VOL 3, ISSUE 7     July 2002

Rules of Engagement, Thermal Imaging Tip of the Hat, and bits and pieces from here and there are included in this issue of the Safety Gram.

10 Rules of Engagement for Structural Fire Fighting

Originally published through the IAFC, this document has been out for a number of years and provides a good explanation of ‘Risk Assessment’.  The text has been edited.

All fire fighting and rescue operations involve an inherent level of risk to response personnel.  And a certain minimal level of risk is recognized and accepted, in a measured and controlled manner, in the efforts routinely employed to save lives and property.  These risks are not acceptable in situations where there is not potential to save lives or property.

A higher level of risk is acceptable only in situations where there is a realistic potential to save known endangered lives.  This higher acceptance of risk must be limited to situations and operations that are specifically directed toward rescue where there is a realistic potential to save person(s) known to be in danger.

The exposure of fire fighters to an increased level of risk is acceptable only in situations where there is a realistic potential to save known endangered lives.

            No property is worth the life of a fire fighter.

No risk to the safety of fire fighters is acceptable in situations where there is no possibility to save lives or property.

Fire fighters shall not be committed to interior offensive fire fighting operations in abandoned or derelict buildings that are known or reasonably believed to be unoccupied.

It is the responsibility of the incident commander to evaluate the level of risk in every situation.  This risk evaluation shall include the assessment of the presence, survivability and potential to rescue occupants.  When there is no potential to save lives, firefighters shall not be committed to operations that present an elevated level of risk.

An incident command system shall be established, beginning with the arrival of the first fire department member at the scene of every incident.  The incident commander must conduct an initial risk analysis to consider the risk to fire fighters in order to determine the strategy and tactics that will be employed.

The responsibility for risk assessment is a continuous process for the entire duration of the incident.  The incident commander shall continually re-evaluate conditions to determine if the level of risk has changed and a change in strategy or tactics is necessary.  The incident commander shall assign one or more safety officers to monitor and evaluate conditions to support this risk analysis.

            At a minimum the risk analysis for a structure fire shall consider:

                        Building Characteristics

-          construction type and size

-          structural condition

-          occupancy and contents

Fire Factors

-          location and extent of the fire

-          estimated time of involvement

-          What are smoke conditions are telling us?

Risk to Building Occupants

-          known or probable occupants

-          occupant survival assessment

Fire Fighting Capabilities

-          available resources

-          operational capabilities and limitation

Roof Notes: Observations on Fire

The other day we encountered a serious fire underneath an open web, wood and metal truss.  A number of issues came up in relation to this fire that are worthy of note.

1. Upon the discovery that the structural components included a large area of metal and wood trusses and that some of those trusses had failed, the building was evacuated and interior fire fighting operations ended.

This is a bad sign.

2.       Prior to the discovery of the truss system, a team was placed upon the roof.  Their purpose for going to the roof was to look for loading hazards, like an HVAC system.  They observed only that the roof was shrouded in smoke and did not notice any other problems with the roof.  They did not know that the roof system in that portion of the building was supported on wood and metal trusses.  It is important that ventilation crews sent to the roof make inspection cuts to ascertain the layout, composition and direction of roof components as well as to assess the progress of the fire.  Initial cuts should be made at the point of departure onto the roof and at regular intervals along the path of travel. Regular inspection holes will give the vent crew indications of the progress of fire beneath the deck.  This sort of information is an important part of building assessment and should be provided to the IC as soon as possible.  When there is a need to obtain reconnaissance of a suspected lightweight roof and there is active fire beneath it, consideration should be given to the use of ladders or aerial devices for the elevated perspective. 

3.       Other clues and indicators may be present and should be included in an assessment of roof stability.   Flame and smoke issuing from roof vents and pipes will provide a good indication of fire progression under the deck.  Sagging roof systems and open flame above the surface of the roof should raise alarms in the mind of the Officer leading the vent team.  This information must be relayed to the IC so that he/she can perform continual risk assessment.

4.   Open web, wood and metal trusses are anchored to the wall on the top chord of the truss.

            They are designed to cover long spans between supporting members.  Therefore, when you are sounding the roof you may only be able to detect the trusses themselves.  That is different from a lightweight panelized roof where there are both purlins and rafters.  If you encounter a roof deck that provides sounding indications of regularly spaced structural support without indication of cross bracing, you may be on top of an open web truss.   With any kind of fire beneath you, you and your crew are in danger. 

5.  Trusses will typically fail as a unit.  This collapse will bring down the roof deck on either side of

            a truss.  Expect that the failure will include the roof on either side of the truss and include the trusses full length.  The problem arises in that these systems do not typically fail as a single truss.  In a fire, the exposure of one truss means that other trusses are being destroyed too.  The failure of a single truss will precipitate a general collapse of many trusses and could cause the entire roof system to fail.  Ventilation operations above a fire where the roof is supported by trusses is one to avoid.  Remember that it will do no good to walk the edge of the roof to avoid being dropped into the hole created by a collapse because the truss is directly anchored to the wall and will fail in a manner that will bring about total collapse.

Indication of truss failure evident in sagging roof structure.

Heat and fire damage evident at roof vents.

Thermal Imaging Tip of the Hat: Fires Above and Below

As time goes by and the use of thermal imaging technology becomes more habitual more anecdotal stories come out.   Here are two.

Not so long ago a Fire Department responded to a fire in a row of stores in lightweight construction.  When they arrived on the scene, they were unable to ascertain the location and extent of the fire due to the fact that it remained hidden in the void above the ceiling.  All they were able to see was large volumes of black and gray smoke.  It was certain that they had a working fire, the question they needed to answer was where. 

A thermal imaging device was used to scan the ceiling spaces.  The image that they saw indicated that the fire was much larger than they had originally thought.

Due to the extent of the fire and the fact that the building had lightweight components, the Incident Commander called for a general withdrawal from the structure. 

The roof of the structure came in shortly after that with out endangering the crews working at the fire. 

The second story involves a fire inside of a dwelling.  When the Engine Company arrived at the front of this residence they were faced with situation of zero visibility due to smoke.   While making entry into the back of the house, they were able to pick up an image on their thermal imaging device that indicated that there was a hole in the kitchen floor.  They exited the building and made their attack on the fire from a different access point. 

The last anecdote comes from the great state of South Carolina where a fire department was engaged in suppressing a fire in a commercial building. The crews advanced into the structure were able to see the extent of the fire above them with their thermal imaging device.  As they fought the fire, the Fire Officer was able to detect (with the imaging device) the fact that the fire had extended over and past them and appeared to grow in intensity despite their efforts.   With indications that their escape from the structure was being compromised, they retreated.  Within minutes of withdrawal, the entire roof structure collapsed. 

The crews credit the use of the thermal imaging device with their timely withdrawal.  

Just some food for thought.  How often and under what circumstances do you apply your thermal imaging camera?