Foundation water drainage systems rely on two fundamental principles:
Keep rain water away from the foundation wall perimeter
Drain groundwater with sub-grade perimeter footing drains before it gets to the foundation wall
Water drainage foundation systems are different from waterproofing systems. Waterproofing relies on creating a watertight barrier without holes or other means for water to enter. It can’t be done with concrete. Even boats need pumps or a place for water to run. Water drainage foundation systems prevent the build-up of water against foundation walls, thereby eliminating hydrostatic pressure. No pressure, no force to push water through a hole or crack. Remember, we know concrete walls will have holes or cracks.Mixing control joints with water management is a fundamental requirement for functional foundation systems that provide an extended useful service life.
Damp proofing should not be confused with waterproofing. Damp proofing protects foundation materials from absorbing ground moisture by capillarity (like a wick). Damp proofing is not intended to resist groundwater forces (hydrostatic pressure). If water management is used, 100% waterproofing is not necessary. However, control of capillary water is still required (dampproofing). Damp proofing is typically provided by coating the exterior of a concrete foundation wall with a tar or bituminous paint or coating.Draining groundwater away from foundation wall perimeters is typically done with free-draining backfill such as sand, gravel or drainage boards with drainage properties. At the base of the foundation a footing drain will carry away the water either to daylight or a sump pump. It is a fairly simple process of directing water to a piping system that will carry the water away from where it can do damage.Remember, step 1 is to guide rain water away from the foundation. Step 2 is to drain the ground water to a collection point so that it can be safely removed.