EXTERIOR FRENCH DRAINS
Exterior drain tiles or "French drains" around the area of the foundation footing serve as the first line of defence against groundwater. To deal with any water infiltration problem, using these drains along with the combination of proper membranes is an ideal solution. Call Akton Injection to install exterior French drains in Montréal, which is one of the best ways of basement waterproofing.
A “French drain” is an ancient technique in which a ditch is excavated around a building which is then filled with gravel, as a means to redirect surface and groundwater away from penetrating or damaging building foundations. The actual term was taken from Henry F. French who promoted the drainage technique in the mid-1800s in a book called “Farm Drainage”. In reality, the French name “Drains Francais” is a misnomer because it should be called a “Drain French”.
The most common causes of basement water infiltration are unmanaged rain runoff and high water tables. Rainwater from the roof flows down through the soil and collects at the bottom of the original foundation excavation. While the weight of the saturated earth alone can break a wall, the situation worsens when the water freezes and exerts a lateral force that can cause cracks and buckling.
Exterior French Drain Installation
The question is how to build a French drain? To create a French drainage system, we will first excavate around the perimeter of the building all the way to the footing of the foundation.
First, our team will wash the foundation and inspect it for cracks and imperfections. Then, we will fill all the large cracks with injections and resurface the imperfections with a hydraulic cement for a smooth surface to apply the membranes. Once this product has cured, a protective coating of the elastomeric membrane is sprayed on the foundation which creates an impenetrable rubber barrier. This will cut all the humidity entering into the concrete and help to prevent future deterioration. Once the elastomeric membrane has cured, a dimpled plastic membrane called Delta®-MS fully seals the foundation. This membrane will relieve the pressure of the earth off the wall creating drainage and protects the rubber membrane from damages during the backfill.
We then lay out weeping tile (perforated plastic pipe) around the building, coated with a geotextile over it, which is used to prevent the migration of the drainage material as well as preventing dirt and roots from entering and clogging the drainage pipe. Once the French drain is installed, we’ll cover it with 2 feet of 3/4 inch clean gravel. Finally, the gravel is covered with earth all the way to the previous ground level. In this way, a 4” French drain can be installed.
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Exterior French Drains
The step-by-step process of installing exterior French drain is:
Step 1: Excavate down to the footing around the perimeter.
Step 2: Scrape and wire-brush the wall clean.
Step 3: Clean the wall with a pressure washer to remove all loose material.
Step 4: Seal cracks with an injection if necessary and fill in all joints with hydraulic cement for a smooth surface to apply membrane.
Step 5: Apply elastomeric membrane (Cantex coating/rubberized membrane).
Step 6: Apply the wall drain and protection board (Delta®-MS).
Step 7: Lay down the French drain (weeping tile) wrapped with a geotextile protection cloth.
Step 8: Connect French drain to an existing drain or create sump pump pit.
Step 9: Connect window well and cleanout pipes.
Step 10: Cover French drain with 24" of 3/4 clean gravel for maximum drainage and filtration.
Step 11: Backfill and grade the earth around the perimeter.
Step 12: Remove all excess earth and clean the work area.
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