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How to install French drain?

The French drain system and all its trenches are nicknamed “the highway”, since it intercepts water all around the foundation in order to direct it to an exit point. This point will use gravity or be forced using a pump to raise the water, which will allow its evacuation.

It allows your basement to stay dry by directing groundwater before it penetrates the concrete slab. In the event that groundwater seeps into your home, there are many chances of seeing mold appear, in addition to seriously damaging materials or property. Also, it is important to mention that repeated water infiltration significantly contaminates the air due to the proliferation of fungi, causing mold. You should know that anything that can putrefy (rot) will be affected, since the material is still alive. Only inert materials, for example styrofoam, concrete or a vapor barrier will be spared. In reality, as there is a good chance that dust covers these materials, they will also be contaminated.

A property that does not have a French drain risks the damage mentioned above, but can also have a serious impact on the health of the occupants. Molds that develop as a result of prolonged exposure to humidity affect the quality of the ambient air, thus increasing the risk of lung diseases, for example.

Remember that a mushroom needs 3 elements to live: water, air and putrescible material. If you remove any of these, the fungus will not die, but will become more or less inactive. As soon as the 3 elements are reunited again, it will reactivate. This is why a very methodical work must be carried out during the elimination (demolition) of the contaminated materials towards the exterior of the property. Mushrooms are very volatile, their spores move like the pollen of a flower. As soon as they are shaken, they spread all over the air and sometimes even go up to the upper floors. Imagine, if in addition you have a forced air heating system that works at the time of demolition! Your safety and that of your family could be seriously affected. That’s why you should trust an experienced team like Groupe Durasec.

Dommage eau sous-sol

This is one of the many reasons why the building code now requires all new constructions to have a French drain.  
The best way to mitigate these risks is to install a French drain and maintain it regularly. But how do you install a French drain?

What are the installation costs? 

Purchasing and installing a French drain represents a significant expense, but it is a guarantee of safety as well as an investment for your home during snowmelt or heavy rainfall. 

Based on many factors such as the portion of the foundation that is in the ground, the length of the drain to be installed as well as the severity of the work and obstacles, the installation price will be around $20,000, sometimes more. 

Since no house is built the same depth in the earth as another, it is often foolish to get a price according to a calculation that was based on linear feet. The prices that our experts quote include the excavation, the waterproofing of the foundations as well as the installation of the French drain, based on the actual dimensions of your residence.

What will be the lifespan of the French drain?

Although it is necessary to maintain your French drain throughout its useful life, it is usually estimated that the life of the drain stretches up to 25 years, depending on the type of soil around it. Thanks to the choice of an effective membrane such as RUB-R-WALL for the waterproofing of your foundations , we wish to extend the life of the French drain up to 100 years, duly tested in the laboratory according to the DURASEC standard.

In order for the drain to fulfill its primary function in the most optimal manner possible, Groupe Durasec can carry out its maintenance on a periodic basis. First, we will perform a camera inspection to determine if things such as roots, mud or other residue are clogging the drain. Afterwards, we can proceed to clean the drain. Note that this maintenance work will have to be repeated every few years.

If we notice that it is at the end of its life, we will let you know and take the time to explain the rest to you, allowing you to start thinking about replacing the French drain.

Installing a French drain

The positioning of the French drain is the key to success in the installation process! The concrete slab being the place where there must absolutely not be a drop of water, it is essential to install the drain in such a way as to intercept the water before it enters the basement. To fully understand what a French drain is for and what happens under your house when the water table rises, you have to imagine that a lake is buried under your house and that when the snow melts or it rains, the lake level rises.

The second element to plan is the installation of the drainage system.  It is necessary to choose the location of the collection tank according to where the rain outlet will be located during construction, in the case of a new construction for example. Subsequently, the location of the manholes will be determined. The number of chimneys will be chosen depending on the design of the foundation. 

Before installing a new French drain, it is essential to use the right materials. Thus, it will be necessary to use smooth drainage pipes according to the BNQ standard (without grooves) perforated with a diameter of 4’’. This will allow water to enter through the openings provided for this purpose, and this, over the entire length of the pipe.

It is preferable to choose pipes that have ½ inch round holes, rather than small slots since they allow more water from the groundwater to enter. In addition, when cleaning is necessary, the technician can more easily dislodge fine particles from the ground or iron ocher deposits. This greatly prevents the risk of blocking.

Finally, in order to carry out the work in the most optimal way while enhancing the protection offered by the French drain, a filtering geotextile fabric as well as a large quantity of ¾ net gravel will be necessary.

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