BY P.J. NORWOOD AND JUSTIN McCARTHY
There has not been a day in the fire service when we have not heard the statement “Building construction is changing!” Even with the variations in materials and design, many of the changes have been forced into the standard five classifications of building construction we have always known. It has gotten to the point where we are starting to push the limits of those five classifications.
Another new construction concern for firefighters is emerging: Intermodal Steel Building Units (ISBUs), routinely called shipping containers. When shipping containers reach the United States, they are no longer used within the shipping industry and are routinely repurposed in a variety of ways. The public is accustomed to seeing these containers used for storage. The fire service is, and continues to be, very resourceful and inventive with our training. This mentality and ingenuity have adapted the ISBUs for flashover and other live fire training (photo 1).
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| (1) ISBUs are used for overseas shipping. Once they reach the United States, they are repurposed for a multitude of uses. (Photos by Frank Ricci.) |
For some of you, these structures are not new. Some fire departments have been conducting live fire training in ISBUs for years. However, the shipping containers we have become accustomed to for live fire training are now being used for residential structures. In New Haven, there is a private dwelling built completely out of ISBUs. The A or 1 side has been built up with a façade that blends into the neighborhood. Without proper preplanning or a proper size-up, including a 360˚ scene size-up, it would be difficult, if not impossible, to know that the building was built from ISBUs.
New Haven also has a three-story, multiple-occupancy apartment complex in which each of the six-unit apartment buildings is constructed out of 26 ISBUs. To add to the tactical dilemma, the structure is raised nine feet off the ground because it is in a flood-prone area. These multiple dwellings are provided with fire sprinklers.
These buildings obviously add concerns for firefighters. Some may believe we will be better equipped to handle fires in these structures because we conduct live fire training in ISBUs. It’s a big mistake to even consider that we are prepared for these fires, no matter how much training we have conducted in them. When we conduct live fire training in these units, the fuel load is limited to hay and pallets or oriented strand board (OSB) for flashover training. Along with the limited type of materials, the total amount of fuel is generally greatly controlled.
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| (2) ISBUs are designed to blend into the existing neighborhoods. |
The heat release rates (HRR) for a limited quantity of hay and pallets or some OSB are very different from the HRR for common household items. Residential homes are filled with many items that are basically petrochemicals, which are made by refining petroleum; these materials burn with greater speed and produce a much more volatile smoke than we have been trained for. Modern household fires create a ventilation-limited environment where pallets and hay create a fuel-limited fire. Fighting fuel-limited fires is very different from fighting ventilation-limited fires. This highlights a major problem: We are routinely training to fight fires that we are not seeing on the fireground.
The fireground today is different from the fireground of many years ago. Today’s fires, regardless of the type of structure, are becoming ventilation limited because of the HRR and the speed at which the products are burning. The public’s focus on energy savings has led to sealing up homes. Regardless of whether their homes are newly constructed or older, homeowners are concerned with maintaining a level of comfort in them, which leads to making the building more energy efficient. The lack of airflow contributes to ventilation-limited fires.
Building construction factors have altered many fire departments’ tactics because of the concern of a higher number of collapses. However, we are still fighting the majority of our fires the same way despite the changes in construction and fuel load. We must adapt our tactics to today’s fuel and construction changes. The operating time frame is the biggest tactical change we have seen with contemporary building construction features. Lightweight floors and trusses have decreased the time we have to complete some tasks. ISBUs will challenge your tactics, requiring that you change your fire attack plans and ventilation strategies. Following are some areas you should consider revising.
Figure 1. Fire Behavior |
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| The modern fire environment and modern household contents have changed the fire behavior model. Today, many fires are ventilation limited, which creates other tactical considerations for firefighters and officers. (Courtesy of the UL Firefighter Safety Research Institute.) |
TACTICAL CHALLENGES
Fire Attack
When discussing fire attack in an ISBU, keep in mind the following factors:
- Companies must make a proper stretch, have enough line, and have a proper water supply and flow and adequate gallons per minute (gpm). We cannot lose focus. Think of these buildings as flashover containers overloaded with fuel.
