Hollow block masonry foundation walls must be constructed with either a continuous course of solid masonry, one course of masonry grouted solid, or a solid concrete beam at or above finished ground surface to prevent passage of air from the interior of the wall into the living space.
Blocking Potential Entry Routes
Drains, floor openings, etc.
Potential radon entry routes: Floor openings around bathtubs, showers, water closets, pipes, wires, or other objects that penetrate concrete slabs or other floor assemblies should be filled with a polyurethane caulk or equivalent sealant applied in accordance with the manufacturer’s recommendations.
Condensate drains should be trapped or routed through non-perforated pipe to daylight.
Joints, Foundation cracks, etc.
All concrete control joints, isolation joints, construction joints, and any other joints in concrete slabs or between slabs and foundation walls should be sealed with a caulk or sealant.
Gaps and joints should be cleared of loose material and filled with polyurethane caulk or other elastomeric sealant applied in accordance with the manufacturer’s recommendations.