STRIP MALLS: THE TAXPAYERS OF TODAY

STRIP MALLS: THE TAXPAYERS OF TODAY

BY GLENN P. CORBETT, P.E.

As development sprawl overtook the American suburban landscape a few decades ago, a new type of neighborhood “corner store” appeared–the strip mall. Like its urban ancestor, the taxpayer, the strip mall provided the convenience of having a variety of shops under one roof. While the taxpayer and strip mall share common construction characteristics, they also can have distinct differences that must be considered. In some cases, however, it may be difficult to distinguish between a taxpayer and a strip mall.

TAXPAYERS

Fire service legend tells us that the term “taxpayer” was developed to describe the practice of constructing “temporary” revenue-generating buildings on a tract of land along a city street. These buildings were to pay the taxes on the land until a more desirable multistory apartment or office building could be built. Whether this legend is true or not, the fact remains that thousands of taxpayers still exist in cities across America.

Taxpayers generally have the following characteristics:

They most often are of ordinary (Type III) construction, usually with brick bearing walls and wood-joist roof members.

They commonly are one story in height, although the two-story variety can be found in many jurisdictions.

Depending on the region, many taxpayers can have full or partial basements.

They usually are limited to approximately six to 10 small stores (or other commercial establishments).

They most often have common cockloft or attic spaces.

STRIP MALLS

Strip malls, on the other hand, may have the following characteristics:

They may be of noncombustible, ordinary, or even wood-frame construction (Types II, III, and V construction, respectively).

When of noncombustible construction, strip malls have exterior walls of concrete block or concrete “tilt” walls (possibly with brick veneer) with steel bar joist roof members and a metal deck supporting a built-up roof.

Contemporary ordinary construction strip malls use concrete block for exterior walls and solid wood joists or lightweight wood trusses to support a wood roof deck.

Older ordinary construction strip malls may have large bowstring trusses.

Some smaller strip malls may be built entirely of wood-frame construction.

Nearly all strip malls are one story, although a two-story strip mall occasionally may be encountered.

Again, based on region, strip malls may or may not have basements.

They usually are larger than the taxpayers and may have as many as 15 to 20 small stores and a large anchor store or two.

Strip malls have greater store depth than taxpayers. Strip mall anchor stores, such as supermarkets, may be more than 150 feet deep.

They most often have common cockloft or attic spaces.

STRIP MALL SURROUNDINGS

Another distinguishing feature of strip malls is the property surrounding them, which most often is a parking lot out front and along the “ends” and a delivery truck driveway at the rear of the building, in many cases. (Taxpayers usually cannot be accessed on all four sides.) The strip mall “set-back,” however, can be both an advantage and a disadvantage.

The parking lot can be helpful, especially from an apparatus-placement standpoint. In many cases, apparatus can be placed on four sides of the structure, and additional apparatus can be placed in close proximity in the parking lot. In some cases, a staging area can even be set up in the remote area of the parking lot, relieving the public streets of tie-ups.

Among the disadvantages of the strip mall “set-back” are the following:

On-site private hydrants must be used, since the strip mall is too far from the public hydrants surrounding the property. In some cases, the main may be six or eight inches in diameter and of the dead-end type. These private mains and appurtenances often are poorly maintained. In addition, if the building has an automatic fire sprinkler system, it very often will use this same main. It is critical that fire departments establish the supply layout (including fire department connection, tie-in location, and underground gate valves) and flow capabilities during preplanning.

The “out-of-sight” delivery truck driveway at the rear of the strip mall often is dotted with crater-size potholes that create hazards for fire apparatus. These delivery driveways also may have obstructions that can present additional hazards–for example, these areas often are used as an easement for utilities. Firefighters, therefore, must be aware that overhead power lines may be present.

Also, retail establishments often use these driveways for storing pallets, bins, bales, cardboard, and other objects and materials; and dumpsters may block access. It is best to designate these areas as fire lanes and to subsequently inspect them frequently.

