Residential

Waterproofing and French drain installation

Problem

Building degradation due to excessive moisture and water seepage in the basement

Symptoms

  • Presence of a white powder on the concrete (efflorescence)
  • Presence of mildew at the bottom of the walls in the basement
  • Presence of water or damp concrete on the basement floor
  • Persistent humidity and odors

Causes

During heavy rains or snowmelt, the water pressure on the foundation causes the infiltration of water or absorption of water by concrete. This problem is caused by:

  • Deficient drain - Drains that have been installed for more than 25 years are often blocked by sand or fine soil particulate accumulated over the years. Whether the drain is made of plastic or baked clay, it could also be broken, displaced or crushed, resulting in its malfunction.
  • Presence of iron ochre - In this case, the gelatinous rust-coloured mud adheres around the drain and prevents water from evacuating thereby causing water infiltration. This problem is often combined with the water table being too high in comparison to the basement level.
  • Lack of drainage - In buildings constructed before 1950, we often notice that there is a lack of a drain around the footing. In such cases, if it rains for too long or too heavily, or when the snow melts, hydrostatic pressure can build up on the foundation and cause problems by having water leaks and damaged concrete.

Solution

Waterproofing of the foundation and soil drainage.

Work to be performed

  1. Excavation near the foundation using the appropriate equipment to cause less damage to property.
  2. Cleaning and waterproofing of foundations with an elastomeric membrane without joints, sprayed under the ground level.
  3. Soil drainage by perforated drain (French) at the base of the foundation and covered with crushed stone.
  4. Vertical drainage and protection of the membrane by a drainage panel under ground level. (Optional according to soil type).
  5. Basin for iron ochre. In that case, the drainage is unnecessary. The only guaranteed solution is to install a waterproof membrane under the concrete floor dating back to the exterior of the foundation to create a waterproof case to water. To perform required work, the uprising of the residence is often required.

Picture description

The pictures on the right provide a summary of the different steps involved in the process of waterproofing and installing a French drain. On the first picture: excavation work near the foundation. On the second picture: foundation cleaning. After these steps are accomplished, all cracks are repaired, as seen on the third picture. The fourth picture captures the application of a liquid membrane to the foundation. As for the fifth picture, it shows the backfilling of the French drain. Finally, the sixth picture shows the stone filling.