Why Radon Levels Increased After Encapsulating the Crawl Space and Sealing Vents

After encapsulating a crawl space and sealing outside vents, some homeowners report an unexpected rise in radon levels. This article explores the reasons for this phenomenon and offers recommendations to address the issue effectively.

Airflow Changes

Sealing the crawl space can significantly alter the airflow, leading to a decrease in natural ventilation. Radon typically migrates from the ground into the home through tiny cracks and openings. When airflow is reduced, radon can accumulate more easily within the space and even within the living areas of the home.

Pressure Differences

Encapsulation can create a negative pressure in the crawl space relative to the rest of the house. This pressure difference can draw radon gas from the soil into the living areas instead of allowing it to escape. The negative pressure within the crawl space can become a conduit for radon to enter the home, bypassing the intended barrier.

Soil Saturation

Altering the moisture levels in the crawl space through encapsulation can impact radon gas release from the soil. In some cases, increased moisture can lead to higher radon emissions. Moisture facilitates the movement of radon gas, potentially resulting in elevated radon levels.

Improper Installation

If the encapsulation was not done correctly, it might not effectively block radon from entering the home. Gaps or leaks in the encapsulation can allow radon to seep in, negating the intended benefits of sealing the space.

Seasonal Variations

Radon levels can fluctuate based on various factors including temperature, humidity, and atmospheric pressure. Changes in these factors after the encapsulation might have coincided with the observed increase in radon levels. Seasonal variations can create conditions favorable for radon accumulation.

Recommendations

Testing

Conducting a radon test is essential to verify the current radon levels in your home. Short-term tests provide immediate insights, while long-term tests offer a more accurate picture of your home's radon levels over time. This will help you understand if further action is necessary.

Ventilation

Improving ventilation in the crawl space can help reduce radon accumulation by allowing fresh air to circulate. Consider installing a system that brings in air yet reduces the loss of conditioned air. This can be achieved through an air-to-air heat exchanger, which exchanges the temperature of the indoor air with fresh air while still providing some ventilation.

Radon Mitigation System

If radon levels remain high after testing and ventilation improvements, it may be necessary to install a radon mitigation system. A typical system includes a fan and piping to safely vent radon gas outside the home. This approach ensures that radon does not accumulate inside the living areas.

Consult Professionals

Reach out to a radon mitigation specialist to assess your specific situation and provide tailored solutions based on your home's design and radon levels. Professionals can offer expert guidance and ensure that the encapsulation and radon mitigation measures are implemented correctly.

In summary, while encapsulating a crawl space and sealing outside vents can help reduce radon entry, it does not guarantee the elimination of radon. Understanding the reasons for the increase in radon levels and implementing appropriate solutions, such as testing, improving ventilation, or installing a radon mitigation system, can effectively manage and reduce radon levels in your home.