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French Drain - Jargon Busters

June 2, 2015

Jargon BustersWelcome back to a new feature on the website: Jargon Busters!

In a new series of articles we are going to look at some popular industry terms and let you know exactly what they mean.

Next up is the popular, but increasingly old fashioned, waterproofing technique: The French drain.

How do they drain water? Why are they French? Are they any good? Read on to find out...

Are French drains even French?

The French drain actually has no association with France at all. In fact, the inventor of the drains was a man from Concord, Massachusetts, USA, named Henry Flagg French.

What is a French drain

The French drain, created in the 1920s, is an old-school waterproofing system which helps manage the ground and surface water flow around a property, preventing it from penetrating building foundations.

A French drain is typically installed during the construction of a property - inbetween the property foundation being built and backfilled. In recent times French drains have been used to waterproof basements and cellar conversions.

How do French Drains work?

The French drain is buried around the perimeter of the property, usually under the property walls, and is covered in small crushed stones to prevent fine particles from passing. Fabric filters may also be used. The soil that was dug up is then back filled on top of the French drain.

The idea behind the drain is that any water that manages to reach down to the small crushed stones would be collected by the French drain (as opposed to entering your property). The water is then channelled away from the property and safely disposed.

French Drains have served properties well over the years but they are not without their flaws.

Potential issues

As you could probably imagine, the French drain eventually becomes clogged up through years of collecting sediment.

Typically, French drains can operate for up to 10 years before developing any issues, but it really depends on the site conditions and how well the pipe was initially installed.

Eventually, the French drain will need servicing and this can be a really messy and expensive process.

Repairing french drains

To access the French drain, a trench would need to be dug around the perimeter of the property.

Unfortunately, any landscaping located close to your property may also need to be removed. This is when it can get really messy and expensive. Walkways, garden beds, steps, shrubbery, porches, patios and decks may all be affected.

Even after replacement, if the same system is put into place, so in a decade or so the whole process may need to be repeated.

Alternative solution - Install an interior drainage

A much more modern, reliable, maintainable and cost effective solution to waterproofing your cellar or basement would be an internal waterproofing solution.