Open-State Cavity Barriers
for Ventilated Façades
Close the hidden paths fire travels behind cladding.
Ventilated facades and concealed cavities let fire and smoke spread unseen. Cavity barriers close those paths in a fire while allowing the ventilation the facade needs in normal use. Toggle the section to see both states.
Ventilated (service state): the Cavity Fire barrier is fixed to the structure with its intumescent seal facing the cladding, leaving a designed air gap (up to 44 mm) so the cavity stays ventilated and drained.
Open-state cavity barriers are tested to BS 8414 (principles of ASFP TGD 19). The free-air-gap must match the tested configuration, not the nominal cavity width. Pairs with vertical non-ventilated barriers along compartment party-wall lines.
Cavity barrier, façade fire barrier, cavity fire stop — what specifiers mean
On Indian façade projects these terms get used for one another, so it pays to be precise on the BOQ. An open-state cavity barrier closes a ventilated rainscreen cavity: it stays open to airflow in normal service and seals in fire. A ventilated façade fire barrier is the same product named by where it sits, and a façade cavity fire stop is the field name for that seal once installed.
These are distinct from a perimeter or façade barrier that seals the gap between the floor-slab edge and the external wall, and from firestopping, which reinstates a rated wall or floor where a service penetrates it. Different junctions, different tested systems.
Getting the vocabulary right matters because the certificate covers a tested configuration — cavity width, residual air gap, orientation — not the nominal opening on the drawing. Specify the open-state barrier against the gap it was actually tested at.
Specifying open-state cavity barriers for a ventilated façade? Send the cavity width, rating and cladding build-up and we will match it to a tested configuration.
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