Entering Through the Door, Falling Through the Floor: Catastrophic Structural Collapse

by Azarang (Ozzie) Mirkhah and Sean DeCrane

Concern about the poor performance of the engineered lightweight wood construction under the fire conditions is nothing new. We have known about it for more than a couple of decades. Obviously, the first name that comes to mind when talking about this subject is the legendary Francis Brannigan and his famous book, Building Construction for the Fire Service. There are many great reports, but just a handful of them are mentioned here. Back in 1992, United States Fire Administration (USFA) did a report, titled "Wood Truss Roof Collapse Claims Two Firefighters (December 26, 1992)"; National Institute for Occupational Safety and Health (NIOSH) did a report on April 2005 titled "Preventing Injuries and Deaths of Firefighters due to Truss System Failures"; National Institute of Standards and Technology (NIST) did a report on January 2007 titled "A Study of Metal Truss Plate Connectors When Exposed to Fire".

Through his writings and all his presentations, Brannigan tried for years to teach us about the importance of having a good working knowledge of building construction and repeatedly advised us to "know your enemy." Fire service members have not fully grasped this concept yet, at least not as well as we should. This year, it seems that there wasn't a month that went by without reports of firefighter fatalities and injuries resulting from catastrophic structural failures under the fire conditions.

On April 4, 2008, a veteran Colerain Township, Ohio Fire Capitan Robin Broxterman and Firefighter Brian Schira were killed in the line of duty when they fell through the first floor of a working house fire. The fire was in the basement of a two story, four-bedroom house built in 1991. Reports indicate that the alarm came in shortly after 0600 hours. Captain Broxterman and firefighters Kenny Vadnais and Brian Schira went into the burning building. Three went in, but only one came out. Firefighter Kenny Vadnais believes he is alive today because Robin and Brian helped him escape the fire's death grip. No other injuries were reported. The two occupants of the house made it out before the firefighters arrived on scene (see http://firefighterclosecalls.com/fullstory.php?63098)

When a firefighter dies in the line of duty, the National Institute for Occupational Safety and Health (NIOSH) will respond and conduct an investigation into the event. NIOSH's intent is not to find fault or lay blame. Their intent is to learn lessons from the mistakes or events, and to release a report with the results of their investigation. The report is a public document and fire departments are encouraged to review the report and learn from the events that led to the firefighter's death.

To get a perspective of the real world performance and its effect on firefighter safety, let's look at two relatively recent incidents investigated by NIOSH. Below are the summaries of these two reports and the recommendations published as a result.

Incident - 1: "Volunteer Fire Fighter Dies After Falling Through Floor Supported by Engineered Wooden-I Beams at Residential Structure Fire - Tennessee"
http://www.cdc.gov/niosh/fire/reports/face200707.html

On January 26, 2007, a 24-year-old volunteer firefighter died at a residential structure fire after falling through the floor which was supported by the engineered wooden I-beams. The victim's crew had advanced a handline approximately 20 feet into the structure with zero visibility. They requested ventilation and a thermal imaging camera (TIC), in an attempt to locate and extinguish the fire. The victim exited the structure to retrieve the TIC. When he returned, the floor was spongy as conditions worsened which forced the crew to exit. The victim requested the nozzle and proceeded back into the structure within an arm's distance of one of his crew members, who provided back up while he stood in the doorway. Without warning, the floor collapsed, sending the victim into the basement. Crews attempted to rescue the victim from the fully involved basement, but a subsequent collapse of the main floor halted any rescue attempts. The victim was recovered later that morning. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should:


  • Use a TIC during the initial size-up and search phases of a fire

  • Ensure firefighters are trained to recognize the danger of operating above a fire and identify buildings constructed with trusses or engineered wood I-beams

  • Consider modifying the current codes to require that lightweight trusses are protected with a fire barrier on both the top and bottom.

