Steel Buildings in Europe

Part 6: Fire Engineering 6 - 9 External fire spread In order to control the size of a fire, national regulations normally require that the potential for fire spread between buildings is considered. In some cases, the fire resistance requirements for external walls will depend on the distance between buildings reflecting the fact that radiated heat is the main fire risk for the adjacent building. As the space between the buildings increases the intensity of the heat flux diminishes. Means of escape Prescriptive regulations also require that escape routes are provided to allow occupants to move to a place of safety outside the building in the event of fire. Depending on the building usage and the likely number of occupants the regulations may prescribe the number of exits required, the width of the stairs or corridors used as fire escapes and the maximum distance that needs to be travelled from the most remote point in the building. Table 2.3 gives an appreciation of the importance of travel distances in the design of escape stairs. Note that the value of the maximum travel distance in different countries may vary. Table 2.3 Typical maximum travel distances (m) to fire-protected areas or escape stairs Type of building One direction Multiple directions Residential 9 18 Office 18 45 Shop 18 45 The design of means of escape influences the layout of the building plan in terms of arrangements of doors, corridors and, in particular, the number and locations of staircases in the building. Access for emergency services Prescriptive regulations require that access and facilities are provided for the fire service, so that they can carry out fire-fighting and rescue operations. In multi-storey buildings there may be a requirement for a fire-fighting shaft, including a staircase and/or lifts to allow fire fighters a means of getting personnel and equipment to the floor affected by fire. The fire-fighting shaft may also contain a wet or dry water main running vertically up the building which can be used to provide the necessary water supply for fire fighting operations. The fire fighting shaft is designed to given fire-fighters a place of relative safety from which they can launch fire-fighting operations into the fire-affected compartment. Fire-fighting shafts usually take up more floor space than a normal stairway and lift shaft, so these requirements can have a significant impact on building design and need to be considered at an early stage. The area around the building must also allow access for emergency vehicles, usually to within reasonable proximity of the wet or dry water main inlets.