Establishing Collapse Zones At Building Fires

In most fireground situations involving a structure fire, the probability of and anticipation for structural collapse or compromise are inevitably minimized, overlooked or at times disregarded until the catastrophic conditions present themselves with little to no time to react accordingly. The loss of situational awareness coupled with distracted attention to subtle or obvious pre-collapse building indicators and gaps in building and construction system knowledge combine to elevate operational risks to personnel on the fireground at structure fires.

Each year, a sizable percentage of the number of firefighters killed is the result of structural collapse. There are cases on record where the deaths from collapse were a direct result of faulty size-up by officers because of their lack of knowledge of building construction, fire behavior and rate of water application needed.

Sounds recognizably like a preamble to any number of current reports or position statements relevant to today’s prevailing issues or conflicts affecting the Fire Service. In fact, it was written by Chief Lloyd Laymen, circa 1951, in his groundbreaking book Firefighting Tactics. Some things have withstood the test of time, regardless of progress, yet are diametrically influenced by the built environment, its buildings and the fires we fire within. Stretching into a building about which you have no knowledge, insights or considerations is derelict, placing you and your company at risk. Where do you fit in to these types of operations?

Building performance

Today’s evolving fireground demands a greater understanding of buildings, occupancy risk profiling (ORP) and building anatomy by all companies operating. The identification, assessment, probability, predictability and intrinsic characteristics of building performance under fire conditions must not only be comprehended, but postulated into an adaptive fire-management model with flexible and fluid incident operational parameters.

The potential for structural collapse in a building on fire can be predicted by a building’s inherent susceptibility to a variety of factors that include fire dynamics and behavior, fire exposure and extension, environmental impact, fire suppression activities and age, deterioration and occupancy use factors. The predictability of a building’s performance and risk to structural collapse, compromise or failure must be foremost in the development and execution of incident action plans (IAP) with collapse precursors or indicators identified, monitored and managed by incident commanders, supervisors and operating companies.

Understanding a building’s design and structural anatomy, construction methods and materials and vulnerabilities under fireground conditions has a direct correlation to safe firefighting operations and firefighter survivability. If you understand the building’s structural system, integration of materials and construction methodology and their impact from fire, an effective IAP can be developed and the management of the fireground can be controlled through collapse zones and operational exclusion areas.

Inherent building characteristics prevalent in buildings of Type III (ordinary) or Type IV (heavy timber) construction present the risks for masonry perimeter wall collapse, as well as internal floor collapses, whereas buildings of Type V (wood frame) construction may be affected by compromised wall-floor or wall-roof interconnections or from the collapse of architectural features and components such as a chimney, porch or attached canopy. Type I (fire resistive) and Type II (non-combustible) construction may have parapets, suspended signage or large span lintel or beam openings that affect the integrity of the building envelope.

Community Risk Assessments, when coupled with a pre-fire planning program, can provide pre-incident insights to the organization, incident managers and officers for occupancy risk, inherent collapse probability and projected operational demands associated with fire based incident conditions. Building age, vintage, environmental impacts, occupancy use or neglect all contribute towards understanding risk from collapse, their management and operational demands.

A review of historical records or data may also provide insights on frequency, severity and susceptibility as well as operational, resource or training gaps that may need greater attention or corrective actions. An integrated Community Risk Program and a proactive pre-fire program that periodically and systematically assesses the community’s built environment, its buildings, occupancies, use, status and incurred changes, alterations and adaptive reuse is a vital tool in fire safety and prevention. Understanding your community and the expected performance of its building can aid greatly in addressing fireground incident priorities and subsequent structural collapse events.

Between the reporting period of 2000 and 2012, some 1,230 U.S. firefighters died in the line of duty. Incident reporting data compiled by the U.S. Fire Administration (USFA) identified that structural collapse caused 142 (or 11.5%) of these deaths. Structural collapses often resulted in multiple firefighter injuries and fatalities. The number of fatalities includes firefighters killed by collapse conditions both inside a structure (interior compartment collapse) and outside a structure (perimeter collapse).

As I have stated previously: “In most fireground situations involving a structure fire, the probability of and anticipation for structural collapse or compromise are inevitably minimized, overlooked or at times disregarded until the catastrophic conditions present themselves with little to no time to react accordingly. The loss of situational awareness coupled with distracted attention to subtle or obvious pre-collapse building indicators and gaps in building and construction system knowledge combine to elevate operational risks to personnel on the fireground at structure fires.”

Types of collapses

Structural collapse or compromise can occur internal within a building or external commonly around its perimeter affecting a wide venue of the fireground. The fireground perimeter has a high degree of risk and vulnerability due to the primary building access and egress points, apparatus positioning, staged personnel and proximity of tactical operations related to the building envelope.

This places personnel in direct primary or secondary collapse prone areas that may be subject to collapse. The degree of collapse can be isolated or catastrophic in scope and severity and affect building components, assemblies or entire systems such as a perimeter wall, roof or architectural or construction features such as a canopy, parapet, window dormer or roof coping.