Incident - 2: "Career Engineer Dies and Fire Fighter Injured After Falling Through Floor While Conducting a Primary Search at a Residential Structure Fire - Wisconsin"
http://www.cdc.gov/niosh/fire/reports/face200626.html

On August 13, 2006, a 55-year-old career engineer died and another irefighter was injured after falling through the floor at a residential structure fire. The victim and the injured firefighter had arrived in their ambulance and assisted the first-due engine to attach a five-inch supply line at approximately 1227 hours. The engine company was conducting a fast attack on a suspected basement fire while a ladder company conducted horizontal ventilation. The ambulance crew had advanced to the front of the structure when the incident commander requested them to conduct a primary search. The victim and the injured firefighter proceeded to conduct a left hand search at approximately 1234 hours. They took a couple steps to the left just inside the front door to conduct a quick sweep. Visibility was near zero with minimal heat conditions. Because of the smoke conditions, they kneeled, sounded the ceramic tile floor, and took one crawling step while on their knees. They heard a large crack just before the floor gave way, sending them into the basement. The basement area exploded in a fireball when the floor collapsed. The victim fell into the room of origin while the injured fell on the other side of a basement door into a hallway. The injured firefighter was able to eventually crawl out of a basement window. The victim was recovered the next day. The NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should:


  • Conduct preincident planning and inspections of buildings within their jurisdictions to facilitate development of safe fire ground strategies and tactics

  • Use a TIC during initial size-up and search phases of a fire

  • Ensure firefighters are trained to recognize the danger of operating above a fire and identify buildings constructed with trusses

  • Consider modifying the current building codes to require that lightweight trusses be protected with a fire barrier on both the top and bottom.

Three lessons should be taken from these two reports. One, these types of dangers impact all firefighters, both career and volunteer. Fire does not know the difference or care; it is an equal opportunity killer. Two, both reports emphasized the importance of firefighters knowing the dangers of operating over a fire and identifying buildings with trusses. Third, both reports recommend that the fire departments should modify the current building codes to require that lightweight trusses be protected with a fire barrier.

During the recent International Code Council's (ICC) Final Action Hearings in Minneapolis for the 2009 edition of the building construction codes, by actively participating in modifying the deficiencies in the current building codes, the fire service attempted to address lesson three. There was a code proposal that would have required lightweight construction in residential properties to be protected with a 30-minute barrier.

The attendance at the final action hearings set a record in the number of fire service attendees. The majority of those attendees were there to support the proposed requirement of residential fire sprinklers in one and two-family homes. As you know, that proposal passed with a strong 73 percent majority, receiving 1,282 votes.

The proponents of the code change to require the protection of lightweight construction hoped for success because of the large fire service attendance. Another encouraging sign was the fact that the code change to require the barrier was scheduled to be heard immediately following the residential fire sprinkler proposal. Surely the fire service would remain to vote on such a critical safety issue.

Unfortunately, during the debate on the code proposal for the protection of lightweight construction. we could see large numbers of firefighters leaving the room. In the subsequent vote, the proposal requiring the fire barrier received a majority of the votes, but fell fifty votes shy of the required 2/3 majority required to be accepted into the codes. The proposal received over 700 votes. That means approximately 500 firefighters left the room after the sprinkler vote. We were not as coordinated and organized as we should have been, and the fire service attendees were not well informed about the code hearing process and procedures. As a result, they believed their work was successfully done and there were no more fire-related proposals to be voted on, so it was time to leave; just as they are used to returning to the fire station right after responding to an incident and putting out the fire. But if only 60 fire fighters would have stayed for the vote, we could have passed the requirement to protect lightweight construction--exactly what NIOSH had recommended numerous times.

We will not give up our efforts to protect our firefighters. The fire service will be back in force, and we will be much better organized and more prepared. We are in it for the long run. In March 2009, another code proposal will be submitted in the ICC code process attempting to address this issue once again at the Code Action Hearings in October 2009 in Baltimore.

But remember that all these efforts would only enhance safety in the new houses being built in the future, and will not have any impact at all on the exiting homes. Now let's take a look to see what we in the fire service can and must do to reduce our firefighter fatalities in the exiting homes. That is especially important when you consider that there is an inventory of more than one hundred million existing homes around our country, and that a majority of those built in the last twenty years were constructed with those lightweight wood trusses.

