What should be the condition of the house during post-mitigation radon testing?

For post-mitigation radon testing, the house should be in a closed condition. This is crucial because having the house closed minimizes the impact of outside air on the radon levels being measured. A closed condition typically means that all windows and exterior doors should be closed for at least 12 hours prior to testing, while also maintaining a normal living condition inside the house (e.g., using the heating and cooling systems as needed).

By keeping the house closed, the testing process ensures that the results obtained reflect the effectiveness of the mitigation system in reducing radon levels, rather than fluctuations caused by external factors or ventilation changes. Therefore, a closed house provides a stable environment that showcases the performance of the mitigation efforts.