“BREAD AND BUTTER”” OPERATIONS:”

BREAD AND BUTTER” OPERATIONS:

STORE FIRES,PART 1-CONSTRUCTION

Photo by author unless otheswise specified.

A quick look at any municipality’s business district will reveal stores of all shapes, sizes, and construction. To be successful when operating in these various occupancies, departments must have in place a plan (standard operating procedure) incorporating basic tactics that can be used for all store fires and yet that covers variations that may be encountered as the operation unfolds. Preplan and drill on your SOPs.

Store occupancies vary from singlestory, one-store structures to the new megamalls containing more than 100 retailers under one roof.

“MOM-AND-POP” STORES

The “mom-and-pop” store is one of the most common types of store occupancies encountered. It usually is found on the first floor of older buildings that have one or two fl(x)rs (or one floor and an attic) of apartments above. Frequently, the operators of the store live in an apartment above or behind the store.

Regardless of the type of construction used in the building in which the store is located, certain features of the store itself must be noted. Among them are the following:

  • Stores located in these older structures usually have metal ceilings that have been covered during renovations.
  • The original floors in these stores usually were made of wood. but again, renovations may have changed them. Beware of new floors of tile or even
  • concrete, which sometimes is “floated” over old floors to provide an even working surface for installing a new floor. Both types of floors dramatically increase the dead load on old floor beams, which were not designed to carry the increased weight.
  • These stores generally are small and do not carry a large inventory due to limited storage space.
  • Unless remodeled, the front door probably is wooden and can be forced easily.

One factor that distinguishes a fire in this type of store from fires in other stores is the life hazard presented by the apartments located above and behind the store.

TAXPAYERS

Another type of building found in almost every department’s response area is what today is known as a strip mall, formerly known as a “taxpayer.” l he term “taxpayer” became part of the fire service vocabulary during the early part of this century. The name was used to describe a single structure housing several individual stores sharing a common roof. The main purpose of these structures—which were constructed rapidly and cheaply—was to increase tax revenues.

Some characteristics of the early taxpayers include the following:

  • They were built entirely of wood—wooden floor beams, flooring, roof beams, decking, and partition walls—but most had exterior masonry walls.
  • l he roofs generally were tongueand-groove boards covered with tarpaper, felt, and tar.
  • A large, undivided cockloft ran the length of the building.

These construction features usually contributed to hot, smoky fires that led to the rapid, complete involvement and subsequent destruction of many of these early rows of stores.

The stores generally are only one story, but some were built with a second floor, which might house large, open-area occupancies such as dance halls and meeting rooms. In some cases, the space might be broken down into many small, separate offices and suites.

The difficulties in fighting taxpayer fires, due to their original construction features, have been exacerbated by modern renovations.The floor above the mom-and-pop store is almost certain to have a nighttime life hazard.

Many of these “rows” that did not burn down were knocked down and replaced with newer structures. Those still remaining have all of their original features and associated problems, but renovations and upgrading have made fires in these structures more difficult to manage. Drop ceilings, hidden voids, ductwork for modern heat and air-conditioning systems, and, as already mentioned, new flooring (tile, concrete) over existing wooden floors —all complicate efforts to extinguish fires in these occupancies.

FACTORS THAT AFFECT TACTICS

The age of the stores, which should be determined early in the firefighting operation, affects the tactics used to fight the fire.

Some buildings have had new facades installed to modernize the store’s appearance. Fake brick fronts of stucco (colored to look like brick) or brick veneer completely hide old wooden store fronts. When possible, look at the area at which the front wall attaches to the side w all. If the front is brick veneer instead of solid brick, all brick ends will be aligned and the side wall w ill be of a different material, such as wood, stucco, or tin. In the case of solid brick construction, the bricks at the corners tie the front and side walls together so that w hen looking at the corners, you can see the sides of the bricks in one course and the ends of the bricks in the next.

As businesses expanded, larger, undivided floor areas w ere needed. To have a completely unobstructed floor area, the supporting columns had to be eliminated. To accomplish this, trusses became the solution. One of the earliest types of trusses used, and the type most easy to identify, is the bowstring truss. Its hump-like shape, even if obscured from street level, is evident to firefighters going to the root to conduct ventilation operations. These trusses are most commonly found in supermarkets, bowling alleys, commercial garages, and other businesses requiring large, unobstructed open areas. When encountering a building with a bowstring truss roof assembly, remember that the higher the “hump” or bow, the longer the span of the truss.

