What firefighters need to know before entering a building
The building regulations (fire safety) in the UK specify certain requirements for the provision of adequate access and facilities to assist firefighters during firefighting and rescue operations. It is important that these minimum levels of firefighting access and facilities are maintained during both construction and occupation phases of a new build. It is also important to review how a building is constructed and what materials are being used.
At all stages of the build, firefighters should familiarise themselves with building methods and materials used, as at completion the relevant parts (to firefighters) of a fire-involved structure may be hidden from view. As a building material, wood or perhaps more appropriately timber, has some excellent properties. It has a high strength to weight ratio; it can easily be shaped and connected; it is one of the most sustainable resources and is environmentally friendly as well as being aesthetically pleasing.
Timber is increasingly becoming a more desirable construction material as international architects and designers realise that timber has significant potential benefits in sustainability and speed of construction. Traditional schemes for timber buildings as low-rise (two-stories or less) and mid-rise (three- to five-stories) are now being extended with schemes for new high-rise buildings, also referred to as tall, timber buildings (six-stories or greater). In fact, extremely tall timber framed buildings are now being constructed in many of our major cities.
It is almost certain though that as these buildings age they will become more at risk of fire-spread in cavities, voids and redeveloped sections of the structure, and the future may hold some surprises for the fire service from an operational perspective.
Firefighting Access
It is essential that the fire service is able to effectively access the roads and approaches to any particular building or risk, so that they are wide enough and able to support the weight of fire engines. It is inappropriate to provide access routes that are blocked by parked cars or possibly cause the fire engines to enter via a very congested retail car park. On arrival, the firefighters require access within 45 metres of a residential building, measured from the fire engine to the furthest distant point, within the structure. The intention is to allow a 60-metre run of hose-reel from the fire engine to reach all points within a building.
If this isn’t viable, then a dry rising fire main or perhaps sprinklers should be installed. There are also requirements to provide firefighting access to the building’s perimeter (engines and height vehicles) based on a percentage of the total size of the floor-plate.
Firefighting Shaft
In buildings over 18 metres, or where deep basements are more than 10 metres below grade, or in commercial, shop, industrial or storage buildings more than 7.5 metres in height, a firefighting shaft is required.
A firefighting shaft provides firefighters with protected vertical access to all floor levels from which to mount their firefighting search and rescue operations, providing two hours of protection (fire resistance) from fire, heat and smoke. Within the firefighting shaft itself certain facilities are provided to further assist firefighters:
- Firefighting Lobby (ventilated) – firefighting lobbies should have a clear floor area of not less than 5 m2.
- Firefighting stair
- Rising fire main (in some cases the fire main outlets may be provided in the corridors, outside of the firefighting shaft but immediately adjacent to the shaft door. This is a non-compliant arrangement with local fire service approval/preference).
- The furthest point in any building from a fire main located in a firefighting shaft must be limited to 60 metres (three hose-lengths).
- May be provided with lobby protection (unlikely in apartment buildings)
- Will be ventilated either manually in multi-stair buildings, or automatically by smoke detection in firefighting shafts or single stair buildings
- May be pressurised (positive air outflow to prevent smoke inflow)
- Firefighting lift (in flats or apartment blocks the firefighting lift may not be located within the firefighting shaft, but if this is the case then the lift should be no more than 7.5 metres from the firefighting stair door.
Firefighting Lift
There have been a range of design codes and standards for firefighting lifts, dating as far back as the 1970s. These were in fact ordinary passenger lifts with a firefighter recall button allocated at ground level. Currently firefighting lifts are based on a European standard BS EN 81-72:2015. A firefighting lift, unlike a normal passenger lift, is designed to operate so long as is practicable when there is a fire in parts of the building beyond the confines of the firefighting shaft, as it is used to transport firefighters and their equipment to a floor of their choice.
The lift can be used in normal times as a passenger lift by the occupants of the building and during a fire, it may be used prior to the arrival of the fire and rescue services for evacuating those with disabilities and impaired mobility (BS 9999). This feature will coordinate with fire alarm activation and may not ground immediately. It should not be used for moving refuse, or for moving goods. In buildings provided with a single lift its use for the transport of goods should be avoided unless essential, lift lobbies should be kept clear, and when used for moving goods the doors should not be propped open to ensure that the lift remains at a particular level.
The BS-EN standard (2015) stipulates certain requirements that are sometimes at conflict with UK building regulations; therefore, the standard is not fully complied with, notably:
- The firefighters lift is located in a well with a ‘safe area’ (lobby) in front of every landing door which is used for firefighting operations. In front of every landing door a safe area, a fire shutter or a fire door shall be provided (see firefighter lift entrapment below).
- The purpose of safe areas is to protect the lift well, firefighters and those who may be waiting to be evacuated against fire, heat and smoke and in addition to allow the self-rescue of firefighters/occupants if needed. The minimum dimensions of each safe area are given by national regulations.
