By Kevin A. Gallagher
It didn’t take long for this web column to be noticed by officials of the Modular Building Systems Association. The October 2013 feature ("Modular Construction: Hidden Hazards Within") was quickly responded to by the Association’s Executive Director, Tom Hardiman, by a letter to the editor of Fire Engineering. The good folks at Fire Engineering allowed me to write a response, and both documents were published in the magazine’s December 2013 issue, found HERE.
The issue is quite simple: On one side—me—is the belief that certain construction techniques used in prefabricated (modular) construction behave poorly under fire conditions. On the other side—Hardiman—is the belief that there are no concerns, and that this is nothing but an attack on an industry by a small-town guy looking for attention.
I do not intend to use bandwidth to engage in a protracted, long distance slugfest with Hardiman. His top priority appears to be to protect the modular brand, while my top priority is to protect your back. However, certain charges leveled in the letter to the editor and a November letter to the Massachusetts Board of Building Regulations and Standards, of which I am a member representing Massachusetts fire chiefs, got my Irish up. So, before we get back to a discussion of firefighter safety considerations in light of construction techniques unique to the modular industry, please allow me a few minutes to clarify, reiterate, and possibly pontificate.
The Hardiman letter to the editor challenges me, to paraphrase Hardiman, to put up or shut up. “What evidence is there to show this problem really exists anywhere outside of Gallagher’s mind?” Hardiman asks. Now, I am intimately aware of what is "in Gallagher’s mind.” Locked in there is some knowledge, based on 28 years of fire service training and experience, that something was different the morning of January 13, 2008, when I stood in the street and saw a two-story colonial fully involved, a fire that had been reported just moments before as confined to the porch (photos 1,2). That part of my mind helped me decide to contact the Massachusetts State Fire Marshal’s office and request an investigator from the state police even before fire suppression activities were completed. The speed of this fire challenged a lot of talented, experienced minds that morning. Bringing in a highly professional investigator from a highly respected service seemed prudent.
(1) January 2008 fire in Acushnet, Massachusetts, of two-story modular. (Photos by author.)
(2) Remains of the structure in Acushnet.
What evidence is there? Let’s start with the report issued by the state trooper who investigated this fire. Refer to page 2, item #6, which reads, in part, “This building was a prefabricated dwelling, consisting of four boxes that were assembled on site. When the upper boxes are placed on top of the lower boxes, a large void space is created between the first and second floors. This void space coincides with the roof line of the front porch. As the fire began to roll under the porch roof, it extended into the void through several holes. The fire was probably burning in the void when discovered by (an occupant).”
So, the trooper, in a report written five days after the fire, following his investigatory processes, states that the fire extended into the void space and was probably burning in the void for a period of time prior to discovery.
The report continues, “During the construction of a prefabricated home, glue is used in addition to nails to add additional strength for transport to the construction site. The glue is highly flammable and may have aided in the rapid extension of the fire.”
So, the trooper is concerned by the possible role of flammable glue in this fire that destroyed a family’s home and possessions, and from which they narrowly escaped.
The 2008 report from the Massachusetts State Police is found HERE.
From my personal observations, the concerns raised by our department members who witnessed this fire and the official report from the state fire marshal caused us to ask questions that the modular industry doesn’t like. What Hardiman doesn’t understand is that there isn’t a fire officer in this country that, when confronted with the same gut feeling (observations tempered by experience and training) and investigative reporting, wouldn’t ask as many questions as necessary to make sure the members under their command are as safe as possible.
(3) Investigators at scene of the January 2008 in Acushnet.
What evidence is there? It is from scientific data from Worcester Polytechnic Institute (WPI), one of the premier fire science colleges in the nation. A cone calorimeter test was conducted on samples of glue from a new modular home in my community. To summarize the findings, the glue ignited quickly, burned hot, and lost nearly all its mass (click HERE to view the findings). Should we be concerned? Knowing that the industry uses this type of glue as the sole means of attaching gypsum to structural members, then yes, we were concerned enough to keep asking questions.
