Above what height must exhaust outlets located above the roof terminate above the roof surface?

Exhaust outlets located above the roof must terminate at a height that ensures effective dispersion of exhaust gases and prevents them from entering windows or other openings, particularly in neighboring buildings. The North Carolina Mechanical Code specifies that exhaust outlets should generally be positioned at a minimum height above the roof surface to create a safe margin for avoiding any potential hazards related to exhaust gases.

The requirement for a termination height of 40 inches effectively helps facilitate proper airflow and reduces the likelihood of exhaust re-entering a building. This height is designed to account for wind currents and other environmental factors that can influence how exhaust is dispersed. Ensuring that the outlets are at least this height helps maintain a balance between ventilation efficiency and safety, adhering to code requirements for mechanical systems.

In contrast, the other options present heights which may not sufficiently mitigate the risk of re-entrainment or might not comply with regulatory standards, potentially leading to unsafe conditions.