The question fire service leaders must ask is: What can we do to reduce our firefighter fatalities resulting from such structural failures?

As a rule, in the fire service "we risk a lot to save a lot, and risk a little to save a little." Looking at it from the firefighters' safety perspective, then: We have the option of staying out protecting exposures with defensive operations. Although contrary to our current aggressive "interior attack" mode of operations, is a viable option that fire service members should seriously consider. Simply stated, when it comes to the lightweight wood truss construction, it might be best to stay out from the get go and protect our own firefighters.

Considering our professional obligation and deep commitment to saving lives, this might be a lot easier said than done. We would still be charging in full force if we believe that someone might be trapped inside and a life could be saved. But we should also remember our commitment is to save lives, including our own.

Simply stated, we should not be risking firefighters lives for houses built without much fire resistive rating and no active fire protection systems if there are no civilian lives to be saved in the first place. Buildings are disposable. Lives aren't, and that goes the same for our firefighters' lives.

To get a clear picture of why we should stay out and keep our firefighters safe when there are no lives to be saved, take a look at the latest Underwriters Laboratories (UL) report released on October 1, 2008. Last year, UL received a fire grant from the Department of Homeland Security (DHS) to do a research study on the performance of the lightweight construction under the fire conditions. UL conducted a series of tests, and just this month posted the results of their study titled "Structural Stability of Engineered Lumber in Fire Conditions" on their UL University Web site
http://www.ul.com/fire/structural.html
.

This is a great online course, free of charge and available to all. This course is essential for all firefighters and an absolute must for all incident commanders and fire safety officers across the land. It is only 52 minutes long but it is absolutely worth it. Please take the time to educate yourself and the staff under your command. The lives that they save could be their own.

Just to give a brief overview, UL did six tests and videotaped them all. They had two firefighter mannequins in full gear with TICs on these test floors and roof assemblies. Watch the videos and see if you can predict when the mannequins will fall through.

It is interesting to see that the difference in the temperature reading of the TIC at the top assembly compared to the inferno below. In one test, after five minutes, the TIC temperature showed a comfortable 73 degrees on the floor level above the fire; meanwhile, the temperature below was 1,378 degrees. This was not because TIC was not working or reading inaccurate temperatures; but because the flooring and carpets do not transfer that temperature, so the TIC doesn't see it.

Briefly stated, based on this report, the lightweight construction, the increased fuel load, and the synthetic petroleum-based materials in modern structures all contribute to much greater fire growth. Needless to say, faster fire growth significantly increases the probability of sudden catastrophic structural failure in these buildings. Time is working against us when fighting fires, and delayed response times could have direct adverse impact on the outcome of the call. Time is a luxury we don't have when responding to these lightweight construction fires; catastrophic structural collapse and firefighter fatalities could be the end result.

Take a look at the "Time versus Products of Combustion" illustration posted on the United States Fire Administration (USFA) Web site. You can clearly see that the increase in time directly correlates to the magnitude of fire and significantly increases the hazards facing our firefighters. This USFA's illustration underlines the impact of response time and the importance of residential sprinklers in early suppression of fires: http://www.usfa.dhs.gov/downloads/pdf/coffee-break/time-vs-products-of-combustion.pdf

It is positive to see that, slowly but surely; the fire service is finally realizing the importance of their active participation in the code development process. This participation will not only protect our communities and provide for the safety of our citizens, but also the firefighters putting their lives on the line day in and day out. Organizing the fire service to actively participate in the code development process is our task, as identified by Strategy 5 of the Vision 20/20 National Strategies for Loss Prevention, which is focused on this very important issue.

We were successful in getting the residential fire sprinklers into the codes, which was a big gain, but we failed to get the 30-minutes lightweight construction protection. We will keep on fighting for it and will undoubtedly succeed in future. We owe it to Robin Broxterman and Brian Schira and all of our other brothers and sisters who gave their lives fighting fires.

Buyers Guide Featured Companies



More Buyer's Guide >

Fire Dynamics

Survival Zone

Extrication Zone

Tech Zone