What Are We Getting Ourselves Into?

 
Impacts of Modern Building Techniques on Firefighting Efficiency, Effectiveness, and Safety

By Fire Protection Specialist Douglas Gordner & State Fire Administrator Bryant Stevens,
New York State Office of Fire Prevention and Control

Editor’s Note: In the fall of 2015, building upon the success of cooperative efforts to develop and implement the Firefighter Training – Best Practices, New York State Fire Administrator Bryant Stevens convened a meeting of the state’s largest fire service organizations with the goal of examining and planning for the future of the fire service. At the table are OFPC, NYSAFC, FASNY, AFDSNY, NYSFCA, and NYS PFFA. The goal of this group, which has been designated "Moving Forward," is to examine issues that the fire service is confronting in the 21st Century and provide information to fire departments and districts about the ways these issues can and may be addressed. One of the ways the Moving Forward group has chosen to do this is through a series of informative articles to be published in the various publications of these groups. The following article is part of this effort.

Unless you have been living in a cave, you know that they don’t build buildings like they used to. Modern construction techniques use less raw materials in their natural state and have greater dependence on pre-engineered, manufactured "systems" that often replace more traditional materials. This trend results in lighter weight materials being used.

While these construction techniques provide a number of benefits to the designer, contractor, and owner of the building, they provide the fire service with a number of critical concerns when there is a fire condition in these buildings.

We all realize that each building is unique; however, in many newer buildings, these modern day combustibles and construction techniques pose distinct hazards and changes in how the building "behaves" in fire conditions. A few of these include:
 
The average size of the single-family home has grown substantially in the last 50 years.
Fire loading has increased.
 Lightweight assemblies, whether protected or non-protected, fail significantly faster than "traditional" solid sawn assemblies because:
Traditional assemblies tend to fail locally (smaller portion), while the newer lightweight assemblies tend to fail globally. The majority of cases involve sudden failure over large areas with no warning.
Fire propagation and fire growth in residential fires has changed dramatically.
The combination of these changes – larger homes plus open floor plans plus increased fire loads plus ceiling, floor, and attic voids that are predominately made from lightweight components – equals faster fire propagation, shorter time to flashover, shorter escape times, and shorter time to structural collapse.

Many of our time tested methods of "reading the fire building" no longer apply in the newer lightweight construction. Examples include:
 Information from Underwriters Laboratories Testing

Recent tests by Underwriters Laboratories on lightweight building components have identified several concerns including:

Deflection times – Although a computer model predicted that the test floor assembly using engineered I-joists would retain its strength longer during a fire than the traditional wood platform, the opposite was the case. Furthermore, the engineered wood supports began to fail and deflect almost from the start of the test and proceeded to degrade in stages, leading to floor vibration, noise, collapse, and burn-through.

Charring – The rate at which engineered wood and traditional wood chars is similar. However, because of the very thin cross section of the I-beams, the report found that this charring rate poses immediate dangers to the mechanical integrity of the structure.

Heat sensitivity – Oriented strand board beam sections exhibited initial charring at a much lower temperature than traditional wood, making it impossible to further test some properties of the material.

Heat conduction – Due to compressed plies and binding material, the engineered samples conducted heat faster than other wood samples.

Brittleness – Engineered wood product samples exhibited increased brittleness and loss of mechanical strength compared with traditional wood components when heated in an oven, even without being exposed to fire. Researchers suggested this was due to separation of the constituent compressed fibers under mechanical and heat stress

Home furnishings –
Impact on the Fire Service

As one can imagine, all of these negative factors impact the fire department’s ability to operate efficiently, effectively, and safely. The three primary causes directly related to firefighter fatalities during interior operations at structure fires are:
Additional factors that result in a more rapid progression of fire with shorter time to flashover include:
 Firefighters and fire departments need to realize that unprotected lightweight wood assemblies can fail within six minutes of exposure to fire, while more traditional solid sawn dimensional lumber assemblies generally fail after 19 minutes of exposure to fire. Given the fact that many times these structural members have some type of inherent protection, such as sheetrock coverings that may give the fire department a few extra minutes, we no longer have the available time to mount a proper attack that we once had.

This illustrates that the game has changed in respect to this newer lightweight style construction and we, as firefighters and fire officers, need to adjust the game plan to accommodate these facts.

There are a number of things that fire departments can do to address these newer hazards, and some things that they can’t.

