What is the requirement for the ceiling height in corridors to function as a return air plenum?

In the context of the North Carolina Mechanical Code, the specific requirement regarding corridors functioning as return air plenums is that they are not required to be constructed with fire-resistance-rating materials. This is significant because it allows design flexibility in building corridors that serve multiple functions, including acting as return air plenums for HVAC systems.

Return air plenums are air spaces that facilitate the circulation of airflow back to the air handling unit. By not mandating fire-resistance-rated construction for corridors used as return plenums, the code acknowledges that these spaces can be integrated into the overall building design without the added complexity or cost associated with fire-resistant materials. It’s important, however, for designers to ensure that other safety and ventilation aspects are still maintained.

While the other requirements such as ceiling height of 7 feet or restrictions on enclosure may be relevant to various building codes, they do not specifically address the unique characteristics and requirements for corridors designated as return air plenums. Therefore, the option correctly identifies a unique aspect of the code that facilitates practical building design while ensuring that basic safety standards are met.