The prime purpose for fire doors is to save lives and stop the progress of fire in support of both escaping occupants and fire-fighting activities. They are an important part of a building's passive fire protection system and an essential requirement for the vast majority of premises including residential, public buildings, offices and factories (specific building regulations must be checked).
The main functions of fire doors are:
To allow egress from a space and to close once released
Protect escape routes from the effects of fire (smoke, gases and flames)
Potentially limit the amount of oxygen available and slow the growth of a fire
Fire doors are manufactured to withstand the spread of fire for a given period, normally a minimum of 30 minutes. This allows time for people to leave the building via an escape route if other routes are impacted by the effects of fire.
Fire doors are an engineered component which includes the frame, door leaf and any fixtures and fittings. They can be solid or made with a special core, often flax board or a wood composite material. They will be fitted with intumescent seals, installed in the frame or leaf, which seal the door on impact with heat to stop the spread of fire and/or smoke around the edges of the door. Doors will similarly be fitted with smoke seals to prevent the passage of smoke in the early stages of a fire.
Fire-rated doors must be installed correctly in accordance with the manufacturer's instruction and include the specified ironmongery and other facilities which represent the doorset as originally tested as this is critical to the door's performance in the event of a fire. The British Woodworking Federation believes "third party certification is the only way to ensure that Fire Doors are manufactured consistently to protect lives and save property. Cutting corners can cost lives."
Fire doors can be made with a combination of timber, steel, gypsum, and aluminum, and the most widdely used ones are Steel Fire Door and Wood Fire Door. They can also have windows, which are made from borosilicate or ceramic glass (both of which offer a higher fire resistance than standard glass), and may contain an anti-shattering wire mesh.
To enhance their fire-stopping abilities, fire doors are flush with the frame. Any or all gaps are filled with silicone-based fire-resistant sealant. These are often accompanied by a keluar (exit) sign and an intumescent strip attached at the bottom of the door, which expands when exposed to heat to prevent smoke from seeping underneath.
Fire doors are commonly designed to include a closing mechanism. Usually fitted at the top of a door, these spring-loaded or hydraulic mechanisms force the door closed, preventing fire and smoke from passing from one area to another.