French drains 101

Does your lawn get soggy when it rains? Is your basement flooding during downpours? Perhaps you’re building a new home. If any of these apply, you may want to consider a French drain.

Simply put, a French drain is a drainage system that uses natural slopes to divert water away from a structure, such as the foundation of your home. First developed by farmer Henry French in the mid-1800s, it usually consists of gravel, perforated pipe, and, in some cases, a sump pump. But, whether or not you have a French drain, you should ensure that footing drains will direct water away from the foundation.

The type of French drain you install depends on the problem you’re trying to solve or avoid. As with any important home improvement, you may want to consult a professional.


Standing water

To fix a soggy lawn, a curtain drain installed directly uphill from the problem area is your best bet. Simply:

  • dig a shallow trench on a downhill course in the direction you want to divert the water,
  • lay down perforated pipe, and
  • fill the trench with loose gravel.

Travelling water seeks the path of least resistance and aided by the loose gravel, will seep into the pipe and continue on its new path. If the trench must pass through an area with shrubs or trees, use non-perforated pipe for those sections to keep out roots and guard against pipe damage.


Basement flooding

A wet basement is a serious issue that can have a catastrophic impact on the safety and value of your home. There are two types of French drains that can help with this issue: exterior and interior.

An exterior French drain is installed by digging a deep trench all the way around the perimeter of the home, down to the footing. Perforated pipe is laid and, in most cases, a sump pump is required to pump the water out as it accumulates. This type of installation is best completed when the home as being built as demolishing walkways, staircases and decks around the perimeter of a home can get expensive.

An interior French drain is installed by cutting into the basement walls from the inside, so perforated pipes can catch the water as it enters the basement, diverting it to a collection tank, where is expelled by a sump pump.

Whatever the type of French drain you install, it is recommended to opt for a sump pump with a battery backup that will automatically begin pumping during power outages.


Inspection and maintenance

It’s easy to overlook a French drain when doing your annual home inspection. However, if you have a below ground French drain, it’s best to check it regularly for debris and clogs.

Clear debris from the drain exit as it accumulates to minimize the chances of back up. Use an electric sewer snake to clear clogs inside the drain pipes, then flush with a garden hose. A pipe inspection camera is a handy tool for checking out any tougher clogs or pipe damage. If the latter occurs, consult a professional before attempting repairs. If your drain system includes a sump pump, make sure to inspect that as well.




Groupe Durasec

CAA Quebec



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