What is the minimum height requirement for the exhaust if below roof level?

The minimum height requirement for the exhaust when positioned below roof level is typically set to ensure that radon and other harmful gases are adequately dispersed into the atmosphere, minimizing their potential re-entry into living spaces. A height of not less than 10 feet above grade is sufficient to achieve this, allowing for effective ventilation and dilution of the exhaust emissions in the outdoor air.

This height is designed to prevent potential inhalation exposure and to comply with safety standards aimed at protecting occupants within the building. Ensuring that exhaust systems meet this minimum can significantly reduce health risks associated with radon exposure, which is why it is an important guideline in radon mitigation practices.

In comparison, other height requirements that exceed 10 feet, such as 15 feet or 20 feet, might provide additional safety in certain contexts, but the specific standard of 10 feet is recognized as the minimum that strikes a balance between safety and practicality in most scenarios.