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  Size-Up: Updating An Old Acronym

Size-up is the process of gathering information that will assist firefighters and fire officers in making efficient, effective, and safe decisions on the fireground. It is the foundation for the officer's decision making. Because of the obvious urgency of responding and going to work at an emergency incident, decisions on the fireground must be made quickly, with a continued emphasis on their efficiency, effectiveness, and safety. To meet this demand, fire officers over the years have developed and used different means of gathering the information about a potential or actual incident. They would often seek this information from multiple sources.

As experience often demonstrates, it becomes evident early on in this business that waiting to gather information until the fire department arrives at an incident often proves to be reactive, unprofessional, and unproductive. Many fire officers gather specific information at different time intervals. The question is, When and where do we find the information?


Ideally, to aid in the decision-making process, a fire officer needs to have accurate and relevant information available well before the alarm is received. Many refer to this process of gathering information as "preincident documentation" or the "prefire plan." It is here the officer starts to seek data about the building and occupancy in question from current information available. Whether the information is in the form of a formal prefire plan and building inspection or from a previous incident, officers can begin to compile a comprehensive list of information that can aid them in the decision-making process well before an actual incident occurs.


A fire officer can add to his information base about the incident and the data needed for his size-up as the alarm is being transmitted. Some of the facts that can be determined then are the building's address, the type of occupancy, the time of the alarm, and the current weather conditions. Depending on your department's method of storing the information and communicating the alarm, information may also become available regarding the dimensions of the building, the class of construction, the building's contents, the area's water supply, and the possible presence of hazardous materials, to name a few.


Arrival on the scene presents the opportunity to gather more detailed information. Specifics such as the building's height and area, class of construction, and occupancy type; the location and extent of the fire; and any exposure concerns may quickly become evident.

(1) A Class 1 fire resistive building with a "hybrid" roof built of lightweight construction.

As firefighters and fire officers are assigned and go to work in their specific areas, the information-gathering process extends to include company or division/sector officers, who will provide progress and status reports to the incident commander (IC) from their assigned areas. Receiving additional and ongoing information will allow the IC to prioritize decisions, allowing for an efficient, effective, and-more importantly-safe outcome. The on-scene phase of size-up doesn't end until the incident is terminated and everybody goes home.


Did you think you were done? The process of gathering information can go one step further. After the incident is terminated, a postincident analysis can further the information exchange. Here, you review what you observed, what you did, the result of your actions, and what you have learned so you can make improvements for future incidents. This can be as simple as a review conducted at the kitchen table in the fire station or as detailed as a formal review, a documentation, or an illustration of the incident.

(2) Occupancy/construction association (movie theater) as viewed from side A.

The firefighter and the fire officer must realize that size-up of a potential or actual incident is not a concept you save until the alarm is transmitted. Beginning the information-gathering process early, continuing it throughout the incident, and then seeking additional information after the incident is over continues to be your best approach in preparing to deal with the unexpected.


Following are 15 points of size-up, which can be brought to mind using the acronym "COAL TWAS WEALTHS."


Throughout the years, we have been taught that we may encounter five classes of construction. Today, it is becoming increasingly more and more difficult to recognize them. Even in cities as old as Jersey City, a chief officer could be standing in front of what looks like a Class 3/ordinary construction building only to find that behind the brick are all lightweight structural components. Newer, lighter, or, as we will refer to it, hybrid construction methods are increasingly making their way into every town and city and are forcing us to change the way we do business.

(3) Same movie theater viewed from side D.

So where do we start to gather relevant and useful information about our construction concerns? It would be foolish to ignore what we already know. Even when buildings have been renovated from the original classes of construction, their inherent construction features are still present and must be factored into our decision making. Taking the information we have been taught in the past and continually adding the new concerns pertaining to the preengineered materials and methods used today is the fire officer's best weapon for factoring building construction into the size-up.