- We will face higher heat conditions and more volatile interior conditions because these buildings readily contain the heat compared with traditional structure fires.
- Construction features may impact your egress and restrict you from backing out. Take into account the areas of egress, both routine and emergency. Consider areas of refuge; they may or may not be available because of the construction features.
- As with all fires, use barriers to prevent flashover conditions as well as to protect firefighters from steam burns. One benefit to this type of construction is that the compartments are smaller than many of those in the new lightweight constructed, traditional homes built with open floor plans.
Because of these and other challenges, it is imperative that you get the first line in place with the proper gpm. Get water on the fire in the quickest way possible. That may be through an aggressive interior, transitional, or blitz attack or by attacking from the burned side.
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| (3) The façade on the A side highlights the necessity for a 360˚ size-up. The C side may reveal the true construction and the challenges firefighters will face. |
Search
Search tactics need to be modified regardless of the type of structure in which you are operating. When conducting search operations, put a greater focus on closing doors to create barriers and areas of refuge and to limit flow paths. Searching in the flow path is very dangerous. Crews must aggressively control all flow paths until water is flowing and cooling the environment.
The oriented search as taught and used for many years must be modified. We can no longer keep a firefighter or an officer in the hallway at the bedroom door while the other one or two members complete the search. We also cannot have a vent-as-you-go attitude. The officer or door-control firefighter should still stay at the door but inside the room with the door closed. Once members have entered the search room and the door is closed, the windows can be taken but only if the door is, and can be kept, closed.
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| (4) ISBUs are not used only for single-family homes. Their use in multiple-occupancy dwellings is also common. This six-unit apartment complex is under construction in New Haven, Connecticut. |
Ventilation
Look at everything you encounter on the fireground with a worst-case scenario vision. The ISBUs necessitate that you consider the ventilation component and the increased problems these buildings present. ISBUs are meant for goods and are designed to hold up to stacking, weather, and severe accidents during transport, which introduces the issue of cutting into the steel vs. completing horizontal vent operations.
In preplanning these structures, we noticed the thickness of the steel used for construction, but we also noticed the thickness of the structural “ribs” and how close together they are. Vertical ventilation will be an extremely time-consuming and challenging task for ventilation crews. Horizontal ventilation will take less time and demand fewer resources such as saws or torches. These buildings are designed to be efficient, meaning that windows may take some extra work. You may find impact-resistant or hurricane glass instead of normal glass in the windows. (Many builders are using hurricane glass and impact-resistant glass for security and efficiency in nonhurricane or tornado-prone areas.) However, horizontal ventilation tactics will still be easier than those for vertical ventilation.
During walk-throughs and inspections, note in all prefire plans any natural construction features that will assist in vertical ventilation.
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| (5) Inside the structure, once the wall or ceiling covering is removed, steel will be present. The steel offers challenges for many tactical objectives. |
Structural
Most ISBUs will be structurally sound based on their design to withstand many elements during transportation. During our inspection and walk-through in New Haven, structural stability surfaced as a concern.
The ISBU multiunit complex in New Haven, mentioned earlier, was designed by joining 26 steel containers to create one building. The structure was raised off the ground nine feet and placed on columns because of its location in a flood plain. The occupants will be using the space underneath for parking. The strength of the columns is a major concern because of the potential of their being struck by a car or facing force from a water surge. The containers are essentially “U” bolted to the columns.
During our walk-through of the interior, we found the building had a great deal of “give” as we were walking around. This is critical information to be relayed and noted on prefire plans. If an unfamiliar firefighter were operating in the interior, he may base the tactical decisions on this “give” and assume that it is unusual or a sign of a larger issue when in fact it is baseline. The flip side is that “give” is based on perception, so it may also cause firefighters to continue operating in an unsafe environment.
