French drains are typically installed outside the perimeter of the footings at ground level. Their purpose is to minimize water infiltration beneath the footing or between the footing and the foundation. The drain is usually connected to a sump pit and can be wrapped in a membrane to reduce the risk of clogging by solids. However, the use of wrapped drains is now discouraged due to the tendency of the thin textile wrap to become easily clogged over time. The recommended approach is to cover the drain and the exterior of the footing with clean crushed stone to improve water flow towards the drain. A 30-inch wide geotextile membrane is then placed over the stone before backfilling to prevent soil contamination and maximize drainage performance.
In soils prone to iron ochre, a bacteria that tends to clog French drains, it is often advisable to replace flexible drains with rigid BNQ-type drains. This rigid drain is then covered with stone and topped with a geotextile membrane.
Our team is equipped to install most of the waterproof membranes available on the market. These membranes will be applied to the walls of your foundation to protect against water infiltration and potential cracks. For the best value in foundation protection, we recommend applying a layer of bitumen (tar) on your walls, followed by a delta-type membrane over the bitumen.
