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The first step is to identify the occupant characteristics of the building. A design for fire safety may include various options. •. Evacuating occupants.
Typology: Lecture notes
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INTRODUCTION TO FIRE INSPECTION PRINCIPLES AND PRACTICES
TERMINAL OBJECTIVES
The students will be able to:
_1. Identify basic types of construction.
ENABLING OBJECTIVES
The students will:
_1. Identify the types of buildings that contain the construction types.
The model building codes and NFPA 220, Standard on Types of Building Construction , provide five major types of building construction classifications.
Noncombustible Protected (Type I)
In this type of construction the structural elements consist of noncombustible materials, usually steel or concrete, that afford a fire resistance rating that provides a given fire protection performance endurance against the effects of fire. These specific ratings are determined by the model building codes for a specific type of construction. These specific ratings apply to the roof and floor assemblies as well as any exterior or interior bearing support walls. Interior partitions are required to be constructed with approved noncombustible materials. The fire resistance ratings are provided by different designs that meet minimum performances.
Encasement with Concrete
Encasement with Gypsum Board
Spray-on Applied Coating
Figure 1 Examples of Fire Resistance Design Methods
Structural elements are entirely of noncombustible or limited combustible materials. Totally noncombustible refers only to structural materials, not to interior finish and contents. Wall enclosures may be masonry, steel, aluminum, glass, or other material. Once wall coverings are in place, it may be difficult to determine if structural elements are exposed or protected.
Noncombustible Unprotected (Type II)
The same requirements that apply to noncombustible Type I construction also apply to this type of construction, with one basic difference. This type of construction may not afford any fire-resistance rating for the exposed structural elements. If any fire protection of the structural elements is provided, it is at a lesser rating than that required for Type I construction. In this type of building the structural elements are usually made of steel, bolted, riveted, or welded together. This type of construction is susceptible to expansion, distortion, or relaxation of the steel members, resulting in early collapse during a fire. Again, interior partitions are required to be constructed with noncombustible or approved limited combustible materials.
Figure 2 Noncombustible Unprotected
Combustible/Noncombustible (Type III)
In this construction type all or part of the interior structural elements may be combustible. Exterior walls are required to be constructed with noncombustible materials. They can have a fire-resistance rating, depending upon the horizontal separation and whether they are bearing or nonbearing walls. This category usually is divided into protected and unprotected subtypes. The building will have masonry exterior walls (usually brick), and wooden structural members and combustible interior construction. The building generally will not exceed six stories, and most often will be two or three stories in height; it is often called "Main Street
This is often laminated or solid wood beams.
Figure 4 Heavy Timber
Combustible (Type V)
This type of construction uses structural members entirely of combustible materials, usually wood, and is divided into two subgroups:
Walls, floors, and roof structure are usually wood frame using different construction methods. Post-and-beam construction has a wood frame of substantial dimension and is sided with a lightweight covering such as wood boards, or plywood covered with aluminum or PVC siding. This type of construction is commonly used for barns, sheds, and other storage buildings but also may occur in dwellings and other occupancies.
In balloon frame construction, studs run from the foundation to the attic. This type of construction was common in many parts of the country until the late 1930s for residential and light commercial buildings. This provides a continuous air space from top to bottom. Floor joists are tied into the wall, allowing for fire extension in any direction. Firestopping was not a common practice.
In platform frame construction the walls of each successive story are built on a platform formed by the preceding floor. The joists for the deck may be full-dimension lumber or lightweight materials. Once the floor or
deck is in place, walls are placed on it with a sill at the bottom of the wall and a plate at the top. Platform frame construction provides a natural fire barrier for vertical extension within the walls, but openings in walls for water, sewer, ventilation, or heating/air conditioning pipes can create a void for fire extension.
This type may or may not have veneer finish.
Figure 5 Combustible (Frame)
Building subsystems provide for the practical use of a structure. These components include electrical, heating, ventilating, and air conditioning (HVAC), plumbing, and transportation.
A basic knowledge of these subsystems and their relationship to the structure helps to understand how they may affect fire safety. These subsystems may be considered separately, but it must be understood that each subsystem is only one part of the total building system.
Electrical Systems
If properly designed, installed, and maintained, electrical systems are both convenient and safe; otherwise they may cause both fire and injury. When an electric circuit carrying current is interrupted intentionally or unintentionally, arcing or heating results. Fire protection standards are requirements intended to prevent arcing and overheating or accidental contact, which may cause electric shock.
