There are typically six types of external wall fire that may spread rapidly and with great intensity up and across the face of the building, in some cases leading to re-entry into the accomodation. In recent years there have been several fires in the UK of this nature, although none have come close to equalling the tragic scale of a fire such as Grenfell Tower in London (2017). However, it is clear to see that each fire type may present varying levels of risk and challenges, including external wall fire and multiple floor fires, but all will place demands on firefighters and incident commanders to utilise the most effective tactical options in achieving the best outcomes.

• Typical window to window limited vertical fire spread
• Combustible window sets ground to roof
• External ACM or MCM wall cladding rainscreens over insues. Thislation
• External rendered wall systems or High Pressure Laminates over insulation
• Glass curtain walls
• Combustible Balconies with high hazard storage incuded in some cases

Protect the means of escape as a priority

The primary option of fire suppression may not always produce the best outcome where external wall fires are concerned. Particularly in single stair residential buildings the primary concern may well be the protection of the vertical and horizontal escape paths.

The  concept of ‘stairwell protection’ primarily suggests firefighters  should locate and secure, or establish, and maintain, at least one means  of vertical egress from a fire involved building. ‘Stairwell  protection’ as a strategy differentiates itself from ‘stairwell search’  which is often a reactive response to fire survival guidance calls. Stairwell search is where teams of firefighters are deployed to areas above the fire  sector to search for, and assist or rescue, occupants who are  trapped or threatened by fire or smoke. 

Stairwell protection is primarily a proactive strategy that is directed at protecting  occupants who may already be self-evacuating, whilst at the same time  securing stairwells for an emergency evacuation should it ever be  needed. The strategy is aimed at using all available means and resources  to mitigate smoke infiltration into stairwells.

• Firefighting procedure places the first and second attack hose-lines to be deployed from the fire floor itself and not from floors lower down, with a Bridgehead being located three floors below the fire floor.
• Using a dividing breeching, taken aloft with the reconnaissance team, to enable two hose-lines to be fed from one riser outlet at the same level
• The concept of door fire curtains to protect stair doors where the riser outlet is still located in the stair, or in particular where long corridors exist and the fire apartment door opens into the corridor, is currently being trialled in the UK and Ireland.
• The deployment of Stairwell Protection Teams to patrol and search stairs above the fire floor for self evacuating occupants and to control venting in the stair and escape routes was initiated in 2005. Originally called Rapid Ascent Teams (RATS) after the Chicago Fire Department model, these firefighters may already be in position to answer Fire Survival Guidance calls, should they occur.
• The key to ICE (RICE) is in protecting the stairway in single stair buildings and controlling self evacuation routes by keeping them smoke free for as long as possible, even if the fire attack is delayed for life safety reasons.

It is certain that following the Grenfell inquiry and the upcoming technical review of building fire safety guidance, one debate still to be had that may influence the firefighting facilities (B5) guidance on rising mains will surround the following proposals.

• That rising fire mains should be a minimum of 150mm in diameter.
• That rising fire mains should have at least two outlets per floor level.
• That rising fire main outlets should be located in a firefighting lobby (as in commercial buildings) or in a ventilated accommodation corridor/lobby in residential buildings, sited immediately adjacent to the firefighting stair door.

The primary reasons for this are to ensure adequate flow-rate for two hose-lines (attack and safety lines) is provided at the same floor level in a position that will ensure smoke does not travel into the stair. In this respect, the inwards movement of firefighting stair doors to provide 'make-up' air for smoke shafts must be closely looked at for in some situations relating to intense fires, the stair door could be breached by excessive smoke movements into the stair.

When firefighters are expected to deal with external wall fires they must be adequately trained, equipped and prepared for the worst case scenario. A move away from a pre-conditioned fire extinguishing intervention has to allow for the tactical consideration of alternative options at a very early stage. It may be that when a fire has spread externally beyond 3-4 floors of fire and is continuing to do so, out of reach of firefighting streams, alternative actions are needed and quickly. Utilising what building protection remains operating and functional is perhaps a key consideration and it is acknowledged that some cladding fires are not extinguishable by conventional methods.

