a French drain, and it seems that over the years the understanding of a French drain system and the French drain design have dramatically changed. With the French drain purpose of moving water from one location to another for year drainage and foundation drainage, the solutions have evolved dramatically. The interior French drain system or the Internal drainage system sometimes know as (internal waterproofing) still focuses on the original purpose of moving water from one location to another. The interior French drainage system involves breaking the basement floor along the perimeter foundation walls and sometimes trenching into the center of the floor as well. The French drainage design involves trenching below the floor allowing room for drainage pipe or weeping tile. The best solution is to connect the weeping tile or drainage pipe to a new sump pump for proper discharge. Once the trench is dug and the weeping tile installation is done the system is filled with 3/4″ clear gravel and covered with a dimple board membrane extending up the foundation walls. New concrete is poured over the trench flush with the existing floor.  This French drain design has been around for decades for foundation drainage. For more information on the interior French drainage system or a free estimate please call us or send us an email.

External French drain system

The external French drain system has evolved over the decades however it is still used for many of the same purposes. In 1859 the book Farm Drainage was written by Henry Flagg French, the book described how roofing tiles were used to act as drainage pipe for an external French drain. Later drainage pipe and weeping tile were created for a new drainage system to hit the market. Today the external French drain system is still used to move water from one location to another for yard drainage and foundation drainage. Today’s technologies allow for a more advanced drainage system allowing the water to travel more efficiently. The new French drain design consists of excavating a trench from one area to another or to a dry well. The trench is then lined with a dimple board where the weeping tile or drainage pipe is placed on top. The French drain is then filled with 3/4″ clear stone to provide additional drainage. Once the trench is filled it is then covered with a geotextile filter cloth (garden cloth) to help prevent soil from clogging the new French drain system. The new French drain design can then be covered with soil for aesthetic purposes. The new weeping tile installation process also has a geotextile filter sock where French drain pipe typically does not. If you have more questions on what is a French drain and would like to learn more about our French drain design with drainage pipe or weeping tile installation please call us for more details.