FIRE PROTECTION IN COVERED MALLS
FIRE PREVENTION BUREAU
With the trend in the 1970s toward newly enclosed shopping malls came concerns over fire protection. A primary concern was the exposure of large amounts of people to a single fire incident as well as the unprotected vertical and horizontal openings so characteristic of these open and airy covered mall.
The realization of these fire safety issues brought changes to the model building and fire codes. These code provisions, adopted during the early 1980s, attempted to ensure a reasonable amount of time to exit a covered mall building in the event of a fire.
BUILDING CODE REQUIREMENTS
To understand the regulations that govern covered mall buildings, let’s review some code terms and definitions.
Covered mall building. According to the three model building codes— the 1988 Uniform Building Code, the 1987 National Building Code, and the 1988 Standard Building Code-a covered mall building is a “single building enclosing a number of tenants and occupancies such as retail stores, drinking and dining establishments. entertainment and amusement facilities, offices and other similar uses wherein two or more tenants have a main entrance into one or more malls.” Note that a covered mall building can include similar uses other than retail stores.
(Photos by author.)
The Standard Building Code and Uniform Building Code permit accessory uses (as opposed to similar uses) of the assembly, educational, and residential types in addition to the retail store/similar use. These accessory uses are permitted provided that they do not exceed 25 percent of the gross leasable area as well as some other specific area limitations. The National Building Code does not address this issue.
Covered mall. A covered mall is simply the roofed or covered common pedestrian area within a covered mall building that gives access to two or more tenants and may have a maximum of three levels open to each other. This portion of the building generates the majority of fire protection concerns.
Anchor store. An anchor store is a department store that is attached to but not part of a covered mall building. While the opening between the anchor store and the covered mall is not required to be protected, the anchor store’s exits must be independent of the covered mall building.
Gross leasable area. I’his is the square-foot area occupied by tenants and other “exclusive” (rentable) areas.
BUILDING CONSTRUCTION
The three model building codes are fairly diverse in their requirements for covered mall buildings in terms of building construction (the materials and methods used to build the structures).
Under the Uniform Building Code, the covered mall building may be of any type construction permitted under that code, including wood-frame construction. For three-story malls, however, this code requires a minimum of noncombustible, one-hour rated construction. Provided that a 60-foot yard (an open area with no structures) is maintained around the covered mall building and any attached anchor stores or parking garages, the allowable area (square-foot size) of the building is not limited. Anchor stores must follow the “generic” construction type, area, and height limitations found in the beginning chapters of this code. The anchor store must stand “on its own” with respect to these construction requirements.
The Standard Building Code allows unlimited-area covered mall buildings including anchor stores provided that a 60-foot permanent open space surrounds them. It limits the construction to type I, II, III, or IV (fireresistive, noncombustible, or heavy timber) for the covered mall and anchor stores. This code does not address parking garages attached to the covered mall building.
The National Building Code requires type 1, 2, or 4 construction (fire-resistive, noncombustible, or heavy timber) for the covered mall building and anchor stores. Unlimited-area covered malls apparently are permitted without the 60-foot open yards specified in the other two model codes. Floor-ceiling assemblies and their supporting columns and beams in multilevel malls are to be of onehour noncombustible construction or type 4 construction. Most anchor stores must have smoke control protection and be treated as a “tenant” zone with regard to the smoke control design. This code also does not address attached parking structures.
In terms of tenant separations, the Uniform and National building codes are fairly consistent in their requirements. In an attempt to limit the spread of fire from one tenant to another and to aid the smoke control system, these codes require a onehour separation between tenants. These walls may terminate at the bottom of a nonrated floor/ceiling or roof/ceiling assembly if these assemblies are not part of an occupancy separation (separation for different types of tenants such as an assembly use and a retail store), a fire-resistive rated assembly due to “rated” construction (the structure is of one-hour or better construction throughout), or a smoke control zone.
The Standard Building Code is more restrictive: The one-hour separation must run from the floor to the floor deck or roof deck above. Separations between different types of occupancies (accessory uses) of the assembly, residential, or educational type require a minimum one-hour rating.
All three model codes permit a nonrated and unprotected separation between the tenant space and the covered mall itself.
Under the three model codes, plastic signs, when installed in front of tenant spaces, must not exceed 20 percent of the wall area facing the mall. In addition, individual signs must not exceed a height of 36 inches (vertical signs may be a maximum of 96 inches high and 36 inches wide). The signs must be no closer than 18 inches to the next tenant and their edges and backs must be fully encased in metal.
FIRE PROTECTION SYSTEMS
The requirement of a complete, automatic sprinkler system throughout the covered mall building allows the mall to maintain its open and airy nature. The importance of this protective system to the safety of the structure’s occupants cannot be overstated.