Self-evacuating occupants are something we are now being faced with far more frequently. With this in mind we must ensure our tactical approaches continue to support the objectives of basic fire safety principles in maintaining escape routes smoke free for as long as possible. 

This should be supported at all times by both the building design and by our own on-scene actions.

The following Article was Published by Hemming Fire Journals  

From Fire and Rescue Magazine 2011:

Paul Grimwood 05 April, 2011

‘In situations where single exit stairs may become compromised by smoke as firefighters open up the fire compartment, the evacuation of the entire building above the fire floor, and possibly below it, may need to be prioritised‘.

“If fire has spread beyond the floor of origin, the overriding objective is to maintain escape routes for occupants clear of smoke where resources, staffing or available flow-rate at upper levels are compromised by such rapid fire growth”.........

"A safe outcome in High-rise response relies heavily on the fire resisting performance of interior compartments in tall buildings, writes Paul Grimwood, Principal Fire Safety Advisor for Kent Fire and Rescue Service. We are constantly reminded just how difficult and dangerous fighting a fire in a high-rise building can be, and over the past decade there have been several serious fires in high-rise buildings. But when analysed statistically, the risks of death, injury and property damage may appear lower in high-rise buildings than in other buildings of the same occupancy type.

However, it is becoming clear that the time needed to establish a safe and effective firefighting intervention on the upper levels of a tall building places great reliance on the fire resisting performance of interior compartments. After the fire has been located and the forward command bridgehead is being established in a safe location – 2-3 floors below the fire floor– any building occupants that may be at immediate risk by subsequent firefighting actions must first be evacuated to safety before intervention occurs.

These are time-dependant operations that require adequate resources based on a critical-task analysis. The numbers of firefighters needed to establish the basic evacuation of primary risk zones; confine the fire; and implement an intervention are wholly dependent on the levels of horizontal and vertical fire resistance within the structure – and any fire suppression systems that will limit fire spread. Most recently, several high-rise fires have demonstrated how high fire loads, coupled with a trend to provide greater expanses of glazed outer walls, can lead to faster growing fires and vertical exterior fire spread that causes immense problems for firefighters working inside the building. When this occurs, the provision of a high standard of interior fire resisting compartmentalisation is absolutely crucial to firefighter and occupant safety. In such cases the primary tactical objective may be to contain the fire as much as possible, within fire resisting sections to a controlled percentage of the building. 

If fire has spread beyond the floor of origin, the overriding objective is to maintain escape routes for occupants clear of smoke where resources, staffing or available flow-rate at upper levels are compromised by such rapid fire growth.

Fire resisting compartments and/or sprinklers.

Where fire resisting compartmentalisation is reduced or removed from key areas within tall buildings (such as that provided in occupant escape or firefighter access routes), there should be adequate compensatory provisions in the form of sprinklers to counter the risk of unconfined fire spread. Without such provisions in both residential and commercial high-rise then the potential for trapped occupants and multi-floor fires is clearly an increasing threat.

*          In a five-room 70m2 apartment fire the ventilation controlled heat release throughout the space can reach 15 MW within less than a minute following a single room flashover.

*          The spread of fire in large open-plan commercial floors is primarily dependent on fire load and ventilation. The quantity of water needed to deal with such fire spread is easily calculated using established engineering principles. In general, water flow-rates of at least 5 lpm per m2 of fire involvement are needed for effective suppression. This means a 500 lpm hose-line can, in general, deal with 100 m2 of fire during steady growth or steady state burning rates (not necessarily during the flashover stage), or a 1,000 lpm hose-line up to 200 m2 of fire.

*           In an open-plan floor area containing office work-stations, a fire can develop so rapidly that it will be beyond the control of a firefighter’s hose-line within 8 to 10 minutes of surpassing the incipient stage of fire development.

*          Commercial floor space should ideally be protected by sprinkler provisions but where in excess of 100 m2 this should be legislated. An alternative approach might suggest internal compartmentalisation providing 60-minute FR to >100m2 compartments, which may compensate where sprinklers are not provided.

*          Where corridor sub-dividing smoke or fire doors are removed to enhance the effects of smoke ventilation systems, and where alternative exits and stairs are non-existent due to reliance on such systems, any rapid spread of fire and smoke can soon cut occupants off from their only means of egress and make it very difficult for firefighters to reach them internally.

