Fire Research / Building Codes / Sprinklers

Construction Terminology


In fire underwriting, the types of materials used in the building and roof of the insured structure. Construction types include fire resistive, semi-fire resistive, and combustible, depending on the materials used. Other construction factors that an underwriter considers include the number of fire divisions in the building, the adequacy of electrical circuits for the occupancy, the number of stories, the building’s age, and the type of heating system. Most underwriters recognize seven classes of construction: 1. frame; 2. joisted masonry (which includes ordinary construction and mill construction); 3. incombustible; 4. masonry incombustible; 5. modified fire resistive; 6. fire resistive; 7. mixed.

Brick construction
A building or structure with 75% or more of the exterior walls made of some type of masonry material–such as brick, stone, poured concrete, hollow masonry block, etc.–is considered to be of brick construction for underwriting purposes. Walls usually must be of a minimum thickness, depending on the material used.

Brick veneer construction
A building with outside supporting walls constructed of combustible materials such as wood, and covered (faced) with a single layer of brick not exceeding a specified thickness is of brick veneer construction for underwriting purposes.

Fire resistive construction
Buildings with structural steel frame that is fireproofed with masonry, concrete, plaster, gypsum or other noncombustible material. The walls are noncombustible materials, and floors and roof are reinforced concrete or concrete on fireproofed steel deck.

Frame construction
A structure with outside support walls, roof and floors of wood or other combustible materials. The exterior walls may be covered with stucco or brick veneer and the interior walls with lath and plaster.

Joisted masonry construction
A structure with outside support walls made of incombustible masonry materials (concrete, brick, hollow concrete block, stone or tile) and a roof and floor made of combustible materials (e.g., wood). There are two sub-classes: ordinary construction and mill construction.

Masonry incombustible / noncombustible construction
A structure built with exterior walls made of masonry materials, such as adobe, concrete, stone, tile, or gypsum block. The floors and roof are noncombustible materials supported by structural steel frame. The structural steel frame is not fireproofed.

Mill construction
A type of joisted masonry construction, which is used in older factories and warehouses. A mill building is constructed of heavy timbers and masonry walls with no concealed wall spaces. It is considered a superior class of construction for fire insurance purposes.

Modified fire resistive construction
Buildings where the exterior walls, floors, and roof are constructed of masonry or fire resistant material, with a fire resistant rating of one hour or more, but less than two hours.

Buildings with structural steel framing members. Walls and roofs are usually constructed of metal panels or sandwich panels. Pre-engineered steel frame buildings are included in this class.

Ordinary construction
A type of joisted masonry construction; structures with masonry walls (brick, adobe, concrete, gypsum block, stone or tile) and wood floors and roofs that have concealed interior space. A fire spreads rapidly through this type of building.

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Sprinkler System Terminology

Automatic sprinkler system
An integrated system of underground and overhead piping connected to sprinkler heads (usually mounted in the ceiling) which are activated at a relatively low temperature (the initial stage of a fire). The sprinkler heads release a spray of water to extinguish the fire or prevent it from spreading. Insurance underwriters typically require automatic sprinkler systems in certain types of buildings or occupancies, and sprinkler water supply systems usually must be independent of normal water service to the protected building. Periodic inspection and testing of sprinklers is required. The existence of an approved sprinkler system normally reduces premiums for the insured property.

Antifreeze automatic sprinkler system
An automatic sprinkler system with pipes containing an antifreeze solution connected to a water supply. The antifreeze solution, followed by water, discharges from sprinklers opened by a fire. This type of system is used in locations subject to freezing.

Approved sprinkler system
An automatic sprinkler system installed in accordance with fire or building codes that uses the proper automatic sprinkler heads for the structure’s occupancy and construction, that has an adequate and reliable supply of water, that has been tested and shown to be in working order, and has been found acceptable to the appropriate governmental authority. Buildings protected by such systems usually qualify for discounts on their fire insurance premiums.

Automatic sprinkler clause
A provision in a property insurance policy (written on a building equipped with an automatic sprinkler system) that requires the insured to maintain the system in working order and to notify the insurer whenever the system is not operational, even when only briefly inoperative during maintenance. Coverage may be suspended if the insured fails to comply.

Cold weather valve
An automatic sprinkler system with an indicating type of control valve that controls ten or fewer sprinkler heads in a wet pipe system protecting an area subject to freezing. The valve is normally closed and the system drained during freezing weather.

Deluge automatic sprinkler system
An automatic sprinkler system where all the sprinkler heads are open and the water is held back at a main (deluge) valve. When the valve is triggered, water is discharged from all the sprinkler heads simultaneously. The triggering device is usually a heat or smoke detector. This type of system is used where it is necessary to wet down a large area quickly, such as an airplane hangar or explosives factory.

