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Cross-market term

Firestopping and cavity barriers

Measures closing the routes fire and smoke take through a building's concealed spaces and through the holes made in fire-resisting elements for services.
  • 4Markets
  • NoSame thing everywhere
  • 6Calculators

What it is called, by market

One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.

  • United Kingdom

    Same word, different thing

    firestopping

    also cavity barrier, fire stopping, intumescent collar, fire sleeve

    FIRESTOPPING seals a penetration through an element; a CAVITY BARRIER subdivides or closes a concealed space. Two different requirements in Approved Document B, routinely used as one word.

  • Australia

    Close, not identical

    fire stopping

    also fire collar, cavity barrier, service penetration seal

    NCC terminology closely follows the British split, with cavity barriers required in concealed spaces and tested penetration systems required at services.

  • United Statesyours

    Same word, different thing

    firestopping

    also through-penetration firestop, fireblocking, draftstopping, F rating, T rating

    FIREBLOCKING and DRAFTSTOPPING are separate code items covering concealed spaces, and they are about resisting fire SPREAD in a void rather than achieving a rated seal — closer to a cavity barrier than to a firestop.

  • Canada

    Same word, different thing

    firestopping

    also fireblocking, firestop system, F/FT rating

    As the United States, with the National Building Code separating firestopping at penetrations from fireblocking in concealed spaces.

The governing standard, by market

  • United Kingdom

    Approved Document B / BS EN 1366-3

    Fire safety including cavity barriers and the sealing of service penetrations, and fire resistance tests for penetration seals.

  • United States

    ASTM E814 (UL 1479) / IBC 714 and 718

    Through-penetration firestop systems with F and T ratings, and fireblocking and draftstopping requirements.

Calculators for this

Each works in either measurement system, and the terminology on the page follows whichever market you have selected.

Penetration Firestop Caulk Volume Calculator →Firestop Membrane Penetration Box Area Calculator →Explosion-Proof Seal-Off Compound Volume Calculator →Firestop Joint Movement and Sealant Volume Calculator →Shaftwall C-H Stud Limiting Height Calculator →Single-Sided Fire-Rated Gypsum Board Calculator →

Frequently asked questions

What is the difference between a firestop and a cavity barrier?
What they are closing. A FIRESTOP seals a hole made in a fire-resisting element — a pipe, a cable bundle, a duct passing through a compartment wall or floor — and its job is to restore that element's rating at the penetration. A CAVITY BARRIER closes or subdivides a concealed space: the gap behind a rainscreen, the void above a suspended ceiling, the space in a timber frame wall, the cavity in a masonry wall at a compartment line. The first is about a hole somebody made; the second is about a void the construction inherently has. They are different products, different tests and different clauses, and a building with perfect firestopping at every penetration and no cavity barriers has an unbroken route for fire through its own voids.
What do the F and T ratings mean, and why are there two?
Because a seal can stop flame passing while still letting enough heat through to start a fire on the other side. The F rating is the time the system resists the passage of FLAME and hot gases — the obvious requirement. The T rating is the time before the temperature on the unexposed side rises by a stated amount, which matters because a steel pipe passing through a wall conducts heat along itself and can ignite material touching it on the far side without any flame having passed. So a system can carry a two-hour F rating and a much shorter T rating, and which one a specification needs depends on whether anything combustible can be against the penetration on the unexposed side. A specification quoting only an F rating has not answered that.
Why is a tested SYSTEM specified rather than a product?
Because the rating belongs to the whole assembly, not to the sealant. A firestop test covers a specific combination: the element being penetrated and its construction, the service and its material and diameter, the annular gap, the depth and type of the seal, and the way it was installed. Change any of those — a copper pipe instead of steel, a larger gap, a thinner bead, a plasterboard wall of different construction — and the tested system no longer describes what was built, so the rating does not apply. That is why firestopping is documented by system reference rather than by product name, why photographs and labels at each penetration are standard practice on any building that will be inspected, and why filling a hole with a tube of something fire-rated is not firestopping.