Just as structures fall into categories based on their construction, they also fall into classes based on their use. We need to look briefly at eight or nine of the more common occupancy classifications with which an inspector is likely to deal.
Assembly
Assembly occupancies generally are easy to identify because they are places we go for entertainment, dining, instruction, and worship. They fall into many different uses under most of the codes used today. The fire inspector first must be able to identify that the building is classified as an assembly, then determine the building use and the capacity of the building.
To identify an assembly occupancy properly, look at how it is used. Such occupancies include churches, auditoriums, nightclubs, restaurants, movie theaters, coliseums, gymnasiums, etc.
The capacity (occupant load) also will greatly affect the requirements for an assembly occupancy within the various code organizations. A building's capacity and use will greatly affect minimum fire safety requirements. A general grouping used is 50 to 300, 301 to 1,000, and over 1,000 capacity. These groupings may vary with the different code organizations.
For the beginning inspector, simply walking into the building and looking at the posted occupant load can be the easiest way to make the determination. When there is no posted occupant load sign, the seating system, number of exit doors, its ordinary use, as well as the inspector's knowledge of the building will help in making this determination.
Mercantile
Mercantile structures are some of the most common occupancies in many communities. These are places we go to spend our money. There is a display of merchandise for sale. Department stores, grocery stores, portions of shopping centers, and any other place designed for the display and sale of merchandise are examples of mercantile occupancies.
Storage
Storage occupancies are structures used for providing shelter for goods, merchandise, products, vehicles, or even animals.
It is simple to identify most storage facilities because of their basic use. Some structures included in this group are warehouses for most goods, barns, hangars (storage only, no work performed), bulk oil storage buildings, parking garages (no work performed), cold storage warehouses (freezers), truck terminals, grain elevators, etc.
Storage occupancies simply are storage facilities and are used in connection with most occupancies. All occupancies will have storage areas or rooms connected to them, or even inside them. A janitorial closet in an assembly occupancy would be called a storage room, but the primary use of the building would not be called storage. Likewise, most department stores classified as mercantile would have a large storage area away from the sales floor where merchandise is prepared for sale and stored until it is needed. But, again, this does not change the overall occupancy.
Storage occupancies are unique because they often are repositories for various types of commodities; this can create many types of hazards or mixes of different hazards. It is for the inspector to determine what the storage contains and the method of storage.
Health Care
It sometimes is confusing to fire inspectors to classify a building in the health care category. Nursing homes, hospitals, limited care facilities, and ambulatory health care centers are easy to classify.
The doctor's or dentist's small office used primarily for diagnostic and simple medical care would be classified as a business occupancy even though it might seem appropriate to classify it as health care.
Medical facilities where outpatient care is the primary function, and practices where other than simple diagnostic functions are performed, would be classified as health care.
Industrial or Manufacturing
This occupancy classification includes many facilities that are designed for the manufacture of a specific product. Also included are those facilities that are involved in the repair or servicing of vehicles, airplanes, boats, etc. Dry cleaning plants, laundromats, post offices, sawmills, food processing plants, gas plants, etc., also are included in this occupancy.
Special Occupancies
Some structures will not fit any of the above-listed specifications for classification. These include open structures, towers, underground structures, vehicles, vessels, water-surrounded structures, and even windowless buildings. The inspector can see that these occupancies all tend to be very difficult to inspect and will cause him/her to check the codes to help know the exact occupancy classification.
Knowledge of buildings, their construction, and their classification is necessary to protect the lives and property of the public. This knowledge also is necessary to allow firefighters to control fires efficiently and effectively. Inspection of buildings to maintain built-in fire protection is essential.
By looking at all of the various classifications, the inspector can see the importance of knowing the proper occupancy classification. Each of the model codes in use today (and some special codes that local jurisdictions and governments have adopted) also will require that occupancy classification of the structure be done before the inspector can know which code section to apply to achieve life safety.
Small Group
Scenario 1
The structure is a storage barn, approximately 30' by 30'. It was constructed in 1934 with materials and techniques appropriate for that time. The barn currently is used for storage of fertilizer, seed, and pesticides.
Questions
Scenario 2
The grocery store was constructed in 1976 and is 250' by 350' with an attached loading dock. The building has the typical fixtures and equipment expected for a full-service grocery store.
Questions