The National and Uniform building codes require separate sprinkler systems for the mall and the tenant spaces to create two “zones”—a mall zone and a tenant zone. The codes do, however, allow a single system with separate control of each zone—essentially a means of shutting down the mall protection without shutting down the tenant protection, or vice versa. All control valves must be electronically supervised at a constantly attended location or central station.
A typical sprinkler design includes one riser for the covered mall and another for the tenant spaces. The tenant space system has a supply main coming from the riser that runs along the front of the tenant spaces above the ceiling. This tenant supply main has outlets (taps) on approximately 10-foot centers so that as individual tenant spaces are finished out, the sprinkler branch lines can be added and run into each space.
The subject of sprinklers in unleased areas often conies up. Mall managers may argue that the unleased areas will not be used for storage or any other purpose. In the case of a new mall, managers request that sprinklers not be required in the space until a tenant moves in; in the case of an existing mall, they request that the sprinklers be left as is—very often sprinkler heads on drops five feet below the floor/roof deck and with no ceiling at the heads. In my opinion, the often-requested “heat collectors” (pie plates above each dropped head) do not work in this situation and are not code-compliant.
My experience has been that to allow such requests becomes an enforcement nightmare. Mall managers soon forget about their agreements and the combustibles start moving into the unleased areas. These spaces become the perfect storage place for seasonal decorations—Santa’s house, Easter Bunny costumes, and so on. They also become smokers’ and lover’s lane hangouts for mall workers. 1 once found someone smoking marijuana in one of these spaces during an inspection—much to the manager’s dismay.
During sprinkler plan review, ensure that the designer takes into account the architectural features of the mall—peaked ceilings, overhangs, and so on. Proper sprinkler coverage is important, and the design must follow the specific sections of NFPA 13 that pertain to these features.
A final note about sprinklers: Very often the sprinkler contractor installing the “base” sprinkler system will install the tenant riser and supply mains and leave blanks (pancakes) in the outlets (taps). This way the tenant system can be put into operation and can only be shut down when an individual tenant needs to “hook into” the tenant supply main. It is crucial that these blanks be removed after the tenant space has been hydrostatically tested and is ready to be hooked up to the tenant system’s supply main.
Another important fire protection feature in the covered mall building is the requirement for a standpipe system. A Class I system (fire department use, 2 1/2-inch hose valves only) is specified.
Since covered malls typically are long, narrow structures, the codes have attempted to require placement of the hose valves to minimize hose stretches. The 2 1/2-inch hose valves are required at each main entrance to the mall, at the entry points of exit corridors/passageways into the mall, and at the landings in stairwells opening into the mall. Even with these hose valve locations, it is still a good idea for engine companies to have a prepacked “mall pack” available for deployment and to reach all portions of the building.
Under the Uniform Building Code, no substantial water supply is required for the standpipe system (it is assumed the fire department connection will be used). Only a fill connection in the form of a small supply pipe to the sprinkler system or a one-inch pipe from the domestic water supply is required in covered mall buildings more than 50,000 square feet in size. This fin connection eliminates the charging time in larger systems. However, the standpipe system must be sized to deliver 250 gpm at the hose valves. Pipe sizing (large) must reflect this requirement.
The National and Standard building codes require that a standpipe system be “capable” of supplying 250 gpm at the hose valves. It is not clear what amount of water supply is required by this specification (just charged with water in the pipes?).
Although not required by code, it is a good idea when tapping a sprinkler system for the supply to a hose valve to use an adjacent sprinkler system covering another part of the building. This way the sprinkler system in the fire area may be shut down without shutting down the hose valves.
According to the Uniform Building Code, if the area of a covered mall building is in excess of 50,000 square feet, a public address system and standby power system are required. The Standard and National building codes do not require these systems (the Standard Building Code requires that if a public address system is present, it must be accessible to the fire department). It can be used to direct the occupants of a mall. If such a system is present in a smaller covered mall building, it still must be readily accessible to the fire department.
The Uniform Building Code specifies that the standby power system must provide power for the emergency lighting, exit signs, public address system, smoke control activation systems (smoke detectors, water flow switches), and four adjacent smoke systems acting simultaneously.
An automatic smoke control system (with manual control capability) must be provided for the covered mall building. With the intent of maintaining a clear exit path and limiting smoke spread, the smoke control system, along with the automatic sprinkler system, is essential.
Detailed and somewhat complex requirements for the smoke control system are found in both the Uniform and National building codes. The Standard Building Code, while requiring a smoke control system that provides for a clear means of egress, does not mention smoke control system design criteria. The following smoke control requirements are based on both the Uniform and National building codes.
The smoke control system is divided into two zones—a mall zone and a tenant zone, divided along the same demarcation lines of the sprinkler system. A single smoke control zone cannot exceed the sprinkler zone (usually a maximum of 52,000 square feet) that is protecting the designated area.