It is essential that firefighters familiarise themselves with the operation of lift controls when they visit buildings, the procedure for taking control of the lifts and the escape procedure from a stalled lift. Where a roof hatch for firefighter escape is installed (in some areas the installation of a firefighter escape hatch may not be approved by the local fire service) the operation of the escape hatch and the access to the car roof, both from inside the car and externally, along with electrical supply isolation is all important knowledge.
There have been several recorded occasions when water from a landing valve, hose lines, etc., has entered the lift well and caused malfunction of the installation when it reached electrical door interlocks, car controls, etc. It is therefore necessary to minimise both the effects of water on lift operations, and the probability of water entering the lift well in the first place. It is for this reason that the lift lobby is one area where sprinklers might not be installed, and special preventive measures should be installed to reduce the likelihood of lift failure.
A firefighting lift switch should be provided to enable the fire service to obtain immediate control of the firefighting lift(s) in a firefighting shaft.
The car controls of the firefighting lift should become active only after it has arrived at the fire service access level and the firefighting lift switch has been operated. Once the firefighting lift has arrived at the fire service access level, its doors should open and it should then operate as follows:
- Fire personnel entering the lift car should be able to register a call to any selected landing in the building by sustained pressure on a car control until the car doors have fully closed
- If a car control is released before the doors have fully closed, the doors should immediately reopen and the call should be cancelled
- It should be possible to register a new call on the car controls which should cancel the previous call.
- The lift should travel in the shortest time to the call registered, and should stop at that floor.
- The doors should remain closed unless they are operated by continuous pressure on the ‘door open’ control
- It should not be possible to open the doors without sustained pressure on the control
- Release of the ‘door open’ control before the doors are fully open should cause the doors to automatically re-close. This allows fire service personnel to observe the situation immediately outside the lift landing doors in the firefighting lobby
- Once the doors are fully open they should remain open until a new call is registered at the car control station
- All lifts may operate slightly differently and firefighters should familiarise locally with firefighter’s car key switches, where provided
Upgrading existing Firefighting Lifts
These are recommended minimum design requirements where it is entirely impractical to upgrade existing firefighting lifts to current BSEN standards:
• Primary and secondary power supplies
• Water protection measures (e.g. IP rated wiring and controls, drainage and preventive measures)
• Fire fighter recall switch at access level
• Fire fighter in-car controls
• Fire fighter communication system
• Floor indicators For detailed guidance of upgrading existing firefighting lifts to a minimum acceptable standard, reference should be made to BS 8899:2016.
Firefighting Stairs
Firefighting stairs are those that accommodate a firefighting main, where firefighting shafts are considered unnecessary. They must be at least 1100mm wide and provide a minimum of 60 minutes fire resistance. The furthest point in any building from a fire main located in a firefighting stair must be limited to 45 metres (two hose-lengths).
Rising Fire Mains (Standpipes)
The objective of having rising fire mains in buildings is to reduce the physiological stresses placed on firefighters who have to transport quantities of firefighting hose, nozzles, adaptor couplings and other equipment to the fire area within a building whilst each wearing over 50kg of protective equipment.
Research has demonstrated that in doing so, inner core body temperatures are sometimes already near dangerous levels, at just about the time they are committing themselves into the extreme heat of a fire compartment. In residential buildings, firefighters should not be expected to travel further than 45 metres from a fire service appliance (fire engine) or fire main outlet, unless the fire main is within a firefighting shaft, where 60 metres is accepted as the maximum hose-lay distance into the accommodation.
In commercial and industrial buildings, firefighting access limitations are addressed by perimeter access to prescribed percentages of buildings, depending on size.
In tall buildings in the UK in excess of 18 metres in height a dry rising fire main is required and in new buildings over 50 metres a wet rising fire main is now prescribed (over 60 metres pre-2006). Dry mains now have design capacity to be charged up to 12 bars (from 2015)20 from fire service pumps but at this time, the majority of fire services in the UK are unable to charge to more than 10 bars due to pressure limitations on hose-line and pumping configurations.
The ability to pump to 12 bars will add approximately a further 2 bars to outlets at the highest levels and increase flow-rate capacity from nozzles quite dramatically, in some cases doubling the flow.A minimum 100mm bore fire main is recommended for each 900 square metres of floor plate, providing capacity for a total 1,500 Litres/minute (1.67 L/min/m2) flow supplying two hose-lines of 750 L/min or three at 500 L/min. Importantly, the maximum hose-lay distances (45 or 60m) determine the number of fire mains needed.
However, no consideration is given to occupancy type or fire load density and the same provisions are equally applicable to apartment buildings, as well as open-plan office floors. Therefore, a fire engineered strategy should be used to provide adequate water (L/min) to match the fire loading and fire growth rates for each individual project.
Article written by Paul Grimwood from Euro Firefighter 2