Once inside, we found each apartment traditionally framed and insulated with spray foam insulation (SPF), with drywall installed as the interior finish. You must consider the combination of drywall and SPF during overhaul and when predicting fire spread. This includes outside walls, which some may expect to be completely noncombustible.
When ISBUs are delivered to the construction site, they are windowless and often have only one large opening. This means every window, door, stairway, and so on has been cut into the building on site. This on-site modification may affect structural stability in ways we do not know.
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| (6-7) The interior of these ISBU homes use standard construction practices and materials. However, there are many voids between containers that are concealed behind walls and above ceilings. |
Access
Many of these containers are being used in green construction projects. The builders are trying to achieve Leadership in Energy and Environmental Design (LEED) ratings. Heat Island Mitigation is a big challenge in achieving LEED points. It is an innovative way to reduce air pollution and energy usage. LEED requires that at least 50 percent of the hardscape of a development be shaded or designed with permeable materials. Shading is usually accomplished by planting many trees. In some instances, this is a concern to the fire department because the trees are placed close to the structure, which could hamper apparatus and ladder placement.
Permeable materials such as pavers are used to achieve LEED points. Some of these permeable surfaces are made of new exotic materials other than the common asphalt and concrete on which most fire departments are used to staging their apparatus. The weight of your apparatus may be a concern.
Many LEED communities are also becoming “walkable communities.” Walkable communities have limited numbers of parking spaces. These spaces are often away from the homes, providing reduced vehicle access near the building. This could cause fire department access issues with staging, aerial ladder placement, and longer hose stretches.
The fire service is accustomed to altering and adapting responses and tactics to meet the needs of the community. The ISBU is another example that illustrates how important it is for all companies to do prefire planning. The building construction in your response districts will always be a dynamic changing environment that will necessitate altering your tactics. It’s your job to be ready for any emergency at any time in any building type.
Make sure you understand the buildings in your community. Understand the construction methods and materials used in these buildings and what surrounds them so you can effectively and efficiently mitigate problems as safely as possible. There are many resources that provide information on ISBUs and LEED. Take the time to learn about these responses before the calls come in.
References
New Haven Register: http://www.newhavenindependent.org/index.php/archives/entry/ahoy_the_containers_houses_are_coming/.
Green Maltese- http://greenmaltese.com/tag/shipping-container/.
Sources for additional information
http://containerhomes-info.com/.
http://www.kmbc.com/news/18414304/detail.html.
http://www.time.com/time/nation/article/0,8599,2047072,00.html.
http://www.bobvila.com/sections/home-building/articles/316-home-sweet-container/pages/1.
P.J. NORWOOD is a deputy chief training officer for the East Haven (CT) Fire Department and has served four years with the Connecticut Army National Guard. He has authored Dispatch, Handling the Mayday [Fire Engineering (2012)]; co-authored Tactical Perspectives of Ventilation and Mayday DVDs (2011, 2012); and was a key contributor to the Tactical Perspectives DVD series. He is a Fire Department Instructor Conference instructor, a Fire Engineering contributor, a Fire Engineering University faculty member, and co-creator of Fire Engineering’s weekly video blogs “The Job.” Norwood hosts a Fire Engineering Blog Talk Radio show. He serves on the UL Technical Panel for the Study of Residential Attic Fire Mitigation Tactics and Exterior Fire Spread Hazards on Fire Fighter Safety. He has lectured across the United States and overseas. He is certified to the instructor II, officer III, and paramedic levels.
JUSTIN McCARTHY is a firefighter in New Haven, Connecticut. He works as a fire instructor for the Wolcott Regional Fire School and is a Fire Department Instructors Conference instructor. He has a B.S. in fire science and has cowritten a Fire Engineering (2012) DVD series with Frank Ricci. He cohosts the P.J. Norwood Show on FE Blog Talk Radio.
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