  • Class 1-Fire resistive is defined as a building built of masonry and steel in which the structural members are designed and protected to resist the maximum severity of fire expected within the building. These types of buildings include commercial and residential high-rise buildings as well as low-rise housing complexes.

  • Class 2-Noncombustible/limited combustible includes buildings built of masonry and steel in which the structural members (notably the steel) are not protected from exposure to fire. Construction features will ignite when exposed to a sizeable amount of fire. Because of the combustible roof deck commonly associated with this type of construction, it is referred to as "limited combustible." Included in this class are the modern supermarkets, shopping centers, and warehouses.

  • Class 3-Ordinary/brick and joist refers to a structure that has exterior walls constructed of noncombustible materials such as brick, concrete block, or clay tile and interior floors, walls, and roof members constructed of wood. These types of buildings include older multiple dwellings, brownstones, and mixed occupancy structures.

  • Class 4-Heavy timber, also referred to as "mill construction," has exterior walls of brick, stone, or block, and interior floors, columns, and girders made of large wooden interior timbers. Wooden columns are generally no less than 8 inches by 8 inches in thickness, floor and roof girders will be no less than 6 inches by 10 inches, and floor planking will average around 3 inches by 12 inches. They are very large and inherently strong buildings.

  • Class 5-Wood frame refers to a building built primarily of wood. Although the method of framing within these types of buildings has changed over the years, it has wooden walls, floors, and roof supporting members. This type of construction generally includes private dwellings.

  • Hybrid construction has elements made of lightweight or pre-engineered materials that may be mixed within or may have replaced any of the previous classes of construction or materials identified. Examples of these materials include lightweight wood trusses, unprotected steel, and wooden I-beams, to name a few. This category of materials necessitates that we continually rethink our strategy and operating times.


When attempting to gather information within your occupancy size-up, you should be looking in more than one specific area.

  • Occupancy classification. This is what many of us will initially consider when we are referencing the building's occupancy. Identifying the building as residential, commercial, or health care, to name a few, begins to lend information regarding our concerns with the building's life hazard.

  • Occupancy content. The occupancy of the building can also identify specific information regarding the building's content/storage. The fire officer should consider during a preplan size-up or an "on-the-scene" size-up the following: Are hazardous materials in the building? What is the building's fire load? Are there any specific stock concerns in the building that may affect or alter the decisions made? Example areas might include the following: plumbing supply warehouses-increased collapse potential; carpet and rug stores-hydrogen cyanide gas from content involvement; baled paper/cardboard warehouse-swelling stock that could push out walls; and museums, jewelry, camera, and computer stores-high-dollar-value content.

  • Occupancy/construction associations. We know that certain occupancies will require large open areas simply because of the nature of their business. Structures that house supermarkets, auto dealerships, furniture showrooms, bowling alleys, and movie theaters will all require large open areas for their business needs. These types of occupancies should indicate to the firefighters and fire officer that the building will contain some type of truss roof assembly and may also have a truss floor assembly.

Apparatus and Staffing

This size-up factor represents another category that can lend more than one piece of valuable information.

  • Staffing. This continues to be one of the most controversial issues plaguing today's fire service. Understaffing fire departments is a dangerous practice that simply does not work. It is critical in this size-up category for officers to identify and factor in their resource levels. Knowing the staffing limitations on each apparatus and the total complement of officers and firefighters responding on the initial alarm assignment will indicate what can and cannot be done efficiently, effectively, and safely.

  • Response complement and capabilities. Attention is directed to the number and type of apparatus responding and their capabilities. As an example, an engine company responding to your incident capable of delivering 1,000 gpm of water is very different from an engine company capable of delivering 2,000 gpm of water. This is specific information you would want to know, especially if you're looking to assign one of those two engine companies to a water source at an incident.

