What Is A French Drain, And Why Would I Want One?

The French drain is an important part of a home’s drainage system. It guides water away from the foundation walls and any low-lying parts of a property, helping to keep them dry and the basement free of moisture. While it’s probably already helping your foundation, you might want to consider a French drain on other parts of your property, too! 

What Is A French Drain?

A French drain, also known as a weeping tile system, is a trench filled with a perforated pipe and gravel or rock, and this allows water to drain out and away from areas where you don’t want excess moisture. It sits at the foot of your foundation so that when water drains down, the pipe can carry it away. It’s a fairly simple technology, but by using gravity – and maybe a barrier of crushed round stone to help the water fall through – the French drain becomes a crucial part in keeping your basement dry. 

Usually, a French drain is made using a PVC pipe with holes drilled into it to allow water to filter in. A good one will be installed on a gradient, about one inch every 6-8 feet in the direction of an adequate place to drain. Adequate places to direct the water include out into the street near a storm drain, a ditch, a dry well, or any sloped part of your property where the water will drain away from the home. 


Why Do I Want A French Drain System?

You’ll most likely find a French drain at the foot of your foundation walls, as the Ontario Building Code has made them mandatory parts of a building unless they are proven to be unnecessary. But they can also be excellent solutions to standing water and other drainage issues you might encounter on your property. These are sometimes called shallow French drains or curtain drains, and they will run across your property to intercept water and channel it around a low point.

 If your lawn or driveway is perpetually waterlogged, for instance, a properly-installed French drain can direct the pooling water away from these areas. They can be used at the bottom of retaining walls to help relieve the pressure from moisture build-up, too. To prevent roots from growing into the pipe and ruining it, the drain can be switched to solid pipe as it passes an area with trees or bushes.

French drains can also be installed in the interior of your home. In this case, the French drain would be a trench installed on the inside of the basement wall that would catch water seeping inside and channelling it to your home’s sump pump. This would require the waterproofer cutting  a channel into the perimeter of the basement slab and installing perforated drain pipe directed to the sump pump well. They would then fill the trench with loose stone or gravel and smooth it over with concrete. It’s a solution more suited to unfinished basements, and even then it can be messy as they cut into the concrete. A drainage expert should be able to determine when it’s necessary!