Dry pipe automatic sprinkler system
An automatic sprinkler system where all piping contains air under pressure. When a sprinkler head opens, the air is released and water flows into the system and to any open sprinkler heads. This type of system is used in areas where the sprinkler heads and the immediately adjacent piping can be exposed to freezing conditions.

Emergency impairment
All or a portion of an automatic sprinkler system that is out of service due to an unexpected occurrence, such as a ruptured pipe, opened sprinkler head, or interruption of the water supply.

Fire extinguishing system
An apparatus or system designed to cause a fire to cease burning or to quench it. Such systems include water spray, carbon dioxide, dry chemicals, halon and foam, portable or fixed fire extinguishing systems.

A nontoxic, vaporizing liquid used in fire extinguishing systems. The vapor is injected into the room, depriving the fire of oxygen. It is most often used in computer and laboratory rooms, where foam or water extinguishing systems might do irreparable damage. Although these systems are still in use, production of new halon gas was discontinued in the United States as of January 1, 1994, due to its ozone depleting effects.

Indicator valve / post indicator valve (PIV)
An automatic sprinkler system control valve that extends above the ground or through a wall for operating the sprinkler system. A target or indicator is visible through an opening in the post, which shows that the valve is open or shut.

Preplanned impairment
All or a part of an automatic sprinkler system that is out of service due to work that has been planned in advance, such as repairs to the water supply or sprinkler system piping.

Preaction automatic sprinkler system
An automatic sprinkler system that is similar to a dry-pipe system, but air pressure may or may not be used. The main sprinkler system control valve is opened by an actuating device, which permits water to flow to the individual sprinkler heads and the system then functions as a wet-pipe system. It is generally used in areas where piping systems are subject to mechanical damage and where it is important to prevent accidental discharge of water.

Present value of sprinkler reduction
A method used in risk management to evaluate the value of installing an automatic fire sprinkler system. The method compares the cost of installing the system today with the reduction in fire insurance premiums in the future. A formula is calculated to make the comparison on a present value of money basis, or on an organization’s required rate of return basis.

Present value
The value today of a future monetary sum or cash flow; the amount that, if received now and invested at an assumed rate of return, equals a given future sum. A known or assumed future amount is discounted by a stipulated rate that might be received if invested over the period of time before the money is received. Example: At an assumed investment return of 20%, the present value of $10,000 receivable in one year is $8333.

Openings in a building wall covered by hinged metal flaps that allow water to flow through, reducing the weight and preventing possible collapse. Scuppers may be put at floor level to allow water from sprinklers to flow through and may be put in parapet walls above roof level to allow rain to run off in the event the roof drains are clogged.

Sprinkler leakage coverage
Coverage of damage to a building or contents caused by leakage or discharge from an automatic sprinkler system, or caused by the fall or collapse of tanks that are part of the system. Coverage is included under the Insurance Services Office commercial property basic, broad, and special coverage forms. Many property forms exclude coverage if sprinkler leakage is caused by an earthquake or volcanic action.

Sprinkler leakage liability insurance
A liability coverage that protects the insured should a sprinkler leakage loss occur on rented premises or on premises loaned to the insured. Coverage applies when an automatic sprinkler system discharges or leaks water or other substances as the result of the insured’s negligence.

Wet pipe automatic sprinkler system
An automatic sprinkler system where all piping is filled with water under pressure and released by a fusible mechanism in the sprinkler head.

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Miscellaneous terminology

Adjacent building
A building situated very close to, but not in contact with, another building.

Adjoining building
A building that touches another building.

Class rating
A property insurance rating method where the type of building or occupancy is used to determine the rate. The rating bureau establishes rates for various building construction types (e.g., wood frame, brick, etc.) and protection classes and for occupancy by hazard categories (e.g., office, computer manufacturing, etc.). This information is published in a manual used by underwriters. If the rate classification is not listed in the manual, the risk must be specifically rated.

Fire protection
Methods of providing for fire control or fire extinguishment. Also, the prevention, detection, and extinguishment of fire.

In fire insurance underwriting, the type or character of the property and its intended use. Occupancy is an important consideration in determining both the appropriate amount of insurance and the premium rate.

Party wall / common wall
A wall shared by buildings constructed on either side of it.

The existence and nearness to an insured risk of firefighting facilities. Protection includes fire hydrants, adequacy and reliability of water supply, the number and quality of available firefighters, adequacy of equipment, etc.

Protection class
A grade assigned to a fire protection district, usually expressed in a number between 1 (best) and 10 (worst).

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