A typical residential fire originates from food that has been left on the stove or has otherwise ignited. The flames immediately climb up the grease extraction duct. If the duct has not been insulated against fire in the attic space, the fire will spread to the attic with devastating consequences.  

Kitchen fan The duct of the local exhaust system must be insulated in the attic space and in the attic cavity. Please, check the local regulations.