The simple recognition of construction hazards, fire development and scene awareness are key in a successful firefight.

The size-up of a fire building upon arrival is a critical, self-survival technique that must be completed prior to entering the smoke and heat of any interior operation. In the days when there were many fires that would develop a firefighter's experience level we could learn through "on the job " training so it was not necessary to train on size-up. But today, with the lower levels of experience and the explosion of quick-collapse, lightweight truss-constructed buildings, firefighters must train on size-up to survive on the fireground.

Size-up can be broken into four major factors: Construction, Occupancy, Life Hazard along with Location and Extent of the Fire. These factors are critical to understand prior to making any decisions to act on the fireground. They are also inter-related to each other. For example, upon arrival to the fire scene, we cannot get the big picture of the construction style of the fire building without also considering the location and extent of the fire. What is the construction style and where is the fire? What damage has been done to the building prior to our arrival to the scene and what damage is going to be done in the next few minutes? In other words, to understand these two related size-up factors we need to use our fireground experience and book smarts to recognize the current situation and predict what will happen next.

Many times in the distant past, as well as this year, the fire service has seen multiple firefighter deaths and injuries, which could be attributed to the lack of a good size-up. A study of these incidents is likely to reveal a poor assessment done upon arrival and continuing throughout the incident. With the study of past fires such as these we should expect that these types of incidents would stop, but with all the duties that have been given to the fire service in recent years one thing that may have been lost in our training schedules is the size-up drill for fireground survival.

Simply recognizing a deadly situation such as a truss constructed roof or floor assembly that is exposed to fire and then performing a defensive attack will often be enough to bring everyone home. Sizing up of the situation makes an initial defensive attack or a change of tactics from an offensive to a defensive operation justified. Often a change of tactics is brought about by reports made by firefighters on the scene that the incident commander (IC) would not normally be expected to have knowledge of like roof conditions.