What further evidence is there? From a second round of tests conducted at WPI which indicates the polyurethane foam structural adhesive sample from the Acushnet home referenced above begins to change its physical state from a solid to a gas at 482°F (250°C). As the researcher informed us, “As the temperature of the foam continues to rise the foam continues to decompose (mass is lost).” He further states that he would expect the mechanical strength of the foam to also decrease.
So, researchers have determined that at 482°F we can expect the glue—the only thing holding up the ceiling—to begin to lose its “mechanical strength,” also known as the ability to hold the ceiling in place. Remember, the ceiling opens into a large void space already cited by a fire investigator as a pathway for fire.
What evidence is there? It is from a similar cone calorimeter test conducted by Hughes Associates of Maryland, a respected and well established firm hired by the Modular Association to conduct two tests on ceiling assemblies. The tests were conducted at the time Massachusetts code developers were about to vote on a measure to close a code loophole, which allows glue to be used in place of mechanical fasteners (photo 4). The board received the attached project summary, which includes adhesive calorimeter results very similar to the data collected by WPI researchers (ignites fast, burns hot, high mass loss) (Click HERE to view summary.)
(4) Inside a typical void space between levels of habitation. Note the glue holding sheetrock to wood structural member.
It is interesting that included in the January 6, 2011, letter from Hughes Associates to the Modular Association is a description of the strength testing characteristics of the three different foam adhesives that they tested. The authors of the letter state the three products met the qualifications set forth in Progressive Engineering, Inc. (PEI) Standard 93-7, Performance Requirements for Fastening Gypsum Board to Wood Framing Using a Two Part Urethane Adhesive. After reviewing this standard, by which the industry justifies using glue in place of screws, the Hughes researchers state the following:
“This standard evaluates the tensile and shear strength performance of the foam adhesive test samples at nominally ambient temperatures. These tests are not performed at elevated temperatures representative of fire exposure conditions, therefore, the actual tensile and shear performance of these foam adhesives, at elevated temperatures, is unknown.”
So, Hughes Associates warns the Modular Building Systems Association that this stuff was never tested under fire conditions and that its performance under fire conditions is not known. This warning comes not from the fire service but from their own consultant.
What evidence is there? As the vote on requiring mechanical fasteners approached, the association sent the attached letter stating that Hughes was unable to complete the test in time and that the results would be forwarded to the board. Three years later, we are still waiting to receive the results. (Click HERE to view the letter.)
What evidence is there? In his letter to the editor, Hardiman states that the Hughes testing process yielded inconclusive results and that the tests were stopped prior to the finalization of any written report. In a recent letter to the Massachusetts building code board, copied to the Governor and other state officials, Hardiman contends that this research costs “well over $100,000.” I imagine that if the test results confirmed that this issue “only exists in Gallagher’s mind,” then after investing more than $100,000, it would have been broadcast far and wide. Instead, the data remains locked up in the files of Hughes Associates, with the findings known only to a select few.
There is no way the modular folks are going to provide me the test results to share in this space. Perhaps the “inconclusive data” should be sent to the researchers at WPI; let them see what you see. They don’t have a dog in this hunt. As the fire service is coming to learn, follow the science.
As members of the fire service, judge for yourselves! Look at the data available, conduct your own research, and ask questions. Remember the concerns of those that came before us regarding balloon frame construction and ask yourself if a horizontal cockloft that runs the length of the residence is a concern during a fire. Consider glue that no one has tested under fire conditions (except Hughes Associates) being the only thing holding up the ceiling; a ceiling that, if penetrated, opens into the void space. What does your gut (observations tempered by experience and training) tell you?
I want to believe that the Modular Association would want to test those construction techniques, analyze the data, and follow the science.
Kevin A. Gallagher has served with the Acushnet (MA) Fire & EMS Department since 1986, where he was appointed as chief in 2003. Gallagher has an associate degree in fire science and a bachelor’s degree in political science. He is an adjunct instructor in the Fire Science Program at Bristol Community College. Gallagher serves as the Fire Chiefs Association of Massachusetts representative to the Board of Building Regulations and Standards, the Massachusetts board responsible for overseeing the state’s building code. He has contributed articles to Fire Engineering and has taught several classes at FDIC on the issue of modular construction.