Expanding on this idea of resource typing, in Jersey City all of the city's fleet of aerial and tower ladder companies were once all referenced as truck companies. The department decided a number of years ago to resource-type its fleet to aid the chief officers in sizing up apparatus. As an example, if a department alarm printout sheet shows that Ladder Co.12 and Tower Ladder Co. 4 were assigned on a response, the responding battalion chief would immediately know what his responding ladder company capabilities were going to be. If, on the other hand, the chief read that Ladder Co.12 and Ladder Co. 4 were responding to the incident, he would know, based on the resource-typing policy used within the department, that Ladder Company 4, normally a tower ladder company, must be used as a spare/reserve aerial ladder. This identification change would immediately tell the officer that no tower ladder apparatus is responding to the incident; therefore, he would need to specifically request one if he wanted one-a simple but effective method to deliver specific information.

Life Hazard

The IC must consider four distinct groups of individuals within the life-hazard profile.

  • Firefighters. In my opinion, this group is the first the IC must consider and be responsible for. Decisions on the fireground have to focus on ensuring their safety. From the proper number of individuals to accomplish a task to disciplined operating modes, decisions have to be centered around making sure everyone gets home at the end of the shift.

  • Occupants. These are individuals in the fire building and any threatened exposures. Experienced and educated decision making is a definite prerequisite here. Factors that must be immediately considered include the building's class of construction, the location of the fire within the building, the number of occupants within the building, the occupants' locations in relation to the fires, and the deployment and assignment of resources to search and remove them.

  • Bystanders. This category would encompass anyone near the fireground perimeter. People who often fall in this category would include spectators or curious onlookers, the media, and fire photographers or fire buffs.

  • Other emergency service personnel. This group includes those who are members of other agencies or who are operating in or near the fireground perimeter. Examples include the police department, emergency medical services, hazardous materials teams, and utility companies.


This size-up factor refers to the topography and obstructions that might interfere with, delay, or cause concerns related to fire department operations.

  • Setbacks. Buildings built back from a street or accessible area. The immediate concerns here are apparatus placement and operation.

  • Buildings built on grade. Structures that are two stories on the A side and four stories on the D side will cause serious management difficulties if you do not plan for them.

  • General accessibility. Consider obstructions such as fences, trees, and overhead wires-all of which can cause delays and operational concerns on the fireground.

Water Supply

Fire officers and firefighters attempting to gather information on water supply will have to look for information that is specific to the resources available in their own town or city. Some departments may have to rely on natural sources such as rivers, lakes, or streams, whereas others may have hydrants spaced every 300 feet. When referencing the flows needed to extinguish the fire, however, the considerations narrow to focusing on the following: the fire building's class of construction; the location, extent, and amount of fire; the building's contents/fire load; the building's height and area; and the proximity of the exposure buildings, taking note of their class of construction, fire loading, and height and area.

Auxiliary Appliances and Aides

Review the devices, equipment, and people that could aid you in your efforts. When any information in this size-up category is available at a particular building or complex, the fire department should identify and review it well before receiving an alarm. The resources can range from detection devices and suppression equipment to on-site personnel educated and trained to assist the fire department. You must know when these resources are present and their most efficient uses and use them whenever possible.

  • Fire detection equipment. Numerous designs and types of detection devices may be installed in a building. Equipment designed to detect the products of combustion will do so by sensing smoke, heat, or flame. Noting their types and presence within a building may lend information to specific content concerns.

  • Fire suppression equipment. Equipment designed to aid in suppression efforts will generally fall into three types of systems: sprinkler, standpipe, and special extinguishing. Having preincident information about the system present greatly enhances the fire department's ability to use the system in an efficient, effective, and safe manner. Attempt to gather information relating to the type of system, the area(s) of the building served, the location of fire department connections, the zones served by the fire department connections, the location of control valves, and augmented systems.

  • Aides/assistants. Consider individuals who can provide information or assistance at a specific incident as a valuable resource and as potential auxiliary aides. Know who these individuals are well before the alarm is received or, at the very least, immediately on arrival; these individuals might include a safety plant manager at a chemical manufacturing facility, a building engineer at a commercial office high-rise fire, and an on-site fire brigade or hazardous-materials response team that could assist with extinguishment or product control. Remember that we are not the initial on-scene experts at every incident to which we respond. When available, seek out these individuals.

