Why specify a fire-rated cavity closer?

Cavity walls provide a continuous hidden path around the building, potentially spreading fire from one part of the structure to another without being detected.

Walls often form, or shroud, the critical structure of building. A fire established within this structure could lead to severe damage to the structural integrity of the whole building, leading to collapse.

Cavity barriers prevent the spread of fire by interrupting the cavity with a fire resistant material. Part B of the Building Regulations (for both residential construction and nondwellings) requires the use of cavity fire barriers around openings in all timber or steel frame cavity walls and in masonry walls where a particular risk has been identified by the building inspector. A cavity fire barrier must span the cavity and be securely fixed. It must also pass a fire test proving its capability to maintain integrity in an intense fire and restrict heat being conducted from the fire to other parts of the structure.

Why choose a cavity closer?
• Provides a damp proof course around the opening
• Simplifies brickwork – no brick returns needed
• Provides thermal break:
- Stops cold bridging which can cause condensation to form inside an opening damaging internal decoration and plaster work - Improves heat loss at the window junction, reducing CO2 emissions - Meets Accredited Construction Details regulation designed to improve the heat loss at junctions

Why choose a former?
• Provides a template for brickwork to follow ensuring sizes are correct and saving on dummy carpentry
• Ensures the window manufacturer can produce to correct sizes without repeated surveying - saving time and money by reducing re-work or snagging

The Cavalok FlameBlok solution

Combining a cavity fire barrier and cavity closer former in one product.

Features and benefits:
• Cavity barrier to Part B, Table A1 of building regulations
• Reduces fire risk during construction
• Superior thermal performance to other traditional methods of closing cavities, such as battens in timber frame or returned brickwork
• Saves labour on site – just one product closes the cavity and fire protects
Only with FlameBlok:
• FlameBlok creates a continuous fire-rated ring around the opening
• Rigorously tested for all cavity sizes and construction types
• Manufactured from 100% postconsumer recycled PVC-U for minimum environmental impact
• Simple, robust design like all Cavalok products
• Unique custom foil wrapped product makes mineral wool product easier to handle and reduces spread of flame
• Compatible with existing Cavalok components to keep Cavalok principle of a ‘no fuss’ product system
The testing:
• Full and rigorous testing carried out by Chiltern International
• Cavity sizes up to 150mm tested
• 60 minute integrity and 45 minute insulation in all constructions
• 90 minute integrity and 90 minute insulation in masonry
• Check reveal and flush reveal construction details tested
• Tested to BS EN 1363 as demanded by building regulations
• Minimal, ‘worst case’ construction tested to give confidence that the product performs in reality
• In testing timber frame failure occurs before product failure
• Simulates flashover point of fire with 1000˚C temperatures sustained for an hour or more