Commercial Construction Considerations: Interior Features

Fire departments should try to develop a working relationship with the facility managers of large commercial facilities in their response area.

In last month's article we looked at the building process and the building floor plan. This month we will discuss walls, doors, ceilings, flooring, and roofing.

In addition to the floor plan, the architectural portion of a building design will include wall and door types. Buildings are limited to certain fire areas; the International Building code defines a fire area as "The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or fire-resistance rated horizontal assemblies of a building." The fire area is a compartment within a building that is intended to prevent the spread of fire to outside the fire area. The fire area is determined by the occupancy of the facility and whether or not it has a sprinkler system.

There are literally hundreds of different assemblies that create the fire walls, fire barriers, exterior walls or fire-resistance rated horizontal and vertical assemblies. It is important to know what fire areas exist and how they are separated from other parts of the building.

These assemblies can range from multiple layers of gypsum board with metal studs 16 inches on center to concrete block walls. It is vital to have an idea of what may exist and how you would deal with it. The location of fire areas is very important when considering vertical ventilation; if you ventilate in the wrong location you may not be providing any ventilation of the area under fire conditions.

Door Styles
Forcible entry is something we spend many hours training on, therefore knowing the types of doors that exist is very important to firefighting operations. The door assemblies, door material and construction that exist need to be known. In addition to the door construction, it is important to know what types of locking systems are in place. Knowledge of the doors and what the door frame assemblies could possibly be constructed of and the type or access control systems that may exist are also important.

Many facilities have moved away from the typical lock and key door access systems and have gone with biometrics, proximity readers, or card access systems. Doors that use these types of access control typically make use of either a magnetic lock or electric door strikes. Often there is no way to tell the difference between these and standard lock types. There is a big difference when trying to force a door with a magnetic lock compared to a traditional lock. It is also import to know of any specialty type doors that may exist, including roll-up doors, and revolving doors, and how you will deal with these obstacles when you see them.

Ceiling Types
Another important construction feature that is architectural in nature is the ceiling type. This feature will have a large impact on fire behavior and on the behavior of the structure supporting the roof or the floor above. There are generally three ceiling types:

  1. a hung lay-in type ceiling, that is one with a hanging two-by-four-foot or two-by-two-foot grid with ceiling tiles laying in the grid,
  2. a hard ceiling system, i.e. gypsum board attached to either the bottom of the structure above or a frame of some type, and
  3. no ceiling, where the occupied space is open to the structure above.

The option of no ceiling is becoming far more popular due to cost savings and the addition of volume to a space; however this type of construction leaves the building structure, including lightweight steel bar joists and engineered lumber, unprotected, which could lead to structural failure in a short period of time under normal fire conditions.

Floor Systems
The flooring system is a construction feature that I feel is important to mention. I know many of you are probably thinking, well the floor is the floor, supported by some type of structure that will be discussed later and the floor has some type of floor covering, carpet, tile, etc. Firefighters need to know that there are many types of flooring installed on top of the building structure and these include wood products such as plywood, OSB (oriented strand board), pre-cast concrete, and poured-in-place concrete.

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