Background
Radon gas is a colorless, odorless, and tasteless radioactive gas that emanates from the natural decay of uranium found in soil and rock. Prolonged exposure to high levels of radon can pose significant health risks, including lung cancer. This case study examines a radon mitigation project undertaken in an early 1900s home, which was found to contain levels of radon gas significantly higher than the Environmental Protection Agency (EPA) recommended action level of 4.0 pCi/L.
Problem Identification
The homeowner, motivated by health concerns related to radon exposure, opted to have their property tested for radon gas. The results showed alarmingly high levels exceeding 27.0 pCi/L. Given the potential health hazards associated with prolonged exposure to such levels, immediate action was necessary to mitigate the risks.
Property Assessment
Upon inspecting the property, several factors were identified that contributed to the elevated radon levels:
- Foundation Structure: The home was built on a rubblestone foundation with brick flooring in the basement—conditions that are known to facilitate radon seepage.
- Partitioning: The basement was segmented into three separate rooms by foundational walls, along with two additions constructed on crawl spaces, creating an environment conducive to radon infiltration.
- Ventilation Limitations: Traditional radon mitigation systems that involve venting air through concrete floors were not applicable due to the presence of brick, which complicated the mitigation strategy.
Mitigation Strategy
Following the property assessment, a customized radon mitigation system was designed to address the unique challenges presented by the home’s structure:
- System Design: A sub-membrane depressurization system was chosen due to the impracticality of conventional basement system designs. A 15 mil vapor barrier was installed on top of the brick flooring, accompanied by 40-50 feet of perforated pipe beneath the membrane.
- Wall Sealing: Given the rubblestone foundation, directly sealing the vapor barrier to the walls was not feasible. Instead, expanding foam insulation was utilized to ensure an airtight seal.
- Crawl Space Integration: The air collected from the basement sub-membrane was routed into the crawl space, which was also sealed with 15 mil poly. This air was then directed to the garage, where a fan was installed in the attic to vent it through the roof.
Implementation
After the homeowner approved the proposed mitigation design, a four-member crew executed the installation in less than a day. The effort was completed efficiently, aiming to minimize inconvenience to the homeowner.
Results
The success of the mitigation system was quickly evidenced by the homeowner’s radon monitor, which displayed a significant reduction in radon levels within hours of installation. A post-mitigation test confirmed that the radon levels had decreased to a safe 1.1 pCi/L—well below the EPA recommended action level.
Conclusion
The homeowner expressed immense relief upon learning that their home no longer posed a health risk due to elevated radon levels. The successful installation of the radon mitigation system not only offered peace of mind but also ensured a safer living environment for the family.
This case underscores the critical importance of testing for radon and taking proactive measures to mitigate its risks. Early detection and intervention significantly enhance the likelihood of protecting the health of those residing in the home. Through this experience, the homeowner was particularly grateful for the swift and effective response to their radon concerns, reinforcing the value of awareness and preventive action regarding indoor air quality.
