A door or shutter provided for the passage of persons, air or things which, together with its frame and furniture as installed within a building, is intended when closed to resist the passage of fire and/or gaseous components of combustion and is capable of achieving a specified level of performance to those ends.
Fire doors are provided within strategic locations within a building (or as entry to additional areas of a building) where passage through a line of fire resisting construction is to be achieved. Such locations can include, surrounding the enclosure to a protected escape route, lobby or stair, within a line of compartmentation, or at the access to a protected shaft. The overall objective of the fire door is to maintain a level of fire resistance as required i.e. restrict the passage of smoke and flame within the building either for the protection of life or property.
It is important to understand that a fire door is defined by the performance of the door set as a whole. This includes the door leaf, door linings, all fixings and apertures. A fire door may also be designed to restrict the passage of smoke. All specified fire doors (except in single dwellings, houses) should be indicated by signage, for example Fire Door Keep Shut. They are designed to meet the requirements for a particular part of a building and may be fire rated as, for example, FD30 for a fire door of not less than 30 minutes fire resisting integrity or FD30S for the same fire door also designed to resist the passage of smoke at ambient temperatures.
There is a common misconception that the periods of fire resistance quoted for fire resisting elements (including doors) relate directly to the period of time for which they will resist the passage of fire and/or smoke during a real incident. Ratings for fire doors relate only to the severity of the furnace used to carry out the fire resistance test and provide only an indication of the fire resistance rating defined by a British Standard Fire Door Test. Fire door ratings provide guidance for the period of time the door has resisted fire and smoke in test conditions and are therefore only intended to provide a comparison between one product and another, not an absolute indication of performance in a real fire.
It should be noted that in the case of some the entrance doors to flats and some service risers or stairs the fire resistance of the fire door may only be half that of the line of compartmentation in which it is situated i.e. a 30 minute rated fire door in a 60 minute wall.
Fire doors can be constructed from many different materials including timber, steel and composite materials; all fire doors are engineered to achieve the rating to which they are designed and tested. Most timber fire doors only provide 30 to 60 minutes fire resistance.
Timber doors, when exposed to heating effects can shrink towards the fire, whereas steel doors distort away from the heat. Composite doors can distort in either direction, or not at all.
Timber fire doors should always be provided with intumescent seals around the intersection of the leaf and frame reveal as well as around glazed apertures or penetrations such as letter boxes, viewers and air transfer grilles. The purpose of the intumescent materials is to seal the edges of the door from flame and smoke and to protect the timber from erosion around ironmongery and to expand and fill any voids where flame and smoke can penetrate.
- Correctly installed and maintained fire doors should help to contain a fire within a compartment
- Damage, patching, poor maintenance or poor workmanship with regard to fire doors may allow for the spread of smoke between compartments
- External fire door exits may be difficult to access from the outside
- A fire door may be held in place by the intumescent strips rather than ironmongery and will not open in the usual manner and may fall out of the aperture if dislodged