In cases where an perimeter gap was purposefully left open by a previous waterproofing contractor to allow flood water that may be entering through the foundation walls a pathway into the drainage system, that opening presents a hazard for radon entry by providing a free-flow pathway for sub-slab gases to matriculate up into the living spaces which often causes a radon problem in homes that may not have had radon issues prior to adding the French Drain system. To effectively deal with these gaps, RMCA affixes a thick and sturdy vapor barrier over the crack that adheres to the foundation floor and walls upon applying heat to activate the adhesive side of the vapor barrier. We also install a “Green Drain”, shown in the graphic below to permit continued flow of flood water into the drain.
The Green Drain has a silicone flapper gasket that allows liquids to flow down into the perimeter drain while at the same time preventing radon from flowing up. By providing this pliable barrier to the drain opening, they increase our system efficiency by confining our suction to the high radon air underneath the slab. This prevents the radon system from removing conditioned air from the basement.
The vapor barrier may be crafted around existing built-in shelving in the basement