Dampproofing
A simple dampproof coating is sufficient where positive drainage is reliable, the seasonal water table never rises above the footing, or the basement is not living space.
Dampproofing Concrete Block Basements
Spray-applied waterproofing and some waterproofing membranes can be applied directly to concrete block. However, dampproofing should be applied over parging.
Parging Concrete Block
Before parging walls, brush off any dirt and dampen wall with a water spray (do not soak).
To parge walls, trowel on two coats of Type M or S mortar. Each coat should be at least 1/4 in. thick, for a total minimum thickness of 1/2 in. Roughen the first coat with a brush when the wall is partially dry to ensure good bonding.
Allow the first coat to harden for 24 hours before applying the second coat. Cure the topcoat for 48 hours before applying dampproofing.
Form the parging into a cove where the wall meets the footing to direct water away from the joint (below).
Waterproofing
Apply waterproofing products in the following situations: When soils are slow draining; basement walls are below the water table; drainage is unreliable; or the basement encloses habitable space (below).
Drainage Panels
Some waterproofing systems employ a dimpled or expanded-fiber geomat fastened against the foundation, either with or without an additional coating material applied to the foundation wall. These drainage panels provide an immediate break in hydrostatic pressure, carrying water from the backfill into the perimeter drains.