Nonmetallic ducts must be constructed with which classes of duct material?

Nonmetallic ducts are commonly required to be constructed with materials that meet specific fire performance criteria outlined in building codes. The correct answer indicates that Class 0 or Class I materials are suitable for nonmetallic ducts.

Class 0 materials have the highest level of fire resistance, meaning they do not contribute to the development of fire and have low flammability. Class I materials are also low-flame-spread materials but may allow for some degree of burning before extinguishing. These classifications are essential for ensuring safety in ventilation systems, as they help prevent the spread of fire through ductwork.

Using materials classified as Class 0 or Class I ensures compliance with safety regulations and minimizes fire hazards in buildings, especially in areas with high occupancy or significant fire risk.

Understanding the classifications helps in selecting the appropriate materials to meet safety standards while also achieving effective airflow in mechanical systems. The other classifications mentioned do not align with the necessary fire resistance standards for nonmetallic ducts.