Key indicators and considerations for Roof (RF), Floor (FL), Perimeter wall (PW) or Building Feature (BF) collapse should be recognized, comprehended and acted upon in a timely manner. The presence of spreader plates, star or tie rod connections, or other structural reinforcement add-ons found on the exterior face of unreinforced masonry (URM) or reinforced masonry (RM) buildings of legacy construction (circa 1900-1949) or heritage construction (pre-circa 1900) exemplify inherent collapse prone building conditions.

Evidence of displaced brick or block coursing, cracks and separation of masonry joints, absence of masonry joints, out-of-plane or bulging walls and effloresce, degradation and deterioration of  the building envelope, connections and bearing and tie-in points are cause for concern for perimeter wall, cornice, facade or envelope integrity.

The presence of placards or signage on exterior building areas depicting the presence of engineered structural systems (ESS) or engineered truss construction components for FL or RF systems. The presence of these placards can provide first-arriving fire companies with key building information. When coupled with fireground size-up and risk assessment, they can support an accurate determination on tactical intervention and prompt collapse zone considerations.

The building’s structural system and construction and materials will influence the type of structural collapse encountered, the scope and severity of the collapse and the magnitude and extent of the collapse zones. Varying building types and occupancies have common as well as unique structural collapse profiles that affect that manner in which a perimeter wall, architectural feature or assembly may collapse and the monolithic or segmental extent of the collapse on the fireground.

Although perimeter wall and floor collapses have frequently contributed to firefighter line-of-duty deaths and injuries, numerous firefighters have been killed as a result of a chimney, cornice, canopy, coping block or marquee collapse. Maintaining heightened situational awareness on the operating scene, knowing what to look for and comprehending what it is you are seeing relative to collapse indicators or risk are key attributes for preventing death and injury.

Collapse zones

The timely establishment and delineation of collapse zone (s) and their management is imperative for firefighter safety and operational continuity. The incident commander and assigned division/group supervisors, safety officers and company officers must be highly cognizant of and establish collapse zones appropriate for a building’s occupancy risks, construction systems and fireground conditions, both in the immediate operational period as well as the incident’s progression into extended operations, when the building can become highly susceptible to failure or collapse due to the effects of the fire and loss of structural integrity, resistance, or distribution of structural loads.

• A collapse zone is defined as the area around the perimeter of a structure that could contain debris if the building collapsed. This area is often defined by establishing a perimeter at a distance from the building that is equal to 1.5 times the height of the structure.

Projection of or anticipation for a structural collapse must be identified as early in a progressing incident as possible. Proactive apparatus placement and positioning while anticipating the potential of degrading building conditions and the need for collapse zones, helps prevent the introduction of personnel into high risk divisional areas that are prone to or are experiencing collapse and compromise of components or systems due to time delayed identification or slow reaction to collapse indicators or collapse progression. 

In buildings of Type III (URM or RM) or Type IV construction, including mill and semi-mill construction, incident command must be highly focused to the high probability of internal and external collapse, establish and control collapse zones in multiple divisions and possible exposure properties and expect collapse to occur.

All personnel should maintain a heightened state of situational awareness and survey the building periodically during all stages of fire suppression with increased diligence during salvage, overhaul and post fire suppression phases due to degraded and compromised structural systems, assemblies and building components. The post-fire suppression phase of operations is a high-risk/high-frequency collapse prone operation period that requires incisive monitoring of building conditions, further expansion of collapse and exclusion zones and conscientious tactical activities that do not place personnel in unsafe conditions.

Additional references:

1. National Institute of Occupational Safety and Health, Death in the Line of Duty: Career lieutenant and fire fighter killed and two fire fighters injured by wall collapse at a large commercial structure fire – Pennsylvania. F2012-13 (2012)

2. Occupancy Profiling and Buildings on Fire Risk Assessment Matrix, Buildingsonfire.com additional information can be accessed at http://buildingsonfire.com/buildings-on-fire-risk-assessment-matrix

3. Naum, C. “Predictability of Performance of Buildings on Fire,” Firehouse® Magazine, June 2012

4. Naum, C. “Building Anatomy: Types and Classifications,” Firehouse® Magazine, July 2012

5. Naum, C. “Reading the Building: The Importance of the Size-Up,” Firehouse® Magazine, April 2013

6. Naum, C. “Building Construction for Today’s Fire Service,” Firehouse® Magazine, January 2015

7. Naum, C. “Today’s Buildings: What Happens When They Burn,” Firehouse® Magazine, February 2015

CHRISTOPHER J. NAUM, SFPE is a 39-year fire service veteran and national instructor, author and lecturer. He is an authority on building construction issues affecting the fire and emergency services and a former fire command officer, architect and fire protection engineer. Naum is a technical consultant to the NIOSH Firefighter Fatality Investigation and Prevention Program, a NFFF Firefighter Safety Advocate and served on the Board of Directors of the ISFSI and the IAFC Safety, Health & Survival section and faculty at the National Fire Academy. He is the executive producer of Buildingsonfire.com, a site dedicated to building construction, adaptive fire command and firefighter safety.