Fire Rated Ducting Iraq usually needs to pass through compartment walls or floors that will have a prescribed fire resistance period in terms of the load-bearing capacity, integrity and insulation criteria, for durations of 30 to 240 minutes. It is a requirement that where these compartment walls/floors are penetrated by HVAC ducts or other building services, the fire performance criteria for the penetrated wall or floor are maintained, such that fire in one compartment may not spread to other areas.