Stairwell Design: A Firefighter’s Perspective
Brent Brooks HighRise Firefighting
"Understanding is a two-way street"
I referenced this quote because making our buildings safer requires collaboration among various professionals, including city planners, engineers, architects, builders, firefighters, and the individuals who live and work in these buildings. Everyone involved should collaborate with an open mind and concentrate on discovering the best solutions.
Evacuation and fire responses are interconnected. Stairwells serve as vital pathways, enabling firefighters to reach the scene while simultaneously providing a safe exit for occupants.
The field of building construction and its systems is continually evolving. Fire-rated separations are based on time limits. Smoke control relies on both pressure and smoke containment. Sprinkler systems play a vital role by providing critical time for fire department response and curbing the spread of flames. Detection devices offer early warnings, alerting both occupants and fire services.
Areas designated for rescue/refuge are typically located within or near stairwells, serving those who cannot evacuate independently. The anticipated number of occupants in the building plays a crucial role in determining the size of the evacuation routes, including the number of staircases required. It is crucial that all these protective measures function together.
Let's take a moment to contemplate the single stair. Have we asked the right questions? Have we included the experiences of the end users, our first responders? Have we consulted the end users about operating within a single-stair design? I’m asking because I study buildings and firefighting tactics worldwide, and I’m struggling to grasp the advantages of the single stair. I remain open-minded and evaluate the pros and cons based on my studies and experience. My findings indicate that the scale leans heavily against the single-stair design. What am I missing?
I’ve seen stairwell design change over time in my career, some positive and some negative.
The positive changes I've witnessed include expanded real estate for rescue/refuge areas in stairwells or close to stairwells that can accommodate individuals with disabilities. The larger size also enables occupants and firefighters to share the space. The stairwells feature a well-hole spacious enough for a vertical stretch of firefighting hoses from the ground level in case of a catastrophic failure of the building’s standpipe system. A well-hole facilitates additional firefighting tactics. Having more than one stairwell assists firefighters in flanking a negative flow path and allows them to establish a positive flow path for ventilation. Voice communication has been introduced for individuals sheltering in the rescue/refuge area. Evacuation chairs have been pre-staged for those who need them.
The negative change I have observed over the years is the restriction of firefighter-keyed access and the lack of handles on exterior doors to stairwells. This design forces firefighters to rely on elevators to reach floors above the first floor, then locate the stairwells and descend to open the doors. If the elevators fail, they must breach the exterior door, which is time-consuming and challenging with outward-swinging doors. Outward-swinging doors are essential for evacuation. Firefighters would greatly benefit from having key access and handles. Additionally, forcing the door would be necessary in the event of a fire on the second floor.
The handle is not just meant for opening the door. The handle is also used as an anchor point for securing the door in the open position when operating our powerful Positive Pressure Ventilation fans (PPV). Traditional door chocks do not work under these forces. Damaging a door by breaching it prevents it from closing entirely. The damage is costly and will disrupt compartmentalization, which can lead to smoke spreading. This design wastes valuable time. Firefighters do not use elevators to access the first four floors of any building. These fires necessitate access from the exterior stairwell. Exterior stairwell access is critical for our ventilation tactics.
Reducing the width of the stairwell can hinder evacuation and fire response. I have witnessed baby carriages, shopping carts, and luggage being brought downstairs during a fire, significantly slowing the evacuation process. I have observed the consequences of slow evacuees and the negative chain reaction caused by the bottleneck of evacuees. I recognize how fast panic can spread and what leads to a stampede.
I can tell you that occupant behaviour is unpredictable. The longer it takes firefighters to extinguish the fire and clear the smoke, the more occupants take their safety into their own hands. Even with EVAC announcements made at regular intervals and reassurance from a fire dispatcher over the phone, occupants will eventually make their own decisions.
The width of the stairs should permit firefighters to ascend while evacuees exit simultaneously. In a perfect world, Firefighters announce an attack stairwell, hoping that evacuees will use other stairwells. Still, the stairs of older buildings are not marked, and communicating the geographical location using compass headings, such as North, South, East, and West, is not understood. Even firefighters get confused once inside the structure. Add smoke into the mix and expect occupants in all stairwells.