Different smoke control zones (tenant to tenant or mall to mall) in large malls must be separated by a one-hour fire-resistive separation. Walls separating tenant smoke control zones from each other must extend from the floor to the roof or floor above. (This is one of the tenant separation requirements described earlier.)
Zones are necessary because of the way in which the system must react to a fire. The system will perform differently depending on the location of the fire.
A covered mall zone 600,000 cubic feet or less in volume must provide six air changes (full exhaust and replenishment of air in the space) per hour. Covered malls more than 600,000 cubic feet in volume must provide four air changes per hour. The volume of the mall is measured from the tenant space entrances to a distance of 12 feet above each pedestrian area. Inlets for the mall smoke control exhaust must be a minimum of six feet above the floor to maintain a clear means of egress for people exiting the building.
The codes require exhaust capabilities for tenant spaces but do not specify the number of air changes or the system’s size. On some designs a minimum of 0.1 cubic feet per minute per square foot of tenant space has been specified, but this may be too low in some circumstances. Very often the toilet exhaust in the washroom at the rear of the tenant space is used to exhaust the smoke.
Smoke control system activation, a very important aspect of the system design, often is overlooked. Depending on the fire’s location, the smoke control system will operate differently-
Smoke detectors are required in all return air portions (ahead of any fresh air inlets) of heating and cooling air handling systems of more than 10,000 cubic feet per minute (cfm). In addition, smoke detectors are required on the tenant side of all entrances to the mall if the tenant space has open security grilles.
Sprinkler heads, either part of a tenant zone or mall sprinkler zone, also activate the smoke control system. Through the use of strategically placed water flow switches, a sprinkler head in a tenant space will place the smoke control system into “tenant fire” mode. Conversely, a sprinkler activation in the covered mall itself will place the smoke control system into “mall fire” mode. The flow switches and corresponding downstream piping must be highlighted in pen on a set of sprinkler plans. The zoning that is shown on the sprinkler piping must match exactly the zoning that is shown on the smoke control system plans.
SMOKE CONTROL SYSTEM OPERATION
Let’s review smoke control system operation. Two different actions will take place depending on the location of the fire.
Fire in the mall zone. Fire develops in the covered mall area and is detected by mall sprinkler head activation or smoke detectors in an air-handling system that services the mall. The covered mall smoke control system goes into 100 percent exhaust (supplemental fresh air may need to be added, typically at lower parts of the mall, to force smoke up and out of the building).
The tenant space smoke control system and adjacent tenant zones stay in normal operation.
Fire in a tenant zone. Fire develops in a tenant space and is detected by a sprinkler head there, a smoke detector at the tenant space entrance to the mall, or a smoke detector in an airhandling system that serv ices the tenant space. Mall smoke control goes into 100 percent fresh air—air is forced into the mall from outside the building. The tenant zone smoke control system goes into 100 percent exhaust, and adjacent tenant zones stay in normal operation.
An important note about the exhaust and fresh air intake equipment locations: Ensure that the exhaust and intake ports are not located too close to each other. If they are too close, smoke exhausted immediately will be drawn back into the building. To ensure against this happening, go to the roof during system testing and check as the smoke is exhausted.
Manual controls are required for the smoke control equipment—the simpler the better. All of the equipment must be well identified, with labels for each switch. A sequence of operation, a simple but complete diagram of all components, and a set of instructions must be readily available at the equipment. Finally, the system must be capable of complete manual shutdown if necessary.
The building codes require that the smoke control equipment, the sprinkler system control valves, and the smoke detection and public address equipment be identified and accessible for fire department use. There must be signs on the doors to the rooms that contain this equipment. A fire control room for the equipment is desirable.
With all of these smoke control design features, it is anticipated that the means of egress will be kept clear for people to exit the building. However, it is still a complex, engineered system that must be tested. A complete and extensive test must be performed to verify the smoke control system design.
This test must be witnessed by the fire department as well as the building official. Test criteria, developed at the time of the system’s design (not the day of the test), must be implemented. Include several different tests, such as some in the mall and in representative tenant spaces. Select locations that appear to be critical (“dead air movement” areas or interfaces between different zones) and that will put the system through its paces. The agreed-on acceptance criteria must be verified.
Each water flow switch, manual control, smoke detector, damper, fan and louver, and any other smoke control system component must be tested for correct operation. Record each device tested and its performance. Watch out for incorrect zone activation (such as a mall water flow switch that places the mall into 100 percent fresh air), incorrect damper closure, and fans turning in the wrong direction.
An additional note about the smoke control system: During tenant remodeling, verify that doors to the tenant space bathroom have not been blocked if toilet exhaust is used in smoke control. Also verify that smoke detectors have been placed at the tenant space entrance if they use open-type grilles. These detectors often are forgotten.
