What cavity barriers do
A cavity barrier seals a concealed space so that fire and smoke cannot travel through it, maintaining the compartment line where it passes through voids rather than rooms. Like all passive fire protection, barriers are tested products with tested limits: a barrier installed in a wider cavity, a different orientation or with different fixings than it was tested with is not a barrier — it is insulation in the wrong place.
Where barriers are needed
Ceiling and roof voids
Above suspended ceilings and through roof spaces, barriers must continue every compartment wall line up to the slab or roof above. In surveyed buildings, this is the most commonly missing link.
Junctions and slab edges
Floor-to-wall junctions and slab-edge details, where changes in construction create gaps that flame and smoke exploit — sealed with systems tested for the movement and geometry of the junction.
Risers and shafts
Vertical service routes act as chimneys between floors. Barriers and void closures restore floor-line separation while accommodating the services that must pass through.
External wall cavities
Within external wall build-ups, barriers restrict fire spread inside the cavity at compartment lines and around openings — a detail whose importance has needed no explanation since 2017.
How void protection fails
Removed and never replaced
Refurbishments and service installations displace barriers that are never reinstated — and above a ceiling grid, nobody notices for years.
Installed outside tested scope
A barrier tested at one cavity width does not perform at a wider one. Oversized cavities need the correct product for the span — not the same product stretched.
Poor fixing and compression
Barriers rely on correct fixing and compression to resist the pressure of a fire. Draped, unsupported or gapped installations fail early and invisibly.
No continuity
A barrier line with one gap in it is not nearly-effective — smoke finds the gap. Continuity has to be verified barrier by barrier, junction by junction.
What you receive
As-installed photographic records referenced to the compartmentation drawings, with product certification and tested-scope evidence for every barrier fitted — proof that the concealed lines of defence actually exist, and will still be provable the next time the void is opened.
Specified and installed by one team
Goldthread specifies each barrier to the actual cavity — its width, orientation and construction — and installs to the tested detail, recording everything before the void is closed. No generic product schedules, and no assumptions about what the void 'probably' is.
The parts of the building nobody sees deserve the most scrutiny.
Ask us to look above the ceiling line.
Contact us