Street Conditions

Firefighters and fire officers should identify those areas that could affect apparatus movement and placement and the eventual operation. Conditions specific to this factor likely will vary from city to city and town to town. However, it seems that the older the community, the greater the awareness.

  • Street width. In many older areas of our country, fire departments are forced to drive their apparatus down street widths originally designed to accommodate the horse and buggy. Narrow car-lined streets can delay, restrict, or even eliminate key apparatus placement. Officers and firefighters must identify the streets that present these concerns.

  • Traffic flow. Two-way traffic in many older cities is a luxury that seems to be restricted mostly to major thoroughfares. For many, streets that run perpendicular to these main arteries of traffic are identified as one-way streets that are often narrow and long. Many departments confronted with these types of conditions deem it critical that the initial responding units (first-due engine and ladder) proceed into the street with the flow of traffic. The obvious concern is to eliminate apparatus coming in blindly from two directions, possibly pinning civilian vehicles in the middle of the block, even in front of the fire building. Ignoring or being complacent about this particular size-up factor will guarantee eventual confusion and a crucial delay in your operations. If you don't have a policy for initial response into one-way streets, you should develop one.


Weather size-up refers to those elements that can affect fire department response and operations. Factors to consider include the following:

  • Wind. It continues to cause great difficulties for firefighters operating at any type of fire. Wind as little as 10-plus miles per hour should be considered significant and be factored into the officer's decision making. Whether fighting a brush fire in the middle of an open field or a structure fire in the inner city, the wind will seriously affect fire department operations and firefighter safety.

  • Temperature. When temperatures begin to climb or fall, ICs have to observe the effects on operating forces and the fireground. Temperatures that fall below 40F or climb above 85F should influence the officer's decisions with regard to scheduling early and frequent firefighter relief and rehabilitation periods. Considerations of heat exhaustion and heat stroke to hypothermia and complete exhaustion should prompt ICs to call for additional alarms to replenish forces if necessary.

  • Humidity. During high-humidity periods, officers must be concerned with early and frequent relief for firefighters. High humidity also can affect ventilation efforts, making it more difficult to remove smoke and find the fire. On the other end of the spectrum, low humidity presents an increased concern about fire spread. Low-humidity atmospheres produce lower moisture contents and dryer combustibles. Combustibles, once ignited, will allow fire to spread at an accelerated rate of speed.

  • Precipitation. Officers must anticipate extended response times and slowed operations when heavy snow, rain, or fog is present.


Exterior exposures are a major concern for many fire departments. Congested urban and suburban areas are literally forced to deal with buildings built right alongside the other. When buildings are attached to each other or separated by only a few feet, you must consider fire extension into adjoining or nearby structures early in the operation. In these types of settings, when you hesitate, you might allow the fire to occupy not only one building but three buildings in a short time.

(4) Exposure buildings will present an immediate concern not only from their proximity but also from their exterior sheathing. (Photo by Chris Fink, Jersey City EMS.)

(5) Firefighters assigned to the roof can quickly identify a building extension in the rear of an attached row of buildings.

For incident commanders to direct efficient and effective fireground operations, officers must identify and prioritize the need to protect exposure buildings from a number of factors, including the following:

  • The life hazard. Prioritize buildings on the basis of which is "the most severely threatened exposure building" vs. "the most threatened life exposure building." There is a difference.

  • The location and extent of fire. What is the current fire involvement? What is the probability and possibility of extension?

  • Exposure proximity. Is it attached or separated? By how much?

  • Influencing factors. These include exterior sheathing, light, and airshafts between buildings, common cocklofts, cornices, and so on.

  • Wind. Consider its speed and direction.


