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Fire Barriers

We help ensure fire Barriers are installed to a high standard.

What is a cavity fire barrier?

In a home there are spaces called cavities. They are enclosed spaces that serve no real purpose, they are mostly found within walls between things like structural beams. These kinds of spaces within external walls can act as a chimney within a home, allowing flames and smoke to travel from one area of a building to another.

Unsealed cavities can allow air to be drawn in and smoke to vent out, enabling the fire spread to accelerate through the building. This is known as the ‘chimney effect’ and enables flames within a cavity to be able to extend between 5 and 10 times higher than a flame that is not within a cavity. This is regardless of whether or not the surfaces of the cavity are combustible.

A cavity barrier are blocks of fire-resistant materials that seal up these cavities in a wall to prevent the spread of fire and smoke. This is achieved by the fire-resistant material used to make the barrier expanding in the event of a fire and as a result sealing off the space. This helps with the compartmentation of a building during a fire. The performance of a cavity barrier must be at par throughout the building’s lifespan, taking into account any building movement through things such as shrinkage and subsidence.

What cavity fire barriers are not
Something similar to a cavity fire barrier is a cavity closer. These are also used to seal cavities within a building. However, unlike cavity barriers, cavity closers are not made with fire-resistant materials. They are used to prevent external water vapour and damp entering the cavity. They are NOT used for preventing the spread of fires.

That being said, if a cavity closer has been made using fire-resistant material, they could be considered a cavity barrier despite not being designed for that purpose.

Why are cavity barriers important?
Cavity barriers are important passive fire protection. They help to slow the fire down and are an essential part of protecting a building. They give anyone inside the building a greater amount of time to evacuate and can reduce the amount of damage to a property. Additionally, they help give firefights a greater chance of putting out the fire.
When should they be installed?
Cavity barriers are considered a mandatory fire protection. They should be installed by a building company during construction.

Older existing buildings may not have been built to this standard or may have been built before it was a legal requirement. As a result, their fire stopping provision should be regularly checked as part of their fire risk assessment.

Where should they be installed?
In accordance with building regulations, cavity barriers should be installed at the junction between an external cavity wall and every compartment floor and compartment wall. The exception to this is when the walls have two leaves or masonry or concrete with a minimum thickness of 75mm. Cavity barrier should also be installed at the junction between an internal wall and every compartment floor, compartment wall, or other wall or door assembly that forms a fire-resisting barrier.
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How should they be installed?
Every cavity barrier should be constructed and installed in such a way that it can provide the required level of fire protection. Wherever possible, a cavity barrier should be mechanically fixed tightly in place to a rigid construction.

Things such as building movements, the collapse or deformation of structures and surfaces, and the failure of the fixing should be considered when installing a cavity barrier. Opening and penetrations in cavity barriers should always be kept to a minimum in order to restrict the flow of smoke.

When cavity barriers are installed, it’s important to record all of their locations and the relevant maintenance information. This should all be put in the building’s fire safety manual. Building regulations require records of cavity barriers, including drawings of the positions and specifications in all compartment walls and doors. These can then be used to inform any future cavity barrier inspection and maintenance.

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