KNOWING HOW BUILDINGS ARE PUT TOGETHER WILL HELP YOU TO UNDERSTAND HOW AND WHY THESE BUILDINGS CAN COME APART IN A FIRE.
BY JOSEPH F. RUSSO
A recent PBS series entitled “Building Big” chronicled the history of building high-rise structures around the world. Famous successes and dangerous blunders are part of the story. In addition to a history lesson, the viewer gets a sense of the evolutionary process that brought building construction from heavyweight, brick, mortar, and reinforced concrete to the lightweight metal deck, glass skin, and steel of modern high-rise structures. That trend has become more widespread, as can be seen at much smaller building projects.
 1 Photos by author unless otherwise noted. |
A survey of any fire company’s response area will likely reveal several new and renovated buildings in various stages of construction. An examination of these buildings is sure to be a thought-provoking experience. A revolution is now in full swing in the residential and commercial construction industries. Attempting to understand the change is an ongoing process, and a necessary one, for any fire service professional interested in staying alive inside a fire building. Knowing how buildings are put together will help you to understand how and why they come apart in a fire.
LIGHTWEIGHT CONSTRUCTION COMPONENTS
- Trusses. The trusses may be of wood or metal. Their quick failure in fires has been well documented around the country. Prefabricated off site, they are only as good as the manufacturer’s quality controls and the construction crew’s skill in installing them. Municipalities have rejected some trusses as defective because of improper gaps or missing glue. Weather and rough handling affect trusses, and trusses must be properly installed to be able to bear the designed loads. In recent years, buildings under construction have collapsed when a load was placed on an improperly supported area (Middleton Street, Brooklyn, New York, Nov. 23, 1999, for example). In another part of that borough, a strong gust of wind blew down a partially constructed frame building (see photo 1).
- Metal or “C” joist. This cold-rolled steel building product is favored partly because it does not add to the fire load. But remember, fire resistive does not mean failureproof. The main concern when encountering a metal joist is the lack of mass. Metal joists, like conventional steel I-beams, fail when a critical temperature is reached. If not properly enclosed and protected from fire, the failure can occur in minutes. Ribbons of twisted metal joists were observed at a Bronx taxpayer fire (see photo 2) and again at a multiple-alarm fire in a row of wood-frame dwellings in Brooklyn. It’s worth noting that both incidents did not involve new construction; they were renovations or additions to existing buildings.
- Combination of components. Typically, combinations of materials are used in lightweight construction. In one example, cold- rolled steel “C” joists are used to support engineered wood trusses and plywood I-beams (see photo 3). In another instance, peaked- roof trusses, held together with metal plate connectors (MPC truss), rest on 2 2 4 studded walls (see photo 4). There are many variations. Another common practice combines brick and block exterior walls with lightweight trusses or metal floor joists (see photo 5).
- Renovations. These include adding stories or pushing walls out to the property line, which creates structures in which old-style framing and new lightweight materials exist side by side.
 2 Photo by Richard Wolfson, Peter Vallas Associates. |
When you see a new building being erected or an older one under renovation, stop to examine which materials and construction methods are being used. Be curious, or be surprised by a building with a failure time for which you are not prepared. Experience has shown that lightweight building materials must be installed with great attention to detail. Shoddy construction techniques can be deadly. Weak connection points or poor or nonexistent fire stopping can have disastrous consequences in a fire (see photo 6).
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Firefighters of the 1960s and 1970s owe a debt of gratitude to the designers that crafted the building codes of the earlier years. The use of full-dimension lumber in the hands of skilled laborers and craftsmen, coupled with diligent inspections, resulted in well-constructed buildings with structural elements that contained much more mass and which, therefore, were more resistant to collapse. This made it possible for firefighters to engage in interior firefighting operations for longer periods of time.
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Now, many buildings are more than a hundred years old and are near the end of their life expectancy. Many are under massive renovation and present a similar set of problems as newly constructed structures. Among these are the vast amount of materials, held together with glue and gang nails (metal plate fasteners), that are above a firefighter’s head (see photo 7) and shoddy, rushed construction. In photo 8, you can see a gap between the slabs; this is the tip-off that the slab is not resting squarely on the support. This creates an eccentric load that is prone to failure.
