How far above a pitched roof should the exhaust extend?

The correct answer indicates that the exhaust must extend not less than 1 foot above a pitched roof. This requirement is important for ensuring that the exhaust gases from the ventilation system are properly released into the atmosphere without causing issues such as backdraft or re-entry into the living space. By extending the exhaust at least 1 foot above the roof, it mitigates the risk of the gases being drawn back into the home and helps to promote adequate dispersal, which is crucial for both safety and efficiency of the system.

The guideline is based on standards that consider factors such as wind direction, roof slope, and potential obstructions that could cause turbulence. A distance of 1 foot above the roof ensures that the exhaust is above most of these obstacles, contributing to better performance of the ventilation system and adherence to safety regulations.

Other options suggest varying heights that do not align with the requirements set by standards such as those established by the National Fire Protection Association (NFPA) or other building codes. For instance, while extending the exhaust 2 feet or 5 feet might provide an extra safety margin, they are not the minimum requirement, which is what is being specified in the question.