Radon Mitigation Photo Album: Exterior System in Alpharetta

A concerned homeowner in Alpharetta, GA, requested a sub-slab depressurization system for his finished basement. He already had an energy recovery ventilator (ERV), but he also had air quality sensors throughout his house and was interested in getting his levels even lower.    The sensor in the mechanical room consistently had the highest level of radon in the basement. Though it was usually below 2.0 pCi/L, it was not a conditioned space, so the ERV did not reduce the level in that space as much as in other areas.    During our inspection, we noted that the garage floor was sitting on the foundation wall, and the crack between the two concrete sections was a likely entry point for radon. To address this, we designed a system with an extraction point through the basement floor in the mechanical room and another through the foundation wall to mitigate radon from below the garage as well.   Since the rest of the basement was finished, the system had to run high above the living space. In order to prevent any water traps from condensation during colder months, the fan was also located high on the back side of the home. Fortunately, it was not visible from the street or the adjacent properties.