In general, ductwork may pass through compartment walls or floors which have a prescribed fire resistance period in terms of load-bearing capacity (stability), integrity and insulation criteria.
It is critical for the ductwork to have at minimum the same performance of the fire rated walls or ceilings. This is to ensure that compartmentation of the area is not compromised as fire can pass through an unprotected duct. Furthermore, the selection of suitable ductwork system can be relatively more complicated when because it passes through different fire compartments and the relevance of the system’s function in ambient as well as fire conditions. Typical ducts can be used as smoke extract system, ventilation system, air conditioning ducts, kitchen exhaust system and pressurization duct. Fire rated ductwork can be constructed of metal but shall be protected with fire resistant intumerscent coating or boxed up with fire resistant boards to appropriate rating test by recognized laboratory. Alternatively, they can be constructed out of fire rated boards to form a proper fire rated duckwork provided it has no leakage so that negative pressure can be maintained during smoke extract process.