Another change that has occurred in the construction of taxpayers is the addition of steel. It was introduced into store construction to support roof and floor joists. Large, unprotected steel I-beams were used to span the openings in the front walls for display windows and doorways. Other steel I-beams were used, with supporting columns or interior masonry partition walls, to span larger distances than would be possible with wooden beams. When these steel beams are exposed to the heat from a free-burning fire, the beams absorb the heat. As the steel is heated, it begins to elongate. At 1,000°F, a 100foot beam will extend 9½ inches in length. As it extends, the beam may push all or part of a wall down, or it might punch a hole through the brickwork. When the temperature of the heated beam approaches 1,500 F, the steel begins to soften and fail. As water is applied on the fire and the temperature of the steel decreases, the beam contracts to its original length. If the beam has been heated to the point where sagging occurs, the contraction of the steel as it cools may cause the beam to pull off its end supports, precipitating a partial or total collapse.

The age of a structure is not always apparent from the front. This one-story single occupancy has a modern facade that hides its true age and construction features.

Another factor that adds to the difficulty in operating at fires in these malls is their size. The use of steel in their construction has made it possible to build row’s of stores that run the length of entire city blocks. Taxpayers 200 by 100 feet in size containing up to 15 separate occupancies are not uncommon. Unfortunately for the fire service, the larger size of the buildings increases the difficulty of controlling these fires.

As do the older, smaller stores, the newer ones still have undivided cocklofts. Fire entering the void above any of the stores’ ceilings w’ould have a “lumberyard” of wood to devour. Wooden roof beams and the underside of the wooden roof deck are exposed, as is the wooden lath used to hold up the plaster ceilings and the supporting members from which the ceilings hang. Even if the cockloft at one time had been divided by partitions or a firewall, time and renovations usually have rendered them ineffective. Breaches made for modern wiring and air-conditioning and heating ducts, as well as the deterioration of mortar joints, contribute to the ineffectiveness of these old partitions.

In both the old and newer stores, basements pose extensive problems for the operating forces. Although frequently partitioned into separate storage areas, the individual store basements generally are isolated with flimsy material. Individual partition walls extend only to the ceiling, leaving a ready path for fire extension along the undivided floor joists. Many times, the cellar layout does not conform to the layout of the ground-level stores. Stores, such as supermarkets, that require large storage areas may lease space under stores that do not require storage space in addition to that available in their stores.

The bowstring truss, easily identifiable, increases unobstructed floor space. The higher the hump, the longer the span.

(Photo by Tim Klett.)

Unprotected steel I-beams support frontage so display windows can be installed. Shown here, a parapet wall resting on a steel I-beam is a collapse hazard even without fire conditions.Modern construction for large-area occupancies often employs steel-frame construction with rolling bar trusses and Q-deck roofing.A double span of wooden I-beam roof assembly members.A lumberyard in a ceiling - a lightweight wood truss loft supported by laminated beams and columns.Uncommen truss construction: chords of two 1x2s with webs of lightweight metal held together by bolts. Preplan the construction in your jurisdiction. Survey buildings-in-progress. Identify lightweight construction. Use extreme caution when operating on lightweight roof assemblies. Rapid and catastrophic failure has occurred and will occur again.

Ventilation—always a problem in cellar fires—is especially difficult in store cellars, which have high fire loads and limited natural openings. You must locate outside entrances for both ventilation and egress for handlines. Locate and open up all other openings. Be aware that any openings on the side or in the rear of a store most likely will be heavily secured to protect against burglary . Extra staffing and forcible entry equipment —in addition to the standard axe and halligan —might be needed for entry.

STRIP MALLS

The strip mall is a dressed-up, modern version of a taxpayer. Lightweight truss assemblies made of wood, steel, and combinations of both have replaced wooden roofs and floor beams. All wood roofs have been replaced with steel Q-decking covered by either gypsum planks, precast concrete planks, or wood planks. Even though these stores may be built with more “noncombustible” material, the fire load of the goods stored in them has increased. The lightweight truss assemblies used in many of these new stores are especially susceptible to collapse with only a light fire condition. Expect rapid failure of these assemblies —in less time than it takes many departments to respond, especially at night when the fire may have burned undetected for some time. Early identification of these structures, preferably while they are under construction, is the only way to be sure of the type of building in which you will be operating if fire strikes.

MEGAMALLS

Megamalls now are being built with some regularity across the country. These malls are constructed of the same materials as strip malls, but they may contain hundreds of stores. locating the fire area and gaining access to it are major concerns in these giant malls. They require individual planning based on the fire department’s capabilities and will be discussed in a future article.

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