HIGH-RISE FIREFIGHTING TACTICS

When faced with a fire on an upper level in a high-rise building it is important that the fire service promptly responds with adequate staffing, resources, and weight of attack. It is equally as important that an effective chain of command with clear communication channels between each sector and any location is established at key points, namely marshalling; lobby; staging; bridgehead (forward command); and search commands. Beyond these assignments, key functional and support officers will be needed to support ongoing operations.

The initial tactical objectives will be to carry out reconnaissance in order to locate the fire and stabilise the fire floor by taking control and clearing occupants from the most immediate area of risk. This may also entail evacuating any occupants from the area immediately above the fire (primary risk zones).

From this point the incident commander must assess the situation and decide on the most appropriate tactical approach to be taken:

'ICE' Primary Command

*          Intervention

*          Containment

*          Evacuation.

Tactical-decision-tool – ICE ....

It can be seen that following the reconnaissance and assessment stage there are three main tactical options open to the incident commander. The decision-tree approach should be based upon the stage of fire development, construction, location and status of known remaining occupants, resources available, likelihood of success and the existence of compartmentalisation and/or sprinklers. It is important that safe systems of work are utilised at all times.

INTERVENTION

In confined fire situations the intervention option may appear the primary solution. However, it is critical that before any decision is made to open the fire compartment or involved fire area, that the effect of wind direction and velocity is taken into account. If a wind of any great extent (>5 mph at 10m) is hitting the face of the building where the fire compartment is situated, then consideration must be given to delaying, or restricting/preventing an entry for intervention purposes. An exterior wind – likely to become stronger at heights greater than 10 metres – may create some rapid fire development that will be totally unmanageable at the fire floor. Recent research by NIST in the USA demonstrated that untenable conditions for firefighters were created where exterior winds pushed fire directly at firefighters in such circumstances. In effect, unless they were able to find some immediate point of refuge, firefighters remaining in the air-flow path filled by the blow-torching of flames would be rapidly overcome by the heat and fail to escape. Even temperatures in the corridor serving the apartments were untenable to firefighters during NIST tests.

Therefore, unless there is an immediate and over-powering requirement for an intervention to locate and rescue confirmed saveable life, the tactical priority should be that of evacuation of primary risk zones, or possibly containment. Where a rapid intervention for saveable life is undertaken, it is crucial that local procedure is followed, based on clear guidance or directives. The UK National GRA 3.2 for high-rise building fires provides guidance that compartment fire entry should be implemented with at least one charged hose-line as protection. It goes on to advise that where warning signs of rapid fire development exist, a secondary back-up hose-line should be provided prior to opening the fire compartment.

EVACUATION

The evacuation of the primary risk zones is an early tactical solution that will ensure – where fire does spread out (either externally or internally) from the compartment of origin –  that all occupants have been removed from adjacent zones. These areas include all apartments/compartments that are not protected by corridor sub dividing doors and the apartment/compartment directly above the involved fire area. Corridor sub divisions that have been removed to enhance ventilation of the corridors via smoke shafts, and secondary exit stairs that have been removed from the prescriptive requirement, may create long corridor runs with apartment doors either side that require evacuation. This can be a time-dependant, resource-hungry operation. Where sub-dividing doors are provided in the corridors this may halve or even quarter the size of the primary evacuation zone and allow firefighters to rapidly evacuate much smaller areas with less resources deployed.

In situations where single exit stairs may become compromised by smoke as firefighters open up the fire compartment, the evacuation of the entire building above the fire floor, and possibly below it, may need to be prioritised. This will depend on a careful assessment of risk, based on anticipated fire conditions, exterior wind conditions and building layout. Where a code compliant sprinkler system is installed then any fire development should be limited in size, although toxic fire gases may still be emitted prior to firefighters completing suppression. Two or more exit stairs may provide alternative escape options for occupants but without effective fire separation in the form of corridor sub dividing doors, these alternative exits may become unusable if large quantities of smoke and heat were to transport into the corridor.

