Under what condition can the ASD discharge point be below the roof?

The condition that allows the Air Silencer Discharge (ASD) point to be below the roof is rooted in practicality and safety considerations. If it is not possible to comply with above-roof requirements, it indicates that there are either structural limitations, design constraints, or site-specific challenges that prevent the vent from being positioned above the roofline.

In such scenarios, local and state codes may provide specific guidance or exceptions based on the circumstances. The main goal is to ensure that the discharge point does not cause a backdraft of radon or other gases into living spaces, which typically necessitates higher discharge above the roof.

Options such as governing local codes or the height of the building do play significant roles in compliance; however, these factors must always be considered within the broader context of safety and feasibility in mitigation efforts. If structural constraints make it impossible to meet standard requirements, then using alternative methods to ensure effective radon mitigation while still protecting indoor air quality is crucial.