(August 2011)

Update on the dangers of modular construction

This is an update to my article, “The Dangers of Modular Construction,” published in May 2009. In January 2011, Massachusetts took the lead in addressing an issue of importance to the safety of firefighters and the occupants of buildings of modular (prefabricated) construction. At issue are the polyurethane foam structural adhesives used by the modular industry to attach gypsum board to wood framing in ceiling assemblies. As of February 1, 2011, the following section of the Massachusetts State Building Code went into effect:

5702.3.5.1 Ceiling attachment. Effective January 13, 2011, only designs or methods that use mechanical fasteners in accordance with 780 CMR Table 5702.3.5 shall be used for attaching gypsum board to ceilings in buildings governed by this code, including manufactured buildings. Alternative designs, such as using adhesive only, are not permitted.

The importance of this change, approved unanimously by the Massachusetts Board of Building Regulations and Standards (BBRS), is that it followed a period in which the modular construction industry offered to conduct testing to prove the fire service wrong but, in the end, failed to do so.

In January 2008, a fire destroyed a two-story, single-family colonial-style home in my community of Acushnet, Massachusetts. The speed with which the home was destroyed stunned us who fought and investigated this fire. The cause was the careless disposal of smoking materials in a dried-out flower window box situated on the farmer’s porch. The homeowners awoke to the increased sensation of heat, discovered the fire on the porch roof, and safely exited the structure. Within four minutes of their exit, the building was declared 75 percent involved by the first-arriving public safety official. Fire was seen from miles away inside a thick black column of smoke. The home and all of its contents were destroyed.

In the weeks and months that followed, we focused our investigation on certain construction techniques that are common to the modular industry but are yet relatively unknown to the fire service. First was the creation of large void spaces between levels of habitation. We should have seen this coming. When a modular home is constructed in a factory, the structure is built in a series of boxes (or modules) that are then shipped to the homeowners’ location and assembled on site. Each box comes with the floor and ceiling assemblies complete. When the boxes are stacked one on top of the other, the ceiling of the lower level can be as much as 20 inches from the floor decking of the upper level. This void runs the length and width of the stacked boxes, often 48 feet × 14 feet in dimension. The result is a mini cockloft that crosses from one side of the building to the other. Because the area of this void space doesn’t exceed 1,000 square feet, the International Residential Code (IRC) does not require draftstopping. Efforts to reduce the trigger for draftstopping was defeated during the 2009 International Code Council’s code development process.

The second area of concern is the widespread use of polyurethane foam structural adhesives as the sole means of affixing the gypsum ceiling to the wood framing. The IRC establishes a schedule for the use of mechanical fasteners in ceiling assemblies. This schedule allows for the use of fasteners with and without the use of adhesive. Simply put, based on the thickness of the gypsum and the size of the wood framing, certain size screws are to be placed at a prescribed distance apart from one another. When adhesives are used, the spacing of the mechanical fasteners is elongated. Nowhere in the code does it state that ceilings can be attached by glue only.

Then why, we asked, do certain evaluation reports list the stated use of the polyurethane foam structural adhesives as an alternative to mechanical fasteners? The industry is on record stating that the use of these adhesives as the sole means of attaching gypsum ceilings is widespread. It cites the bonding capabilities and the absence of “nail pops” or mechanical fasteners popping through the ceiling during transport. Through research and inquiries with code developers, we determined that the authority for the use of glue only in modular ceiling assemblies stems from the “alternative materials, design, and methods of construction” clause found in the IRC and other building codes (Massachusetts, for example). Through this administrative mechanism, a construction method can be used in place of a code-specific method if the new method meets the same performance criteria as the method or item it is designed to replace. In this instance, through the product evaluation process, it was determined that the glue meets the same performance capabilities of mechanical fasteners. Does it?

With the assistance of researchers at Worcester Polytechnic Institute (WPI) in Worcester, Massachusetts, we determined that samples of the glue obtained from a new modular home in my community ignited fast (time to ignition: seven seconds), generated significant heat (peak heat release: 241 kW/m²), generated thick smoke (peak smoke obstruction: 1.199 m²/g), and lost most of its mass (peak mass loss rate: 0.120 g/s) when subjected to heat energy (35 kW/m²).

When commenting on these test results, the industry stated that the products used in its construction processes met the specifications found in ASTM C557 (Standard Specification for Adhesives for Fastening Gypsum Wallboard to Wood Framing) and, therefore, met the same performance standards as mechanical fasteners. It also questioned the results of the WPI testing. A review of the ASTM standard often cited by the industry as the means by which authorization should be granted as an alternative to screws is compelling.

