Fire doors are needed to prevent the spread of flames and provide an escape for people inside the building. There are strict guidelines in the U.K. governing the design of fire doors. All doors have to be certified for use by a testing centre before they are released for purchase. This guarantees they will resist a fire for a specific length of time and prevent smoke from spreading.
Fire doors are required for all doors that lead to staircases from corridors and rooms as well as for doors between basements and upper floors. Doors that lead to kitchens, laboratories, store rooms, plant rooms should also be fire doors.
All fire doors should be fitted with intumescent strips (strips that expand at 100 degrees to fill gaps) and doors that lead to stair enclosures or protected corridors must have smoke seals.
All fire doors should open in the direction of escape and should not swing both ways (double swing), otherwise smoke seals will not work correctly. An exception to this is mid-corridor doors that act as smoke breakers.
All doors should fit closely to the frame, with a maximum gap of 5mm. The doors should be hung with at least 1 1/2 pairs of all metal hinges, which have minimum melting point of 800 degrees Celsius. Nylon hinges are not appropriate. Doors must have a self-closing device. This must be able to beat the resistance of locks and latches in order to close the door tightly against the door stop.
Fire Resistance Time
Different fire doors are certified with different time periods of fire resistance. At a minimum, doors must resist a fire for 30 minutes without cracking or opening enough to allow flames or hot gases to pass through the door. However, some doors are built to resist fire for 60, 90 or 120 minutes.
The door frame should be compatible with the door. In general, for "FD30" doors, the frame must be at least 30mm thick and for "FD60" doors, the door frame must be at least 60mm thick. Steel door frames should not be used. Gaps between the wall and the back of the frame should be filled with intumescent paste, plaster or mineral wool. The same type of intumescent material must be used throughout the door frame.