Buildings are compartmentalised to delay the spread of fire from one area to another. These compartments are usually linked by fire doors to allow the flow of traffic around the building. Fire doors have two important functions in a fire; when closed they form a barrier to shop the spread of fire and when opened they provide a means of escape.
A well designed timber fire door will delay the spread of fire and smoke without causing too much hindrance to the movement of people and goods.
Every fire door is therefore required to act as a barrier to passage of smoke and/or fire to varying degrees depending upon its location in a building and the fire hazards associated with that building.