Improved building technologies, such as expanded use of fire sprinkler systems and other direct protection systems, will definitely impact fire spread and fire growth. However, the presence of these systems is not something individual fire departments have control of, as this is typically regulated at higher governmental levels.

What are the options for fire departments? Simply put, because our time to react has essentially been shortened, we need to:
So, in other words, we need to be more efficient and more effective in our fire attack. Let’s take a closer look at each of these factors.

Understanding These Hazards

Actions based on informed decisions always result in better outcomes, so the more we know about the fire building confronting us, the better our chances that this will be just another "routine" fire and not a tragedy. 

As firefighters, we need to know what’s in our districts. We need to get out and see how buildings are built. We need to know what type of assemblies and components are in buildings so we can then have a better understanding of how they will behave under fire conditions. The following are just a few of the building factors that are critical:
 We could go on and on with this list, but we hope you get the point. Knowledge is power and the more you know about a building, the better your control decisions and actions will be.

Earlier Arrival

These new buildings and new construction techniques tend to throw out principles that many of us have depended on when making fireground decisions. The standard time temperature curve is basically out the window. 

Buildings are going to flashover conditions much faster than before. In fact, flashover may have occurred prior to our arrival. While this is not beneficial from a fire control standpoint, at least it isn’t as hazardous to our firefighters as when the building is set to go to flashover shortly after our arrival or just as we begin an interior attack.

The point here is that if we are to achieve a quick knockdown before flashover happens, we need to generally improve response times. We need to evaluate our current operational construct and see how this can be accomplished. Long term, it may mean station relocations and other significant undertakings, but there may be things that can be done immediately that may not require a capital cash investment. 

Some options to explore include:
Closest unit response – District boundaries often predate development and, in many cases, the department responsible for fire protection is actually not the closest unit. It’s obvious that, given everything else being equal, the closest unit will get there first. Seems almost too simple, yet there are locations in New York state where the closet unit isn’t responding for a whole host of reasons. When a citizen’s home is on fire, the last thing he cares about is who pulls up in front of the fire building and what color the trucks are. All he wants is qualified personnel to get there quickly and extinguish the fire. If we truly put the people we protect first, then boundary disputes and which units should respond should be an easy fix.
Time "out the door" – Shortening the time period between alarm time and in route time provides us huge benefits when confronted with fires in buildings with these "newer" construction methods. If you are a volunteer house, has there been consideration of in station duty crews? Such a system allows immediate response, and the need to assemble a crew in those critical moments is removed. This can take a lot of different shapes and looks, and it can provide additional benefits beyond just response times. Career stations should also look at their "time out the door." While it is typically a very short period of time for them to be out the door, there may be ways that this time can be reduced even further.

Response safety – Earlier arrivals do not mean excessive speed or dangerous driving habits are warranted. On the contrary, it means that our driving and response skills should assure response safety is paramount. Apparatus accidents resulting from excessive speed or dangerous driving habits mean the arrival will be delayed and that resources now have two incidents to address. Operators need to understand their emergency vehicle and understand the dynamics of their operation during emergency conditions.
Earlier Extinguishment

Getting to the fire scene earlier is only half the battle. These efforts are all for naught unless you can actually begin fire extinguishment earlier as well. In "newer" buildings, our arrival is often dangerously close to the time when the building is going to flashover or beginning to experience structural failure, so it is critical that extinguishment begins as quickly as possible to reduce these circumstances.

Items that impact our ability to begin extinguishment earlier include:
 Employ the Most Appropriate Extinguishing Method

If all of the stars align and we arrive on scene with adequate resources and in time to make a positive outcome, we will still not be successful unless we make the proper tactical decisions necessary for the conditions present.

While this article is not intended to serve as a tactics and strategy training session, we do want to highlight a number of factors that fire officers need to consider when confronted with these buildings. These factors include:
 Summary

As the years go by and technology evolves, so do the hazards we as firefighters face. The modern day construction materials and techniques have brought and continue to bring new challenges to our profession and in order for us to be successful, we must recognize these facts, understand their impact, and adjust our operations if we are to continue to be successful and safe during future responses.

This article is intended to make you aware that we, as firefighters, need to be educating ourselves constantly and considering all aspects of our responses if we are to be successful. Without this mindset and approach, our ability to affect positive change will not only be reduced, but the risk to our firefighters will increase.

New York State Association of Fire Chiefs