Fire stopping materials are used to retain the integrity of fire rated construction by maintaining an effective barrier against the spread of flame, smoke, and hot gases through penetrations in fire rated walls and floor assemblies.
Penetrations in walls, floors, roofs or fire rated duct enclosures consist of materials and/or equipment passing through the barrier usually involving a closed system. Penetrations are generally smaller than openings, and the space around the penetration must be sealed with an insulating (fire-stopping) material and/or be completely cut off via a damper in order to prevent the passage of smoke, heat, and fire. Penetrations include electrical conduit, duct work, cable trays, sprinkler piping and steam pipes. Furthermore, the intersection where two fire-rated assemblies meet also creates a joint through which fire can spread.
As with openings, the fewer the penetrations in a fire wall, the greater the reliability. While electrical, plumbing and mechanical systems are needed in building construction, it is necessary to pass these systems through fire walls, hourly fire-resistive floors or wall assemblies. Openings are typically cut or drilled through the floor or walls to install the penetrating item.
Unfortunately, this process almost always leaves an opening or annular space through which smoke or fire can spread. Firestopping materials installed within the opening and around the penetrant item can help prevent the passage of flame through. NFPA 101 (Life Safety Code), NFPA 70 (National Electric Code), the International Mechanical Code (IMC), FM Global Data Sheets (1-20, 1-23, 1-24, 1-45, 7-32, 7-78, 7-83) and the International Plumbing Code (IPC) include provisions related to protection of penetrations. The codes also have requirements for inspection of firestop systems before they are concealed.
According to Chapter 7 of the 2015 International Building Code (IBC), noncombustible penetrating items shall not connect to combustible materials beyond the point of firestopping unless it can be demonstrated that the fire-resistance integrity of the horizontal assembly is maintained. Sprayed fire-resistant materials (SFRM) used during constructions should be consistent with the fire-resistance rating and the listing, including the minimum thickness and dry density of the applied SFRM, method of application, substrate surface conditions and the use of bonding adhesives, sealants or reinforcing. Noncombustible penetrating items that connect not more than three stories are permitted, provided that the annular space is filled to resist the free passage of flame and the products of combustion with an approved noncombustible material or with a fill, void or cavity material that is tested and classified for use in through-penetration firestop systems.
Penetrating items that connect not more than two stories are permitted, provided that the annular space is filled with an approved material to resist the free passage of flame and the products of combustion. Through penetrations should be protected by an approved firestop system that is installed and tested in accordance with the American Society of Testing Materials (ASTM E814) or the Underwriters Laboratories (UL 1479).
According with NFPA 101, each exterior wall of frame construction and all interior stud partitions should be firestopped to cut off all concealed draft openings using wood not less than 2 in. thick or noncombustible material horizontally, vertically, between any cellar or basement and the first floor.
On-site inspection of firestopping is critical in maintaining the integrity of any vertical or horizontal fire barrier. ASTM E 2393, Standard Practice for On-Site Inspection of Installed Fire Resistive Joint Systems and Perimeter Fire Barriers, provides guidance for the inspection of fire-resistive joints and perimeter fire barrier joint systems tested in accordance with the requirements of ASTM E 1966, Standard Test Method for Fire-Resistive Joint Systems, or with ANSI/UL 2079, Standard for Tests for Fire Resistance of Building Joint Systems. These standards would allow proper inspections of through-penetration firestops, joints, and perimeter fire barrier systems. ASTME 2393 contains a standardized report format, which would lead to greater consistency for inspections.
According to FM Global Data Sheet 1-20, Protection against Exterior Fire Exposure, openings in exterior walls designed for exposure protection should be sealed and protected. All penetrations in fire barriers should be sealed with an FM Approved wall penetration fire stop that has a fire resistance rating equal to or greater than that of the barrier. According to FM Global Data Sheets 1-23, Fire Barriers and Protection of Openings, penetrations should enhance or at least maintain the integrity of the barrier, not reduce it. In addition to Data Sheet 1-23, air-handling ducts and pneumatic conveyors should be protected in accordance with Data Sheet 1-45, Air Conditioning and Ventilating Systems, and Data Sheet 7-78, Industrial Exhaust Systems.
Since fire doors or water spray will not normally prevent the spread of flammable liquid or other flowing material through an opening in a fire wall, provide curbs, ramps, and/or drainage trenches at openings in the room to prevent the passage of liquid whenever fire barriers are used to separate occupancies containing flammable liquids. (See Data Sheets 1-24, Protection against Liquid Damage, 7-32, Ignitable Liquid Operations, and 7-83, Drainage Systems for Ignitable Liquids).
Below are the definition of some terminologies used by Nationally Recognized Testing Laboratories (NRTL).
Fire compartment: The space bounded by exterior walls or fire barriers, fire partitions, or horizontal fire-rated assemblies (floors or floor-ceiling assemblies). Penetrations are sealed and openings are protected with fire stops and self-closing or normally closed fire doors having the appropriate fire-resistance rating. When a floor/ceiling is used to provide compartmentation or segregation of hazardous occupancies it should have a minimum one-hour fire-resistance rating.
Fire partition: A vertical fire barrier that is a fire-rated assembly designed to restrict the spread of fire in which openings are protected.
Fire subdivision: The space bounded by exterior walls or fire barriers, fire partitions, or horizontal fire-rated assemblies (floors or floor-ceiling assemblies) with a minimum two-hour fire resistance rating. Penetrations are sealed with fire stops and openings are protected with self-closing or normally closed fire doors having the appropriate fire-resistance rating.
Fire wall: A vertical fire barrier that is a fire-rated wall designed to restrict the spread of fire in which continuity is maintained, openings are protected and penetrations sealed.
Risk Logic can help in determining the appropriate material to use in order to maintain and/or increase the integrity of the wall separations and mitigate the potential of fire spreading beyond its originating area.