OCCUPANCY TYPES

Strip malls may have a variety of tenants. In addition to the typical delicatessen, bakery, and hardware store, occupancies can include day-care centers, nightclubs, massage parlors, auto-body shops, and even storefront churches. From a building code standpoint, it`s very possible to have assembly (A); mercantile (M); business (B); and, unfortunately, hazardous (H) occupancies all in the same strip mall.

What all this means to you is that you will be confronted with a variety of hazards as well as a variety of occupancy types. Hazards can include flammable liquid storage/sales in a paint store, a dry-cleaning store using combustible Class II cleaning liquids, flammable spray operations in a body shop, and oxidizer and corrosive material storage/sales in a swimming pool supply store. Occupant count can range from dozens of young children in a day-care center to hundreds of shoppers in a supermarket to a large group of drunk patrons in a nightclub.

Most building codes require a fire-rated separation (also known as an occupancy separation) between different occupancy types (separating a business occupancy from an assembly occupancy, for example). These walls, which must completely separate the different occupancies, can be one-, two-, three-, or four-hour fire rated, depending on the type of occupancies being separated. A higher rating is required as the hazards and threat to life safety of the specific types of occupancies increase. Depending on the particular building code being applied, the installation of automatic sprinklers in the building can reduce the hourly rating (this practice is prohibited in some building codes).

What this means is that often there will be no rated separation required between a group of strip mall tenants if all are the same occupancy type. A group of small shops selling fish, greeting cards, and videocassettes requires no separation between each shop. The “demising” walls between the shops may be made of rice paper, be full of holes, and not be continuous above the ceiling as far as the building codes are concerned!

Depending on the size of the strip mall, another type of fire-rated separation–a fire wall (also know as an “area separation wall” under some building codes)–may be required. Building codes contain provisions that limit the size (area and height) of all buildings based on the type of construction and type of occupancy–the better the type of construction (fire-resistive being the best, wood-frame the worst) and the less hazardous the occupancy, the larger the building can be. When the building area becomes too large, fire walls often are required to break the structure into smaller “buildings” (fire areas).

These fire walls are a “step above” the occupancy (fire) separations described previously–they may have a two-, three-, or four-hour rating, but they also must be more substantially constructed so as to allow collapse on either side without pulling the wall down. Often, these walls also must be continuous from the foundation to above the roof line–the wall must run from “dirt to sky,” as I like to tell architects. Unfortunately, building codes grant exceptions to this continuity rule by allowing some fire walls to terminate on the underside of the roof deck.

Only on-site preplanning and review of your local building codes will untangle this mess of code requirements concerning fire-rated separations. Look above the ceilings, and ask questions of your building and fire inspectors. Know how the building will work for you and against you.

IT`S IN THE ATTIC!

Strip malls of Type III and V construction that use combustible structural roof (or floor members, in a multistory building) require the use of draftstops to compartmentalize the attic or floor void spaces. The draftstops are not required to be fire rated; they may be made of plywood or gypsum board. The intent is to have the draftstop slow the fire down and keep it confined to a given area for an indeterminate period of time. It will buy you time to get ahead of the fire if it is spreading through the attic (or floor) void space.

The requirements for the draftstops have changed over the years. Currently, draftstops are required to limit the size of attic compartments to 3,000 square feet and floor void compartments to 1,000 square feet (some building codes specify a maximum horizontal dimension of 60 feet in either direction). Again, depending on the building code, the installation of automatic sprinklers can eliminate the requirement for draftstops or allow for larger compartments (triple the size). Conduct your own research to determine what rules apply to draftstops in your jurisdiction. When properly installed and maintained, draftstops help fireground activities. However, they often are compromised by holes punched in them for electrical wiring and the like. Even though the draftstop isn`t fire rated, it must be “tight.” Perform frequent inspections and order repairs made where holes are noted.

One last note about preventing fire spread: Some building codes require firestopping at 20-foot intervals in combustible “architectural trim” (projections such as cornices, mansards, overhangs, and so on). Firestopping will help prevent the fire from doing an “end run” on the outside of the building around your fire attack. Know where the firestopping is located and how you can use it to your advantage.