Secondary risk zones are areas where occupants may not be at immediate risk but this could change and such areas may become primary risk zones at a later stage. For example, escape stairs can become compromised by smoke and heat, necessitating top to bottom searches by firefighters where occupants might remain in the stairs (for whatever reason). A fire in a 37-storey office tower in Chicago in 2003 saw five occupants lose their lives when they became trapped in the stairs. In some situations smoke can fill a stair shaft top to bottom, even below the fire floor, where air-flows into the stairs are driven by external wind effects. Total building evacuation (either before or after intervention) occurs may become an option in producing the best outcome and should always be a tactical consideration. However, key features in the building design will play a part in how such an option may be undertaken safely and effectively.

CONTAINMENT

Where a fire is threatening to spread out from the compartment of origin to affect the floor above then an early containment option may provide the best outcome. It should be remembered that early access to the area above the fire may have been achieved during any evacuation of primary risk zones. If this is the case then the deployment of a charged hose-line onto the floor above the fire and into the compartment directly above the fire compartment may be a tactical consideration. In this situation it is critical to ensure that the fire remains contained and that no attempt is made to open and enter the fire compartment for intervention if it is likely to compromise evacuation routes. However, the tactical objective is to prevent or halt the vertical spread of fire up the face of the building and with a well-placed hose-line above the fire floor, this is very achievable. The ability of firefighters to operate effectively against fast-spreading fires on upper floors of tall buildings is directly dependent on adequate compartmentalisation, particularly in escape corridors, maximum sized fire resisting compartments to >100m2 and/or sprinklers in all high-rise over 18m.

EUROFIREFIGHTER 2008 -

'The deployment of firefighters above the Bridgehead for Search and reconnaissance must be carefully controlled under the command of the S&R Commander. All firefighters should don breathing apparatus in case needed and work in accordance with RAT team principles'.

High-rise firefighting Rapid Ascent Teams (RATS). Post 9-11, Curtis Massey introduced the RAT team concept. In EuroFirefighter 1 this high-rise strategy for searching and evacuating stair-shafts and areas above the Bridgehead/Forward Command Post, we covered the basics (p315 on). 

‘It is critical to protect the escape routes at all times where a large number of occupants remain above the fire’. 

As soon as the fire floor has been located and the Bridgehead has been established in the first few minutes we must assign a Bridgehead Commander to deal with the fire sector and a Search and Evacuation Commander to deal with all floor levels above.

These two commanders must work together to address the conflict between fire attack, immediate rescues and protecting the egress routes. In a single stair building the conflict can be life critical. The design of the building may not allow both fire attack and keeping escape routes and stair-shafts clear of smoke and it is here a line should be drawn to determine which is most critical. 

Where the fire is contained the primary risk areas (adjacent corridors and lobbies) should first be evacuated prior to fire attack. Where the fire is spreading beyond the apartment or area of confinement, the escape route may become the priority. If the fire is spreading beyond the fire floor or via the exterior wall, again protecting the escape route for evacuating occupants becomes a priority.

If we are to ensure stair-shafts are clear and upper level occupants remain safe we should deploy RAT firefighters to work above the fire equipped with breathing apparatus in case needed and basic tools, for they may be working for long periods on upper levels. We are now protecting their escape route as well.

Where voice alarms exist under fire service control they can be used to offer guidance and support to remaining occupants, either to stay where they are or to make their way down any particular stair-shaft determined as safe.

More From EuroFirefighter 2008

'When we are faced with a serious fire at ground level, our firefighters often encounter great difficulties and exposure to some element of risk. However, when they are faced with that same fire thirty storeys above ground, the physiological and logistical demands are far greater and the difficulties and risks are greatly magnified. 

 There may be long time delays between a fire commander's chosen strategies becoming viable tactical operations on the fire floors. There may be changing circumstances involving fire spread during this time lag that requires the strategy to be amended. There will be a great demand for adequate and effective staffing to accomplish even the most basic operation, and then, where firefighters are working hard, the need to support them in a sustained attack will treble the staffing requirement.  

The communication process at a high-rise fire will inevitably break down and the pre-plan must therefore ensure that critical tasks, such as searching stair-shafts, elevator lifts and roof, allow for well practised firefighters to adapt and function alone in small teams that are, on occasions, without overall fire command supervision". 

Paul Grimwood 

Quotes from Articles and Publications 1990-2011