The Initial Size-Up

Sizing up of the situation makes an initial defensive attack or a change of tactics from an offensive to a defensive operation justified.


The last two critical size-up factors that must be recognized upon arrival are occupancy and life hazard. These again are inter-related to each other. For example; is the fire building residential or commercial? If it is residential we can expect that there may be persons inside that need to searched for because they are unable to help themselves. Persons sleeping in bed may not know there is a fire because they are not conscious to begin with.

Although this idea of search and rescue for sleeping persons in a residence at 2 a.m. is not a new idea to the fire service, the size-up of the occupancy prior to entering is beneficial and should be considered. For example is the building a two-unit apartment building or is it a single-family residence? With each of these occupancies where will the bedrooms be located? A single-family house will have all or most of the bedrooms grouped together whereas a two-unit apartment building will have two sets of bedrooms because there are two separate living units inside.

Also with the above occupancy examples, how does this change the primary and secondary egress for searching firefighters? Where will the secondary door be if we cannot drag a civilian back the same way we came in? To ensure our safety, a good understanding of the occupancy will help us determine where the exits of a single-family or a two-unit apartment building would be prior to entry.

Commercial Structures
Commercial occupancies will differ significantly from a residential occupancy concerning life hazard. This is because, in a residence we can expect to perform search and rescue, but in a commercial building fire it can be expected that most or all of the victims will run out (if they can move on their own). The reason for this is that no one is sleeping when the fire started. Commercial occupancies are usually places of business. All the occupants have to do is find out about the fire and they will leave.

So the question on commercial occupancies for firefighter safety is this; do we search a commercial occupancy like we search a residence? Of course the answer is no, but some of the justification for firefighter injuries and deaths in commercial occupancies by the local fire department's media affairs person sounds like this; "We didn't know if everyone was out so we went in". This is certainly not good enough to protect our members and may just be a case of little or no size-up training for first and second due fire companies.

The big thing to remember when we arrive on the scene of any fire emergency is to perform a size-up. This is if you are the first-due company to the scene or you are assigned the task of rescuing injured firefighters. A good size-up consists of at least four factors. They are Construction, Occupancy, Life Hazard along with Location and Extent of the Fire. There may be additional factors for different situations to consider as well. There may be questions to answer like, "What is the manpower on the scene?", "What are weather conditions?", "Where is a good water supply?", "How are street conditions?", "Are there any hazardous materials?", etc. All of these answers will also help ensure the safety and effectiveness of your crew.

The vast majority of the information that you will collect and that will keep you alive while performing an interior operation will be gathered outside the fire building before you enter. The reason for this is when a firefighter gets inside there is an inherent "tunnel vision" because all they can usually see is smoke on the outside of the SCBA mask. That may not be enough information to survive as the situation rapidly deteriorates around you if you don't size-up before entering.


Jim Mason has over 20 years in the fire service and serves as a lieutenant with the Chicago Fire Department. As a firefighter he has been assigned to engines, trucks and heavy rescue squads. He is a lecturer on fireground operations and is currently serving on a International Association of Fire Fighters committee to help develop a firefighter self-survival program.