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Current and future generations of firefighters need to be aware of which older structures have undergone renovation and have incorporated in them new lightweight materials and construction methods. These structures are more likely to collapse early in firefighting operations.
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- Premanufactured housing. This construction method produces entire buildings that have been welded and screwed together in a factory, much like mobile home construction, and dropped on foundations. They are present at various locations around the country (see photos 9, 10). When the exterior is completed, it becomes impossible to identify these metal-frame buildings. The only way to identify them and document their hazards for preplanning purposes is to inspect them at the construction site.
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Affordability is the excuse commonly given to gain approval for these new construction methods, but increased profit and outright greed are often the overriding motives.
WHAT THE FIRE SERVICE CAN DO
The fire service should do more than merely “sound the alarm.” We should also collect scientific data that will back up our demand for better-built structures. Fire departments around the country-better yet, around the world-must begin to build a database that incorporates every instance of the failure of a building product. Details about the failure should be recorded on the fire report, and the incident should be brought to the attention of the safety chief. A simple universal report form could be used to record the data (see Figure 1). These anecdotal records will become the foundation of the evidence that can be used to force change.
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Sharing information is also important. In the summer of 1998, during a fire in a high-rise multiple dwelling in Brooklyn, melted plastic wire molding in the public hallway melted and began dropping on firefighters (see photos 11,12). This molding, which holds coaxial cable wires, is commonly used in the telecommunications industry. This molding can present hazards for firefighters battling a fire in any jurisdiction. Sharing this type of information can save firefighters’ lives. Identifying patterns and trends can alert firefighters before a disaster occurs. There is presently no existing effective network by which fire departments can share such information.
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Fire department must have access to technical expertise. One way to do this is develop a relationship with universities that have strong architectural and engineering programs for the purposes of keeping up to date with new construction trends and materials and researching questionable conditions observed at a building site. This type of an alliance would also help the fire department to learn the appropriate terminology for construction features and other construction-related terms so that the fire service will be able to explain its position in a more professional manner.
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The building industry is a powerful lobby with unlimited funds. It may take the united action of the entire fire service to make our voice heard on this issue.
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We must be proactive so that we can avert tragedies. Fighting fires in buildings of lightweight construction calls for an adjustment of tactics. We need better methods for identifying the hazards involved and strategies for making more efficient use of hose streams so that personnel will be kept out of areas with unstable floors and roofs. The rules of the game have changed. A room-and-contents fire calls for an aggressive interior attack, but when fire involves the lightweight structural components or when the fire has hold of the structure’s combustible concealed spaces, our fireground tactics must be adjusted or changed to a safer method of firefighting.
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The building material and construction industries are aware of our concerns about lightweight building products. An article in Builder magazine (October 1999, p. 228) characterizes the objections of the firefighters in a quote from Ken Grundahl of the Wood Truss Council of America: “The problem is that you’ve got the fire service out there with emotion on their side, and they’ll play that to the hilt. Over here in the industry, we don’t have emotion. We have facts on our side. And they don’t have the same appeal.”
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In essence, he is claiming that the fire service’s argument is an emotional one that has more appeal than actual facts and that the industry’s information is based on scientific testing. But critics have declared the 80-year-old ASTME E119 testing standard used to test construction components invalid for today’s hotter fires fueled by plastics and synthetics.
Documenting, communicating, and networking are not enough. The intention is not to become adversaries of the building industry; it is to become advocates for our profession. We should write more articles, attend more conferences, read more journals, and network with other professionals. We have a unique opportunity during this period of rapid change in the building industry to have input that will affect the lives of firefighters for generations to come. The pen of history continues to write. How will it evaluate our actions or inactions during this period of the largest building boom in recent history? What will firefighters of future generations say about what took place on our watch?
JOSEPH F. RUSSO retired as a captain from the Fire Department of New York (FDNY) after a 32-year career. He is currently the director of fire safety engineering at Polytechnic University in Brooklyn, New York. He was an instructor in engine operations at the FDNY Fire Academy and is a writer and lecturer on firefighting topics in the United States and Canada.
