Article and photos by Gregory Havel
We are all familiar with the “engineered steel building” (photo 1). Most of us shop and get our vehicles serviced in them. Our fire station or job away from the fire service may be housed in one of them. The traditional building of this type (photo 2) has a frame of steel I-beam arches, with a widened “haunch” at the joint of the roof with the walls to redirect the forces downward instead of outward. The foundations to which the column bases are bolted may be tied together by steel rods under the floor if there is a basement or tied into the concrete floor with rebar for added stability. Lightweight steel channels are used as purlins to support the roof and to attach the wall panels.
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The insulation used in a traditional engineered steel building is plastic-faced fiberglass batts in long rolls, often eight or 10 feet wide (photo 3). The insulation is attached to the wall framing with the plastic face inside. The prefinished ribbed steel wall panels are overlapped for a weather-tight joint and screwed to the wall framing from the outside of the building and through the insulation. The lower part of the inside of the walls is often covered in matching ribbed steel panels or with plywood or oriented strand board (OSB) to protect the insulation from damage and to give a solid surface for shelving and displays.
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The roof is insulated with the same material as the walls. The roof is usually finished with prefinished standing-seam or overlapping ribbed-steel roof panels, screwed into the roof framing through the insulation. A bundle of standing-seam panels is shown on the roof framing in photo 3, before the insulation and roof panels are installed.
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A new variety of wall panel is being used in some new engineered steel buildings (photo 4). These panels are made of an inner and outer prefinished steel face, with two or three inches of foamed-in-place polystyrene installed at the factory. These panels have interlocking edges, with a sealant in the outer channel to ensure a weather-tight joint. These panels are attached to the purlins with self-drilling screws into the inside face of the panels. The exterior walls are complete when installed and require no additional protection for the insulation. The roof will be insulated and installed as in the traditional-type building.
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A tip: If the exterior of the building shows rows of screws or bolts holding the wall panels, it is probably the traditional style with a single layer of steel. If there are no visible rows of screws or bolts, it is probably a double-faced insulated steel panel, or it could be a single-layer panel attached with concealed fasteners.
Firefighters must be aware of potential problems with a fire in one of these buildings:
- These buildings may be more than 100 feet wide (and may have columns added to support the center sections of the arches) and hundreds of feet long.
- Instead of automatic fire sprinkler systems, they may be divided by fire-rated partition walls into sections small enough that sprinklers are not required by code. Or, they may be a single open space filled with manufacturing equipment, warehoused material, or merchandise for sale on shelves and display racks.
- The plastic face on the insulation used on the walls and roof will burn, even if it is manufactured with a flame retardant. The adhesive used as a binder in the insulation batts may be combustible, even though the glass fibers are not.
- Roof ventilation is a very high-risk activity, because of the light weight of the roofing material and its supports; the size of the roof; the wide spacing of the roof supports; and the possible weakening of the roof structure from the heat of the fire. Most aerial devices will not reach the best locations for vertical ventilation. A 16-foot roof ladder is not a good choice when the ridge is 50 feet from the eaves.
- If the roof has plastic skylights, let these melt and vent the structure for you. If there are no skylights, cut a ventilation opening in the wall just below the eaves or in the end wall just below the ridge. This will be almost as effective and a safer operation for firefighters. Use of overhead and loading-dock doors may also be effective.
- Note that the ribs or standing seams in the roof panels are part of the structural support for the roof; cutting any of these seriously weakens the roof and can cause a catastrophic collapse if anyone is standing on it.
- If fire extends to the inside of a double-faced insulated wall panel, cool the face of the panel to knock down the fire. Then open one face of the panel to ensure that the fire is completely extinguished.
• Although the thin sheet metal of these buildings can be cut with hand tools, use a power saw. It cuts faster and with less effort—especially on the new-style double-faced insulated wall panels.
For more information on these and other types of engineered steel buildings, search the Internet for “engineered steel buildings” and “pre-engineered steel buildings.”
Gregory Havel is a member of the Burlington (WI) Fire Department; a retired deputy chief and training officer; and a 30-year veteran of the fire service. He is a Wisconsin-certified fire instructor II and fire officer II, an adjunct instructor in fire service programs at Gateway Technical College, and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 30 years of experience in facilities management and building construction; and has presented classes at FDIC.
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Subjects: Building construction for firefighters