STRUCTURAL FIRE RESISTANCE

As discussed previously, building codes limit the size of any building based on the type of construction and occupancy group type. One way to increase the allowable area is to increase the fire resistance of the structural members–a Type II building, for example, may use unprotected (bare) steel bar joists for the roof`s structure. “Fireproofing” the steel by applying a fire-resistive coating can increase the allowable area. Doing this may be necessary to permit certain occupancy types into the building. Probably the most common example is a place of assembly, especially a nightclub. Nightclubs of substantial size usually require a higher level of structural fire resistance to remain within the building code`s allowable area limitations. It also may be the only occupancy within the building to have fireproofing; surrounding tenant spaces may have no structural protection.

During preplanning visits, look at the structural members in each occupancy. Note which members are protected and which are not. Note these facts in your preplan to establish where this structural protection will help your attack.

SPRINKLER SYSTEMS

Building codes don`t require automatic sprinklers specifically for strip malls. However, they do require sprinklers for mercantile and other types of occupancies under certain conditions. Basements also have to be sprinklered in some cases. Under some building codes, sprinklers can also dramatically increase the allowable size (including area) of a building.

Looking more closely, some building codes require automatic sprinklers for “retail sales rooms” larger than 12,000 square feet. Others require sprinklers for mercantile “fire areas” larger than 12,000 square feet. Most codes, therefore, require that sprinklers be installed in large anchor stores such as supermarkets. In addition, most basements in mercantile occupancies must be sprinklered. Nightclubs larger than 5,000 square feet also are usually sprinklered. Keep in mind that only certain areas of the strip mall may be sprinklered.

While conducting a preplanning walk-through, determine the following:

the areas of the strip mall that are sprinklered; note whether the system provides complete protection (including in combustible attic spaces) or protects only certain areas.

the type of system–wet or dry (note that many strip malls with unheated attics often leave unleased tenant spaces unheated, necessitating a dry system).

the location(s) of the main riser control valve(s) (which could be hidden in the closet of a tenant space).

the location of the fire department connection and the areas of the building it supplies.

UTILITIES

Fortunately, most modern strip malls have multiple utility meters/cutoffs, one for each tenant space or group of tenant spaces. The meters/cutoffs should be identified by “suite” number (the number assigned to individual tenants). In this manner, utility service to particular tenants or areas of the mall can be shut off. Note the location of the utility meter bank in your preplan. In many cases, the meters are on the exterior of the building, although gas meters may be in the basement in some buildings.

FORCING ENTRY

Another important consideration when developing firefighting strategies for strip mall fires is how you will gain access through the front and rear doors. Each can pose problems.

Front doors usually are aluminum stile doors with glass panels. Using a “through-the-lock” entry technique usually is called for here and can be readily accomplished. In some cases, it`s what`s behind the front door–and even the large display window–that can impede access.

Electronic and computer stores and similar occupancies now are installing roll-down metal shutters, located on the inside of the store, behind the front door and display window. These shutters are secured with a padlock. What you have, then, is a “double” forcible entry situation (contrast this with the double forcible entry conducted at taxpayers where sliding gates and roll-down shutters are placed on the outside of the building). Consider the implications on ventilating the front display window, particularly how to coordinate the opening of this window with your interior attack.

The rear door of a tenant space poses an even more formidable entry problem. These doors are heavily secured to prevent break-ins and may even have drop-in metal bars. In some cases, the doors may actually be welded shut. Consider your operations for forcing these doors, including the use of metal-cutting saws. Also keep in mind that it is important to open these doors to provide a secondary means of egress for crews operating inside who are cut off from the front door. Another issue involving rear doors is identification. It`s difficult to determine which door corresponds with which tenant space without the presence of a name or suite number. During your preplanning visits, make sure the doors are identified, at least by suite number.

FIREFIGHTING CONSIDERATIONS

Fighting fires in strip malls raises many concerns. The following deserve special discussion.

Lateral fire spread throughout the strip mall is probably the greatest concern. Without the presence of fire-rated separations or draftstops that are continuous through the plenum space to the roof deck above, fire can spread readily from tenant space to tenant space. The ease with which this fire will spread depends on the construction of the roof members themselves.

A roof of solid wood joists with a dropped ceiling below will allow fire to spread in this void space. A roof structure of wood trusses creates a very large void space, a virtual lumberyard. Fire extension through the truss will be rapid.