The scope of C557 is clear: It “covers minimum performance standards for adhesives intended to bond the back surface paper of gypsum wallboard to wood-framing members.” Keep in mind that mechanical fasteners (screws) use all three components of the gypsum (back paper, core, and face paper), which are anchored into the wood by the fastener). The standard also “covers test requirements and test methods for the application of all thicknesses of gypsum wallboard.”

The standard then details several tests to which the adhesive is subjected, ranging from four specific shear strength tests to storage and staining. The standard does require three tests that test the product at 0°F, 100°F, and 158°F. Understand that to achieve the performance requirements contained in this standard, the adhesive/gypsum specimen is subjected to no more then 158°F for 500 hours to test accelerated adhesive aging.

Why is this a concern? A second round of testing was completed by WPI researchers. Using thermogravimetric analysis, which is used to determine changes in weight in relation to changes in temperature, it was determined that at 482°F, the chemical and physical structure of the adhesive begins to degrade—in other words, the decomposition (the change from a solid to a gas) of the only substance used to hold the back paper of the gypsum to the wood framing begins.

As firefighters and fire officers, we know that the temperatures at the ceiling level in a room-and-contents fire can quickly climb to 1,000°F. If that condition were to arise, it would only take 48 percent of the generated heat to transfer through the gypsum before decomposition begins. Once the glue loses its adhesive bond and pulls away from the structural member, a gap is created that can allow fire to travel to the void space or attic area above.

Armed with this information, we petitioned the Massachusetts building code board to change the state code to—in essence—close the loophole created by the alternative design clause. The industry presented its information and requested a period of time to conduct testing of the product under fire conditions. Specifically, it offered to conduct a “flame under” test, where a section of gypsum attached to wood framing would be subjected to heat conditions with the goal of measuring failure rate. In addition, a void space would be constructed, mimicking actual modular construction techniques, with fire introduced to measure failure based on direct flame impingement. The BBRS, to its credit, approved the code section but provided a six-month period for the testing results to be delivered. At the industry’s request, this deadline was pushed back an additional three months. Shortly before the January 11, 2011, deadline, the board was informed that the test results would not be forthcoming. Based on the industry’s failure, after a period of nine months to provide testing data disproving our theories and concerns, the code change was approved.

The fire in 2008 started as a local incident. From our investigation and research, it has proven to be so much more. Simply put, we are stunned that such a highly flammable product has been allowed to replace screws in the ceilings of countless thousands of homes across the country. Our goal has always been to learn from this incident and use the knowledge we have obtained as a driving force for code change and firefighter education and awareness on the hazards hidden behind the gypsum in modular buildings. Massachusetts has taken the lead. Other states hopefully will follow.

Note: Massachusetts Fire Marshal Stephen D. Coan and I have produced the presentation “Residential Construction Fires—Lessons Learned,” which is available online for downloading through the National Fallen Firefighters Foundation at www.everyonegoeshome.com. Click on the “Learning Media Resources” button at the left of the home page.

Kevin A. Gallagher
Chief
Acushnet (MA) Fire and EMS Department

Kudos to Fire Engineering’s Blog Talk Radio

Iam a 20-year veteran of the fire service. I have recently started listening to the archives of Fire Engineering’s Blog Talk Radio podcasts. I want to thank the editors of Fire Engineering for adding this medium to your already excellent magazine family. I have yet to make it to the Fire Department Instructors Conference (FDIC). I’m not sure why I never had the desire to attend before now, but now that I am one of the training officers for my department I am anxiously awaiting the opening of the 2012 FDIC registration. Thank you again for keeping Fire Engineering on my fire service resource list. I hope to see you all at FDIC in 2012.

Nate Howe
Lieutenant
Kennebunk (ME) Fire Rescue

Show the resiliency for which firefighters are known

It is time for firefighters around the United States to band together and fight for the profession we all love. More and more, the fire service is challenged and plagued with budget cuts that cause a dramatic shift in how we operate and even in how we view our existence. Many departments are laying off, furloughing, and closing firehouses. Those of us left to hold down the fort feel deserted and cheated. The public and government leaders are not standing up for us the way we thought they would—or should. We have always been looked up to as the service that will do its all under any circumstances. The world views us as sacrificial lambs in the case of an emergency. The World Trade Center attacks gave a view into our profession and the devotion with which the fire service perseveres in the face of the impossible. Now, when we need the public and government leaders to fight for us, they take off their gloves and call it quits. It is time we stop blaming everyone for our misfortune and fight through it the way firefighters have done for hundreds of years before us.

