July-August 2009 Issue

	July-August 2009

Reading Smoke, Part 5

By John Mittendorf

Once the six sides and the attic area have been quickly evaluated, consider the four primary extension routes of fire and smoke as follows:

FOUR PRIMARY EXTENSION ROUTES

Basements

Basement fires are potentially one of the most dangerous fires that fireground personnel will encounter as this type of fire continues to claim firefighter lives each year.

Some of the hazards of a basement fire are below grade (minimal access and egress options), often contain a high fire load (storage of various materials), and personnel standing on the grade floor above the basement are in reality standing on the roof of the fire. If smoke is visible from a basement area, the following hazards should immediately be anticipated:

The normal extension route for fire and smoke is vertically through those portions of the structure above the basement. Pipe alleys, balloon frame construction, and other similar avenues enhance the upward spread of fire and its byproducts.
Basement fires can be difficult to ventilate, depending on the number of windows-doors that are common to the basement area.
When attack personnel advance a line into a basement, the open door will enhance the travel of oxygen to the fire. Therefore, expect the fire to become more intense.

Single-Story

Fires in single-story structures can be relatively straightforward, due to the facts that access and egress of personnel is simplified compared to other types of buildings, floor plans can be straightforward, particularly in dwellings, and extension routes are limited (depending on the size of the structure). If smoke is visible from a single-story structure, evaluate the following conditions:

First, read the attic vents to determine the possible extension to the roof structural members. Remember, the only barrier to an interior fire extending to an attic area is the ceiling material. In dwellings, this is normally comprised of ½-inch drywall and dropped or hung ceilings in commercials. Both of these materials are not a substantial barrier to fire.
If fire has extended to an attic area, initial personnel should pull the ceiling (before entering the structure) and extinguish any visible overhead fire. Always keep a fire in front of advancing personnel. Never let fire get behind advancing personnel and be able to block the entry-exit opening. Remember that fire can enter an attic as a result of lapping from a window into exposed attic vents.
Ventilation (horizontal, vertical, PPV) can often be rapidly implemented.
Remember that single-story structures come in a wide variety of sizes, as there is a significant difference between a 1,700 square-foot dwelling and a 50,000 square-foot concrete tilt-up commercial.

Multiple-Story — First Floor

Fires on the first floor of a multiple-story building are also similar to fires in single story structures in that they can be easy to enter and exit, and the space between the first and second floor is minimal and normally of heavier construction (ceiling joists) than attics. In many cases, the flooring between the first and second floor provides a barrier to the rapid extension of fire (compared to ½-inch drywall). However, smoke can extend to upper floors but is dependent on the presence of vertical voids and passageways from the first floor to upper floors. Normally, ventilation is limited to horizontal and PPV.

Multiple-Story — Top Floor

Once a fire is located above ground, the inherent hazards are dependent upon several key factors:

What is the distance from the ground to the fire? Is the fire on the second floor or the 30th floor? This will have a direct impact on the time it takes personnel to reach the fire. Remember a basic fireground rule for fires above ground is: "Equipment on the apparatus in the street is unusable inside the structure, and may not be easy to retrieve."
If the fire is on the top floor, then the only barrier between the fire and the attic is the ceiling material. Remember to read the attic vents (if present).
Horizontal ventilation may be more difficult until personnel reach the fire floor. In some cases, vertical ventilation and/or PPV is a superior method.

In our next article we will look at reading smoke from an exterior perspective.

Chief Mittendorf is the author of “Truck Company Operations” and “Facing the Promotional Interview”. To purchase, return to the Main page and scroll down to Fire Nuggets Books and Videos.

<•••SIGN OUT

RETURN TO CURRENT ISSUE INDEX