I understand and appreciate the occupant's perspective. History has shown that sheltering in place is ineffective once the fire spreads beyond a room and its contents to impact the structure itself. The Grenfell fire in London, England, where 72 people lost their lives, exemplifies a failed shelter-in-place tactic and highlights the disadvantage of a building with only one stairway.
The absence of a well-hole prevents firefighters from performing the quickest and most effective improvised standpipe. Firefighters can utilize the well-hole to stretch a hose up, or a coupling drop down. Without this well-hole, they require additional hoses and personnel, which slows response times and gives the fire a greater advantage due to the prolonged delay. More fire hoses result in increased friction loss, and the added complexity of hydraulics complicates water delivery while also limiting our tactical options.
To put this into perspective, when firefighters use six lengths of 65mm (2.5”) hoses on a well-hole, they can safely deliver water to the 25th to 30th floor under normal operating pressure. However, when no well-hole is available, firefighters must perform a closed-well stretch; hydraulics only allow us to safely reach the 11th floor. This poses a problem for podium-based high-rise buildings, as we may need to perform a closed-well stretch in the podium portion to the transfer hallway that connects to the tower’s stairwell. The solution is a well-hole that provides a diameter of 15.24 cm (6”). Buildings taller than 30 stories will require a well-hole to accommodate a large diameter hose. I toured Merdeka 118, the second-tallest building in the world, and was impressed by the stairwell design. It can accommodate stretching large-volume hoses in the event of a catastrophic failure of the standpipe system.
History shows that if the fire department does not apply sufficient water within 20 minutes, smoke will start to fill the stairwells and quickly spread throughout the building. Occupants who hear the alarms, see the strobe lights, smell smoke, or spot smoke will eventually begin to question their decision to shelter in place. Additionally, outside influences from friends and family urging them to evacuate may encourage people to leave their current location. The more occupants and firefighters move through each compartment, the more smoke will spread. Every minute is critical. Protecting the stairwells is vital.
The preparation for change is ongoing. We need to address outstanding problems. Fire departments are working towards meeting the recommendations set forth in NFPA 1710, which outlines the required staffing levels for firefighting in various types of occupancies. According to this industry standard, the initial fire response for a low-hazard single-family house fire specifies 15 firefighters, while a garden apartment-style building specifies 28 firefighters. The initial staffing level of 43 or more firefighters is necessary for high-rise buildings. Additionally, the standard specifies the required litres per minute (LPM) or gallons per minute (GPM) for fire suppression on the fire floor and the floor above. It also specifies the size of the hose line and nozzle package needed to meet this standard.
The end user also plays a crucial role in ensuring the realism and practicality of setting up hose lines and establishing a water supply for fire extinguishment. We aim to find an effective solution by assessing staffing levels alongside the necessary water volume for battling a fire. Additionally, it's important to evaluate the Fire Department's equipment and understand its capabilities. The mathematical calculations must align with the specifics of the building in question. Armed with this information, we can formulate effective tactics for success, which include strategies for rescue, evacuation, and shelter-in-place and ventilation scenarios.
A well-designed stairwell is clearly marked with a designated name and engineered with pressurization to prevent smoke from spreading. It provides ample space for both firefighters and building occupants. The stairwell also features essential components such as communication systems for individuals with disabilities, evacuation chairs, and the ability to run hose lines up or down a well-hole. Furthermore, it facilitates ventilation by firefighters and offers exterior access via a handle. They should include luminescent markings on railings and stair treads that glow in the dark. A small section of security glass to provide firefighters and occupants with a visual of the hallway and stairwell condition without having to open the stairway door.
Fire departments are struggling to keep pace with new technology. Lithium-ion batteries exemplify something introduced without firefighting tactics. We must work together to ensure clear communication among all professionals involved. Our primary goal is to discover ways to support firefighters and enhance people's chances of survival during a fire.
Remember, understanding is a two-way street.
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