A foundation drain refers to a kind of exterior drainage systems that are usually installed around the external face of a foundation close to a wall footing. It is usually covered with some gravel and drains any excess water that finds its way to the foundation.
The most important part of the foundation drain usually is a kind of perforated pipe that is laid around the entire perimeter during foundation drain installation. It serves the purpose of capturing any surplus water and draining it to the direction of a storm sewer, soak pit, or catch basin that is a bit far from the structure itself. It is designed in such a way that perforations are in the form of thousands of small holes, slits in some cases, which act as an entrance for the surplus water to find its way into the pipe for after which it is drained to the storm sewer or soak pit and away from a foundation. Usually, the pipe gets covered with some form of permeable sock that prevents soil from making its way into the pipe. After the mesh, a layer of gravel that comes in graduated sizes is added followed by soil which is used to backfill. The main reason for using gravel is to make it easy for water to flow to the perforated pipe. A porous pipe, also known as the weeping tile, is usually installed sloping in the opposite direction of the walls of the structure and delivers water to the sewer system.
Several things need to be considered when it comes to the design of foundation drains to make sure that the water is drained effectively. First, anyone constructing any type of foundation drain needs to make sure that they meet the residential code. It requires any drains constructed around masonry or concrete foundations to have the capability of retaining earth and enclosing usable or habitable space below grade. Soils with extremely good drainage are however exempted especially when it comes to gravel and sand mixtures that do not need drainage. Drainage boards on the other hand are common in places that regularly experience heavy rains. They are used as a drainage channel for any water fast to a perimeter drain. To do this, they are usually installed on the wall of the concrete foundation. The foundation drainage installation is aimed at preventing hydrostatic pressure from building up close to the walls. Any perimeter drain should be constructed using a perforated pipe or robust drain tile. While corrugated pipes made of plastic may be used, a lot of care is needed to make sure that it is not crushed during the backfilling process. The moisture in the soil close to the foundation can significantly impact the drainage of water from footing since the moisture depends hugely on the soil type placed around. Drain pipes need to be placed alongside footing, preferably close to its base.
Foundation drains are available in different types including the French drain which utilizes perforated pipes placed next to the structure of the foundation wall. The perforated pipe is positioned sloping in a direction opposite to the structure after which a porous material like gravel is used for backfilling to ensure that water standing on the surface flows easily to the pipe for draining. Another type of foundation drain is the footing drain which is one of the most effective foundation drainage installation systems. This one involves the installation of a pipe around the walls of a foundation. The pipe is meant to collect any excess water that may have leaked via the footing of the basement after which it is drained from the walls. Usually, gravel is used to cover the drain to the surface of the soil.