EXITS
The means-of-egress provisions for covered mall buildings have been tailored to this environment. Because literally thousands of people are at risk, the codes have attempted to provide sufficient exits.
The calculated occupant load (number of potential occupants on which the exit widths are based) for the entire covered mall building, including tenant spaces, is based on the following criteria: With the entire gross leasable square feet measurement at hand, divide malls with gross leasable areas of 150,000 square feet or less by 30; areas between 150,001 and 350,000 square feet by 40; and areas in excess of 350,000 square feet by 50 to determine the number of occupants for the entire covered mall building. Under the Uniform Building Code, the minimum exit width in feet from the covered mall itself is determined by dividing the occupant load by 50. The National and Standard building codes use a “linear model” approach to calculate the exit width based on occupant load.
Individual tenant spaces also must have a sufficient number of exits and exit widths. Divide the square footage of the public area of the tenant space by 30 to determine its occupant load. The Uniform Building Code requires that occupant loads over 50 (75 in the Standard Building Code) be provided with two remote exits. A travel distance of more than 75 feet from the remote portion of the public area in the tenant space to the mall also requires having two exits under the Uniform and Standard building codes. The National Building Code requires that tenant space exiting comply with its generic egress requirements. None of the three model codes, it appears, allow a required second exit at the back of a tenant space to pass directly through a storeroom without the benefit of a corridor.
The covered mall must have its own compliant exits. The mall itself must total at least 20 feet of clear width, with at least 10 feet of clear width on either side of any obstructions such as kiosks (little roofed stands in the middle of the mall), vending machines, and carts and with a minimum clear height of eight feet above the floor. As a fire inspector, I know it is very difficult to maintain these widths, especially around holiday time. It is best to agree on locations for kiosks and stands with the mall management when the mall is designed. This will be especially helpful when mall management wants to add additional tables for its booming food court.
At either end of the 20-foot-minimum-wide mall, exits must be provided. “Dead end” malls (a portion of the mall where only one direction of exiting is possible) are permitted provided that they are not longer than twice the width of the mall at its narrowest portion within the dead end.
The minimum width of a mall exit is 66 inches. It probably will be wider due to the required exit width needed to accommodate the overall mall occupant load. The travel distance from any location in a mall to an exterior exit, exit passageway, horizontal exit, or exit stairwell must not exceed 200 feet. In addition, the required width (66 inches or greater, depending on the occupant load) must be maintained to the exterior of the building. Malls cannot be exited through anchor stores.
The Uniform Building Code also places a restriction on the travel distance within a tenant space to the mall or an exit passageway. It can be no greater than 200 feet.
A few more notes about exits: If a large assembly occupancy other than a dining/drinking establishment (such as a theater) is in the mall, it must be located adjacent to a principal mall entrance. At least half of the required exits from the assembly occupancy must exit the building independent of the mall, directly to the exterior.
According to the Uniform Building Code, security grilles or folding doors are permitted in the tenant spaces. They must be fully open during business hours. They may be closed only when the number of occupants is less than 10 in spaces that require one exit or when the number of occupants is less than 50 in tenant spaces that require two exits. The doors must be operable from the inside when the space is occupied and must not require special knowledge or effort to open. The sliding or rolling doors cannot compose more than 50 percent of the exits when two or more exits are required from the space.
OTHER CONCERNS
- A leasing plan must be given to the fire department and building departments. It must reflect the names and space numbers of all the tenants and be constantly updated to show current conditions in the mall.
- The tenant spaces should label their doors (either the doors into the exit passageway behind the space or the ones directly to the outside of the building) with their names and lease space numbers so the fire department can easily identify them.
- The three model fire codes also provide requirements for covered mall buildings. These codes are maintenance codes—they specify how the mall must be operated.
- Roofed kiosks must be sprinklered if the roofs exceed four feet in width.
- If gasor liquid-fueled automobiles or other vehicles are placed in the mall, they first must be defueled and the battery disconnected. Their location must be approved by the inspector.
- Very often the mall will stage shows during holidays and other times. During such shows the inspector must ensure that sufficient exits are available for all mall occupants— show viewers as well as shoppers.
- All decorations placed in the mall must be flame-retardant.
- All required exit widths must be maintained. Be wary of combustible trash loaded in the exit passageway behind the tenant spaces. Often mall workers will leave trash here to get it out of the way. Mall management must ensure against this.
- The fire code permits unleased areas to be unsprinklered provided that the space is broom-swept clean, a 1/2-inch gypsum board barrier is placed between the mall and the tenant space, the space is not used to store any combustibles, and the only doors to the space are keylocked. This is a difficult provision to enforce; it may be best to amend your code to require the sprinklers.
