Find out all there is to know about French drains and be an informed owner with the help of Bisson Expert!

As an owner, being familiar with the various components of your house gives you an advantage towards protecting your investment, ensuring the proper maintenance of your building and avoiding problems. In fact, you are thus in a position to thoroughly understand the purpose of each building element and to recognize the early warning signs of an unsafe situation. A French drain is an integral part of the components that play a key role in a building, but are however not well known to the general public. This is why Bisson Expert can tell you all there is to know about French drains. Being a well-informed owner always pays off !

What role does the French drain play in a house ?

The French drain is a drainage system that protects your foundation against humidity and water infiltration. For example, when the soil around your house is saturated with water, hydrostatic pressure builds up on the foundation, especially during climate changes. The concrete may start to crumble or water infiltration may occur and cause damage to the property. The purpose of the French drain is to lower the pressure by facilitating water drainage. It helps to keep the bottom part of the foundation dry and avoid moisture-related problems.

It is therefore important to know that the purpose of the French drain is to capture and drain the water that accumulates around the foundation footing. In addition to collecting excess surface water in case of soil saturation, it also controls the groundwater that we can’t see and that varies (underground stream, unconfined groundwater).

This is why it is installed near the foundation footing during construction.

Are all houses equipped with a French drain?

In the province of Quebec, all residential houses built since 1955 must be equipped with a French drain, which means that most houses today are equipped with this type of drain. If you own a recently built house, you probably think that you are protected from moisture problems. Think again. Even a new house can be affected by several factors that can deteriorate the French drain or impair its efficiency.

If you live in an old house, it is quite possible that a French drain was never installed. If you are not sure, a foundation expert can help you get a better picture.

Keep in mind though that the absence of a French drain does not automatically create excessive moisture problems. In many regions, houses are not equipped with a French drain and excessive humidity or moisture-related problems remain relatively rare. This is due to certain environmental factors, such as urban planning, ground level or soil composition, that can help keep the foundation dry. Check with your local municipality to find out what the rules, regulations and environmental conditions are to ensure compliance of your property.

What factors can have an impact on the efficiency of your French drain ?

As mentioned, whether your house has been recently built or not, several factors can have an impact on the performance of your French drain, including the following.

A clogged French drain
It is not unusual to see the accumulation of particles in a French drain. These mineral, grain and dust particles come from the soil and water surrounding the drain. A large quantity of particles can clog the drainage system even after only a few years. It goes without saying that a clogged French drain does not work properly. Fortunately, drain installation has improved with today’s building methods and several steps can now be taken to better protect a new drain. Layering at least 12 inches of crushed stones over the drain and adding a geotextile membrane will filter all the soil particles and prevent them from getting into the French drain.

An incorrectly installed French drain
Unfortunately, some builders do not quite master the art of installing a French drain. It is not unusual to see a new drainage system that is either incorrectly installed or covered with an insufficient quantity of crushed rocks. In case of doubt, a drain test with camera can reveal if the levels are correct or if some parts of the drain are crushed or twisted. Sometimes, the drain is simply not installed at the right depth. The joints where the footing and foundation wall meet are more likely to let water through, which in turn will accumulate in the drain. The joints where the interior concrete walls and floors meet will be damp and even very wet during heavy rainfall.

The French drain is at the end of its life cycle
It is also important to note that French drains have a finite life cycle based on their components and environmental conditions, as with all other building materials. Reinstalling a French drain is part of the property’s maintenance cycle. For example, most terracotta drains installed in the 1950s and 1960s are deteriorated and must be replaced. On the other hand, if the soil is sandy or if there is a lot of vegetation, the life cycle of the French drain could be shorter. In areas where iron ochre is present in the soil, the iron particles in the soil will rapidly clog the drainage system, which will need to be equipped with shafts to allow for regular cleaning. In areas where buildings are all the same, the neighbourhood is a good source of information because conditions are often similar. If your neighbours are redoing their French drain, you may want to think about it too !

What is the life cycle of a French drain ?

Generally speaking, a French drain will last approximately 30 to 40 years. However, the above-mentioned factors may shorten its life cycle and it must then be replaced by a team of foundation experts.

What should you do when you suspect a problem with the French drain ?

If you think that there is an excessive level of humidity in your house or if you notice water infiltration, your French drain may well be the culprit. You must remedy the situation as soon as possible because moisture can cause structural problems in your house and even be bad for your health. Experts can help find the source of the problem. At Bisson Expert, we recommend a preventive inspection using a camera to find out the actual condition of your French drain.
For more information on excessive moisture and warning signs, read this article.

When should you install a new French drain ?

If you think that your French drain must be replaced and wish to get a quote, contact a foundation expert. Prices vary depending on the size of your house, the constraints regarding access to the foundation and the scope of the work to be carried out to replace the French drain. Rest assured however that a new French drain should be seen as an investment in your property since it will keep your house in good condition !

Furthermore, carefully chose the professionals who will install your French drain. At Bisson Expert, we have been doing foundation work for more than 50 years and we resort to the best available methods when installing a French drain. This is important because, after all, your French drain will play a key role in waterproofing your house and foundation !

Whatever the case, don’t wait any longer to have your French drain inspected or to have one installed if your foundation is at risk: remember that prevention is better than cure !

For more information on French drains, click here.

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