A strip mall with steel bar joists and a built-up roof can be subject to a metal deck roof fire. This fire (in what`s classified as a noncombustible building) can spread laterally, independently of the main body of fire below. The asphalt (tar) in the built-up roof becomes heated and then ignites, spreading fire above the roof deck and dripping hot tar into the store below through the deck seams.

The key to stopping a fire from spreading through the roof area is to get ahead of it. You must pull ceilings and apply heavy streams through the openings created. Consider the time needed to gain entry into adjacent tenant spaces–where will the fire be when you gain access? Will it be past your position?

Fires in wood truss voids will spread rapidly due to the inherent openness of the truss. Consider the quick collapse potential. In a metal deck roof fire, cooling streams must be applied to the roof deck to cool the asphalt and stop the fire`s progress.

Besides assisting the interior hose teams, ventilation can help slow horizontal fire spread through the roof area. Ventilation procedures, however, still must be conducted safely in accordance with the type of roof. Firefighters operating on metal decks, for example, are in danger of falling through if the cantilevered end of the deck gives way as the vent hole is cut. The wood bowstring truss poses the danger of large area collapse.

Consider a trench cut only when the “distance for time” is in your favor. Also, don`t forget the numerous air-conditioning units and other concentrated dead loads on the roof.

And, there is the lightweight wood truss and wooden I-beam. In many cases, it is too dangerous to operate on top of or below these lightweight structural members when fire has taken possession of them.

“Taking” the front display window can provide substantial horizontal ventilation. As already mentioned, however, it must be coordinated with your interior attack.

Fires can also spread horizontally belowgrade through a basement. Many strip mall basements do not have substantial separations between occupancies, allowing the fire to move unimpeded.

Strip malls can pose some unusual problems for firefighters. Only through proper preplanning can you reduce the risk to yourself and your fellow firefighters.

Most on-site fire hydrants are owned and maintained by the mall owner. They must be inspected frequently by the fire department. Your preplanning should establish how much water is available (without stealing it from the sprinkler system).

(Left) From the front, this strip mall appears to be a modern building with a flat roof. However…a view of the rear of the building reveals a bowstring truss (right). Your preplanning sessions must include a walk around the entire building.

(Left) The relatively rare two-story strip store presents an additional problem–vertical fire spread. In addition, the second floor of this type of building usually has an entrance only at the front of each occupancy, along an open walkway. (Photo by Lynn Jennings.) (Right) Large strip centers may have dozens of occupancies, presenting a variety of hazards. The building itself can be immense, leading to our primary concern of horizontal fire spread through the structure.

(Left) Note the electrical poles, which split this rear driveway. How do they affect the positioning and use of aerial apparatus? Which electrical meter serves which tenant? (Photo by Lynn Jennings.) (Right) What is behind the open door on the right–“the lady or the tiger”? The NFPA 704 diamond on the open door (circled) indicates the presence of a hazardous material. Most hazards will not be so well identified. Note also that this door does not have any suite number or occupancy name, which makes it difficult to determine which tenant you are standing behind. (Photo by Lynn Jennings.)

This fire department connection is well identified with a red light. In addition, an experienced inspector has called for a sign identifying the location of the main riser valve, which is located at the other end of the building. The sign with the “R” in the triangle (as required by New Jersey law) indicates that this building has a truss roof.

(Top) Firefighters entering this building through the front must maintain this path of egress…there aren`t any doors at the rear–just a 30-foot drop (bottom). Accessibility is limited for this building; fortunately, most strip malls have better access than this one does.

GLENN P. CORBETT, P.E., is a professor of fire science at John Jay College in New York City, a technical editor of Fire Engineering, and a firefighter with the Waldwick (NJ) Fire Department. He previously held the position of administrator of engineering services with the San Antonio (TX) Fire Department. Corbett has a master of engineering degree in fire protection engineering from Worcester Polytechnic Institute in Massachusetts. He authored two chapters on fire prevention/protection in The Fire Chief`s Handbook, Fifth Edition (Fire Engineering Books, 1995). Corbett has been in the fire service since 1978.