Samiksha Jaiswal (Editor)


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A firestop is a fire protection system made of various components used to seal openings and joints in fire-resistance rated wall or floor assemblies. For penetrating cables, these can also be called as Multi Cable Transits (MCTs). Firestops are designed to restore the continuous fire-resistance of wall or floor assemblies, impeding the spread of fire by filling the openings in them with fire-resistant materials.



A firestop is a fire protection system made of various components used to seal openings and joints in fire-resistance rated wall or floor assemblies. Firestops are designed to restore the fire-resistance of wall or floor assemblies, impeding the spread of fire by filling the openings with fire-resistant materials. Unprotected openings in fire separations cancel out the fire-resistance ratings of the fire separations, allowing the spread of fire, usually past the limits of the fire safety plan of a building.

Opening types

There are a number of openings with which firestoppage is concerned.

  • Electrical through-penetrations
  • Mechanical through-penetrations
  • Structural through-penetrations
  • Unpenetrated openings (openings for future use for example)
  • Re-entries of existing firestops
  • Control or sway joints within fire-resistance rated wall or floor assemblies
  • Junctions between fire-resistance rated wall or floor assemblies
  • "Head-of-wall" (HOW) joints, where non-loadbearing wall assemblies meet floor assemblies
  • Materials

    Firestop components include intumescents, cementitious mortars, silicone, firestop pillows, mineral fibers, and rubber compounds.


    Firestops should be maintained in accordance with the listing, approval use, and compliance. Construction documentation sometimes includes an inventory of all firestops in a building, with drawings indicating location and the certification listings of each firestop. Using this, a building owner can meet the requirements of the fire code related to fire barriers during the period of building occupation. Otherwise, improper repairs may result, which would violate the fire code, and could allow a fire to travel between areas intended by code to be separated during a fire event.


    It is often necessary to install new electrical cables or mechanical systems piping through a hole in a fire rated barrier which has been properly fire stopped during initial construction, in which case the firestops are referred to as being "re-entered". In order to maintain the intent of the original fire protection plan of a building, firestops re-entries must be performed in compliance with the certification listing upon which the original installed configuration was based.

    Work sequencing with spray fireproofing

    Spray fireproofing of structural steel is most efficiently accomplished before interior partitions are built, otherwise a conflict with fire stops in firewalls could result. Firestops must adhere to the bare, dry, unobstructed surfaces of the fire barrier which is penetrated (e.g., metal decking), or adjacent to an interface of two fire barriers at which fire stopping is required (e.g., beams). Spray fireproofing cannot be applied prior to fire stopping at these surfaces, as the fireproofing would obstruct adherence of the fire stop materials to the fire barrier surfaces. Spraying the upper room perimeter with fireproofing may also result in covering of wall/ceiling joints and through penetrations that require fire stopping. These joints are then not visually observed and not provided with proper fire stopping, violating the fire integrity of the passive fire barrier.

    Proper maintenance is enhanced by the installation of tags on each side of the firestop, containing the information necessary to reference to documents indicating the approved procedures for the original installation and re-entries. This requires knowledge of the exact certification listing that was used for each opening, be it a building joint or a penetrant through-penetration seal.


    The materials used in firestops do not have ratings on their own. Firestops achieve a fire rating by combining certain materials in an arrangement specific to the item (a pipe or cable for example) penetrating the fire rated wall or floor, and the construction arrangement of the fire rated wall or floor itself. For instance, a two-hour rated pipe penetration firestop may consist of a layer of caulking over packed rockwool. This overall arrangement provides the two-hour rating, not the caulking. However, both the individual firestop materials and the overall firestop assembly are 'listed' per listing and approval use and compliance.

    Testing and certification

    Acceptable certification listings include but are not limited to those available from

  • Underwriters Laboratories,
  • Underwriters Laboratories of Canada in North America,
  • Deutsches Intitut f├╝r Bautechnik in Germany, or
  • Efectis in The Netherlands, France, Norway.
  • FM Global also provides testing and certification of firestops, and the certification of firestop contractors
  • Regulations and compliance

    When the installed configuration does not comply with the appropriate certification listing, the fire-resistance rating may be lower than expected. In those cases in which it is difficult to assess the impact, it often must be assumed to be zero: The fire protection plan for the building is compromised. It is, therefore, necessary to be able to match each opening in fire-resistance rated wall or floor in a building with a certification listing. There are thousands of listings by various certification and testing laboratories. Both the Canadian and United States Underwriters Laboratories publish books containing just their own listings, including only those firestop manufacturers who have contracted with them for testing and certification.

    Firestops should be routinely inspected and maintained to mitigate the effects of time and re-entries.

    North America

    In North American unionized construction sites, firestopping is often performed by members of the insulating trades. Insulators are the only building trade that includes firestop installation, theory and practical firestop training within its apprenticeship program.

    An agreement exists between insulators and IBEW electricians which assigns firestop work from electricians to insulators, except that composite crews are required when working near live electrical conductors, whereby an electrician is required to observe and ensure the safety of the insulator.


    Germany's GBA (G├╝tegemeinschaft Brandschutz im Ausbau) also offers a passive fire protection course, resulting in a certificate designation "Brandschutzfachkraft" (Passive Fire Protection Expert). In Europe as well as North America, all major firestop installers with nuclear installation experience are, by background, insulators first. The generic material types used and the skill sets needed between insulation and firestop installations are similar. Exceptions to the rule of thumb about firestopping being insulators' work, includes firestop devices that become an integral part of the plumbing system, which must be installed by plumbers during the forming of concrete.

    Examples of fire barrier penetrations without firestopping

    Older buildings often have no firestops at all. In such cases, a thorough inspection can identify all vertical and horizontal fire barriers and their fire ratings. A thorough inspection can also identify all breaches in these barriers, which can be sealed via approved methods.

    Non-listed firestop attempts

    Firestops created by contractors or building maintenance personnel which are not listed are sometimes referred to as "deemed-to-comply," and are not credited with adequate fire resistance rating for building code compliance purposes. These are usually short-term cost-cutting measures at the expense of fire safety and code compliance. Common mistakes include citing a listing for products that may be for other uses. For instance, an insulation with an active listing for having a certain flamespread rating does not mean it is acceptable for firestopping purposes.


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