In firehouse after firehouse, you see a lot of the same issues and mentalities. Firefighters are doing the bare minimum because our departments have been stripped down to bare minimum staffing, equipment, apparatus, and money. Let’s rise up and show the public the resilience and determination of our profession. Push forward, and stop complaining about what we lost. Officers need to build their houses instead of continuing to weaken them by falling into the poor-us mentality. We always say that we would do the job for free; the minute they make it uncomfortable for us, we start complaining and crying. We are firefighters and do not bow down or lose. Stop fighting. Don’t slow down, give up, or GIVE IN! Let’s train harder, speak louder, and get to know our neighbors. We have been in a state of complacency for a long time, and I’m afraid we are suffering the repercussions of our complacency.

We run calls and complain about the misuse of 911 and the ridiculous calls to which we are dispatched. How about fighting for what we can change and dealing with what we have no control over? If you can make a change, do it. If you can’t, then deal with it. We have a great profession and at times not the best job, but our profession is still very strong. Don’t get lost in the words, but take in the message. My proposal is that we fight for the profession we love. Sometimes that means fighting under the worst of environments, putting down pride, and making things happen for the sake of legitimizing what we do, “Save Lives.” When you come in in the morning, do everything in your power to make sure you are at 100 percent, even when you are bombarded with negativity. Let’s make sure that the public knows we can always be counted on no matter how tough things get or how bad we are treated or disregarded. The resiliency is what makes us firefighters—the ability to persevere through anything.

Pabel Troche
Firefighter/Paramedic
Smyrna (GA) Fire Rescue

Editorial inspires firefighters to be their best

“Four Brave Men” (Editor’s Opinion, May 2011) is probably the best piece of fire service literature I’ve read! Bobby Halton was able to tie together personal accountability, pride and ownership, and back to basics without ever dropping an industry catch phrase. He successfully crafted his editorial to leave the reader inspired to be the best member of his company while having faith that his fellow firefighters will be beside, behind, above, and below him as they attack their own lion!

I will be distributing this editorial in recruit schools for years to come and will be forwarding it on to the company officer certification program coordinator.

Chris Johnson
Firefighter
Concord (NH) Ladder Co. 1
Staff Instructor
New Hampshire Fire Academy

Combination nozzles offer options

This refers to Jerry Knapp’s comments on fog nozzle training (Letters to the Editor, March 2011). Using straight stream nozzles for primary attack is like driving a car with only one gear, forward. The combination nozzle does deliver quite an effective straight stream, which can be slightly or greatly altered as fire combat needs occur. As when driving, you need several gears: low gears for starting out and acceleration; higher gears for cruising and when needed; and the lower gears for specific uses—lower speeds, rapid acceleration for passing, climbing steep grades, and so on. The combination nozzle provides this spectrum of possibilities, narrow to wide streams and all in between. The nozzleman can avoid becoming a lobster if he has been properly trained to use the nozzle as it should be used.

The comments Knapp made on fog nozzle use in flashover training (“We wholeheartedly agree with the author’s assumption that the idea that a fog stream will protect you during a flashover likely came from propane training”) are not totally accurate. The most realistic and viable flashover training has been, still is, and probably will be for a long time using solid fuels in the container. If the Rockland County Fire Training Center is using propane simulators for flashover training, it is doing just that—simulating. The gas-fueled simulators do not recreate conditions similar to those of a “typical” confined space fire such as a home living room or bedroom. These real-world occupancies normally contain wood, textiles, plastics, and so on. These fuels do liberate considerable quantities of combustible fire gases, which are never quantified by the firefighters entering the space and applying the wet stuff on the hot stuff in correct and adequate quantity, time, and place. Besides, as you all too well know, if the conditions in the gas-fueled simulator get untenable, the training supervisor can simply turn the valve and cut off the fuel flow. In the solid-fueled simulator, you have to put the fire out.

Yes, we are indeed in the 21st century, 55 or so years onward from those early real trial-and-error investigations. But as I said above, training in the proper and adequate use of the combination nozzle gives the nozzle operator many more options.

George H. Potter
Fire Protection Specialist
Madrid, Spain