Fire Safety Glossary

A cavity barrier is a construction element installed within concealed voids — including ceiling spaces, roof voids, and wall cavities — to interrupt the paths along which fire and smoke can travel unseen and unimpeded. Cavity barriers form a critical part of a building's compartmentation strategy and must be present and undamaged, as identified during any fire risk assessment or compartmentation survey.

Compartmentation is the division of a building into fire-resisting cells using walls, floors, ceilings, and fire doors, designed to contain a fire within its compartment of origin for a specified period — typically 30 or 60 minutes. It is a core element of passive fire protection and is required in all non-domestic premises under Approved Document B and assessed through every fire risk assessment.

A fire damper is a passive fire protection device fitted within ductwork where it passes through a compartment wall or floor, designed to close automatically in a fire and prevent flames and hot gases from spreading through the ventilation system. Fire dampers must be installed, tested, and maintained in accordance with BS EN 1366-2, and their operation must be verified as part of every fire risk assessment.

A fire resistance rating is the tested period — typically 30, 60, 90, or 120 minutes — for which a building element maintains load-bearing capacity (R), fire integrity (E), and thermal insulation (I) when exposed to a standardised fire. Ratings are specified by Approved Document B and BS 9999 for walls, floors, doors, and structural columns depending on building type, height, and occupancy.

Fire stopping is the sealing of penetrations in fire-resisting walls, floors, and ceilings — such as gaps around pipes, cables, ducts, and conduits — using approved materials that restore the required fire resistance rating. Inadequate or missing fire stopping is one of the most frequently cited failures identified during fire risk assessments and compartmentation surveys.

Fire-resistant glazing is a glass or glazing assembly tested to provide fire resistance in doors, screens, partitions, and windows. It is rated for integrity (E) — resisting flame and hot gas passage — and optionally for insulation (EI) — also limiting heat transfer through the pane. It must be installed in certified assemblies, and its condition verified during fire door inspections and compartmentation surveys.

An intumescent seal is a strip or compound fitted around the edges of a fire door that expands rapidly when exposed to heat, sealing the gap between the door leaf and frame to prevent the passage of fire and hot gases. Intumescent seals are a mandatory component of all fire door assemblies and their condition is checked as part of every fire door inspection under BS 9999.

Passive fire protection (PFP) comprises the structural and material elements built into a building to contain or slow the spread of fire and smoke without requiring activation — including compartmentation, fire doors, fire stopping, cavity barriers, and structural fire protection. PFP elements must comply with Approved Document B and are assessed as part of a fire risk assessment.

Structural fire protection is the application of passive fire protection to load-bearing elements — including steel beams, columns, and concrete structures — to maintain their structural integrity for a specified period during a fire. Methods include intumescent coatings, spray-applied cementitious products, and fire-resistant board encasement, all specified to meet the fire resistance requirements of Approved Document B or BS EN 1993-1-2.