The term "area" is defined as the square footage involved as well as the square footage threatened by fire. By definition, this size-up factor will assist in determining the maximum potential fire area with which the incident commander might have to contend. When responding to any type of building, it becomes extremely beneficial to have information about the layout, configuration, and square footage of the area in which you may have to operate. Getting a look at the building prior to its being full of smoke and heat will help quell fear about crawling into the unknown; it will also help the incident commander anticipate strategic and tactical needs.

(6) Top floor/cockloft fires will present difficulties with accessibility and rapid fire spread. (Photo by the late Joe Lovero, Jersey City Fire Department Communications.)

Without preincident information, the IC must rely on information gathered and relayed by interior and exterior crews. Information about interior floor layouts, square footages, or irregularly shaped areas will take time to gather and report. Exterior observations and the information that can be gathered and relayed can come much faster if it is sought early. Members from the ladder company that establish the roof position can provide a list of valuable observations from their vantage point. Among those specific pieces of information should be the building's layout and square footage.

Location and Extent of Fire

This size-up factor is defined as the location of fire within the building, combined with the fire's extension probabilities and possibilities. The fire's location and degree of extension in the building are the most influential factors in the fire officer's size-up. This is the information that will enable the officer to determine the severity of the occupant life hazard, the resources required for deployment, and the strategy and tactics associated with the operation.

Following is a list of areas within a building and the ways they influence decision making: belowgrade fires-basements, cellars, and subcellars; lower-level fires-areas immediately abovegrade; top floor, attic, and cockloft fires-as listed; upper-level fires-those areas out of the reach of fire department ladders and hose streams. Each of these four locations presents specific thoughts that every firefighter and fire officer must be able to identify and factor into the size-up.


This factor in our fireground size-up refers to the specific time of the day, the day of the week, the time of the year, the burn time of the incident, and all of their influencing factors. The time of the day and the time of the year are generally the first two factors that come to mind in this size-up category. Referencing awake or sleeping building occupants, area traffic patterns, shopping center fire loading, as well shopping center occupant loads are just some of the items that can be identified and factored within this category.

I'm sure all ICs would desperately want to be able to factor in the burn time of an incident. Attempting to determine burn time is difficult and sometimes dangerous. In years past, fire service reference materials gave specific time frames within which firefighters could operate in a building before it was expected to collapse. Today, it is unrealistic and dangerous to attempt to set a specific time frame within which a building may collapse. Many variables must force us away from this kind of thinking. Varied response times, lightweight construction, and building alterations are just a few of those items. Your knowledge, experience, and education with reference to the specific building and its construction features are your best indicators of the time within which you can safely operate in the structure.


The fireground commander should use the building's height and square footage to determine the building's maximum potential fire area. When fires occur on the upper levels in tall buildings, firefighters are forced to take the fight entirely inside. This means that accessibility and how to get up to the upper floors quickly and as safely as possible must be considered initially. Ventilation of the fire building will be restricted because of the limited number of openings or possibly by the building's ventilation system. Smoke will behave differently in tall structures than in smaller, lower-level structures primarily because it is restricted within the space and is influenced by building and atmospheric temperature differentials.

The structure's height is a significant factor for the officer attempting to determine the fire's location, accessibility to the fire floor and floors above, and the behavior of smoke within the building.

Special Considerations

Here, you can combine any number of the previous factors in an attempt to develop sensory cues to assist with your strategic and tactical decision making. Your education and experience with the size-up factors will allow you to formulate a thought, a concern, and then an action to protect your firefighters and control the incident. Some examples may include the nature of the incident-for example, whether it is a late-night or early-morning fire in a fortified strip mall or taxpayer; size-up factors-time, construction, occupancy, fire loading, fire extent, life hazard, apparatus, and staffing; and concern-a fire that can produce backdrafts or advanced fire conditions if not recognized and planned for.

Size-up is the foundation of the fire officer's decision making. By gathering the information before, during, and after an incident, you will acquire a wealth of information you can use. The key is to begin the process as soon as possible.

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