Firestop

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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 and/or floor assemblies. For penetrating cables, these can also be called as Multi Cable Transits (MCTs).

Firestops are designed to restore the fire-resistance ratings of wall and/or floor assemblies by 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

  • 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
  • Test in flight.jpg

    Fire test of mortar based firestop

  • Mechanical pipe with metallic piping through-penetrations in a 2-hour concrete floor slab

  • Inadequate attempt at firestop using rockwool alone

  • Typical construction drawing of a firestop

  • Firestop mortar seal of an electrical cable tray

Materials

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

Maintenance

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.

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.

  • Unsealed pipe penetration in two-hour fire-resistance rated concrete block wall.

  • Improper breach of fire-resistance rated drywall assembly.

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.

  • Polyurethane foam used to fill a cable tray penetration. At Browns Ferry Nuclear Power Plant in northern Alabama, a seal of this nature resulted in significant fire losses.

  • Common concrete with no testing intended for certification listing is not a proper firestop.

  • Stuffed fiberglass weatherproofing would rapidly melt and fall out in a fire.

  • Rock wool weatherproofing is not approved for this application as a stand-alone firestop.

  • Example of how spray fireproofing was improperly used to cover penetrations.

Re-entry

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.

  • Re-entered firestop mortar

  • Re-entered opening that was created for future use in an electrical service room.

Work sequencing with spray fireproofing

Lua error in package.lua at line 80: module 'strict' not found. 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.

Fireproofing sequencing issue affecting firestopping.

Tagging

  • Firestop tag front. This identifies information necessary for proper maintenance.

  • Firestop tag back, which allows for keeping track of maintenance.

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.

Ratings

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

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.

Trade jurisdiction

North America

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

An agreement exists between insulators and IBEW electricians which assigns firestop work from electricians to insulators[citation needed], 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

Germany's GBA (Gütegemeinschaft 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[citation needed]. 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.

See also

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References

  1. ↑ http://www.fmglobal.com/assets/pdf/fmapprovals/4991.pdf Approval Standard for Approval of Firestop Contractors, Class Number 4991

External links

no:Skott pl:Gródź sv:Vattentätt skott

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