What is a French Drain and How to Do It by Yourself?

Being on terra firma means you need to pay special attention to ensuring your home is waterproof. One such method is the French drain, named after Henry Flagg French, a lawyer and former assistant U.S. treasury secretary from Concord, Massachusetts, who popularized the technique thanks to his book Farm Drainage (1859).

As a graduate of Dartmouth College and Harvard Law School, French enjoyed more than just rules and regulation. He was an agriculture enthusiast and avidly experimented to increase scientific application to farming, particularly in the study of soil quality. The techniques used by farmer discussed in his published work, despite dating to nearly 160 years ago, still hold true today. The French drain is no exception.  

Historical French drains were simply ditches, dug out from an area of elevation to lower ground, and filled in with gravel. At the time, French was constructing drains for his own farm and used roofing tiles in conjunction with a trench. Perforations were later added to these tiles with improvements in the process having been made over the years. French drains are now far more specialized than their predecessor, which is why they remain a popular waterproofing method for not only farmers, but homeowners too.

What is a French Drain and How Does It Work?

A French drain is simply a sloped trench that is lined with fabric with a pipe and gravel running through it. Its purpose is to steer water away from your home or other structures on your property.

Water naturally flows downhill, which is the route of least resistance. So during a heavy rain, water will run into the gravel-filled trench before reaching the perforated pipe and flows through the pipe, away from your basement. The water is then emptied out, whether it be on the street or in a drainage ditch.

A DIY French drain is actually quite easy. All it takes is a few materials: water permeable landscape fabric, a perforated plastic drain, gravel or rock, and a shovel.

The process of building a French drain is not complicated, but careful attention is necessary. Work should begin on a downhill slope so that the trench can draw water away from your home just by the force of gravity. Before digging, think safety first. Locate any underground cables and pipes that run under the yard.

Then plan the route of your drain. Landscaping paint can help mark out the path. Make sure your runoff water doesn’t empty onto a neighbour’s land. Position it at least one meter away from walls and fences and steer clear of posts and plants like tree roots and shrubs. Depending on your municipality, digging may require paperwork. Consult your municipal office for information on the regulations pertaining to your neighbourhood.

Once the above steps are completed, you can start digging your trench, the width and depth of which will depend on the severity of the drainage issue (consult with a professional). The standard size is about 15 centimeters (6 inches) wide and 46 to 61 centimeters (18 to 24 inches) deep. Hiring a surveyor or a professional specializing in waterproofing techniques to help with the planning stage is one way of ensuring you are on track.

Position the trench so that it is built on a downhill incline and regularly check you are digging in a downward direction. The trench is then lined with landscape fabric. Gravel is added, the pipe is fitted with the drain holes facing down and the opening covered.

At this point, you can be creative by adding a layer of decorative stones. Sometimes, people build their French drain at a slight curve to make the space look aesthetic.

Do You Need a French Drain?

This type of drain is an ideal solution for those with basements that are prone to flooding or have a soggy yard.

Basements: In this case, a deep French drain is recommended by professionals. With a trench running around the home’s perimeter, water is swiftly caught before flowing into your basement. Installation is also possible during and after home construction.  

Yard: For an uneven yard, the drain does not need to be as deeply placed as in the case of wet basements. This type of French drain runs horizontally at a downhill inclination across the property.  

From farmers to homeowners, the French drain has been lending a hand with water diversion for over 150 years. So whatever your waterproofing needs may be, when heavy rains wreak havoc on your basement or yard, this simple, yet effective solution can help. The issues that may surface with a DIY project can easily be mitigated with advice from a professional.