In modern construction, fire safety is paramount
One of the most crucial elements of fire protection within construction is the use of cavity barriers. These barriers play a vital role in containing fire and smoke, limiting their spread through hidden cavities in walls, floors, and ceilings.
This guide will cover everything you need to know about cavity barriers, including ventilated or open state cavity barriers, from basic definitions to legal regulations, real-world applications, and their importance in ensuring building safety.
Find out more about Cavity Barriers in the following sections:
What are Cavity Barriers?
Cavity barriers are fire-resistant products installed within the hidden cavities of a building’s structure. These barriers limit fire and smoke from travelling through cavities, which are often found in walls, floors, and ceilings. Without these barriers, fire can spread rapidly through a building’s unseen spaces, endangering both the structure and its occupants.
Cavity Barrier Key Features
Locations
Installed in concealed spaces such as wall cavities and external façades, floors, ceilings, and roof voids.
Materials
Common materials include stone wool, fire-resistant boards, intumescent materials, and other non-combustible components.
Performance
They are designed to withstand high temperatures, ensuring that fire does not pass through.
Types of Cavity Barriers
Stone Wool: Known for its excellent fire resistance and insulation properties, it is a go-to material for cavity barriers.
Fire-Resistant Boards: Durable and ideal for fire protecting larger cavity spaces.
Flexible Fire Barriers: Fire resistant and lightweight fabric fire barriers most suited to large cavity spaces
Expanding Intumescent Strips: These barriers maintain open air gaps for ventilation and then expand when exposed to heat, sealing the gaps that could allow fire or smoke to pass through.
Ventilated or Open State Cavity Barriers
What Are Ventilated or Open State Cavity Barriers?
Ventilated or open state cavity barriers are specifically designed for use in ventilated external wall systems. These barriers not only prevent fire spread but also allow for airflow in normal use, which is crucial for preventing moisture buildup and ensuring the long-term health of building façades.
Applications of Open State Cavity Barriers
Ventilated Facades: Used in external walls of residential and commercial buildings where ventilation is needed for moisture control.
High-Rise Buildings: Common in modern high-rise buildings, ensuring fire safety without compromising air circulation.
Non-Combustible Materials: Tenmat’s open state cavity barriers combine non-combustible stone wool with intumescent materials, offering excellent fire resistance.
Cavity Barrier Key Features
Dual Functionality
Fire containment and ventilation in one solution.
Enhanced Building Health
Prevents fire spread while allowing natural airflow, reducing moisture risk.
Fire Tested
Proven performance following test standards and methodology like BS EN 1363-1, BS EN 1346 and TGD19.
Importance of Cavity Barriers in construction and fire safety
Cavity barriers are an essential component of passive fire protection systems. While active systems like sprinklers and alarms work to extinguish or alert people to a fire, cavity barriers function by containing the fire at its point of origin. This containment is crucial for maintaining the structural integrity of a building and for ensuring the safety of its occupants.
Read more on why fire tested solutions are more important than ever in construction safety.
Cavity Barrier Key Features
Fire Containment
They help limit the spread of fire and smoke particularly in hidden or difficult to access areas of the building.
Evacuation
By restricting fire spread, cavity barriers provide more time for building occupants to evacuate safely.
Smoke Containment
Smoke inhalation is one of the leading causes of fatalities in fires. By limiting smoke spread, cavity barriers contribute to a safer evacuation environment.
Fire Fighting
They delay the spread of fire in building cavities giving the fire services valuable time to tackle the fire.
Supporting Fire Safety Regulations
Cavity barriers ensure that buildings meet fire safety regulations and standards.
Non-compliance can result in not only legal ramifications but also increased risk to lives and property in the event of a fire. Building codes mandate the use of cavity barriers, particularly in structures with multiple floors or complex layouts where fire could spread quickly.
How Cavity Barriers prevent fire and smoke spread
Cavity barriers are specifically designed to block the pathways that fire and smoke would otherwise use to spread.
Cavities, which are often out of sight, are present in most modern buildings; they can include cavity walls and other voids found in floors, roofs, and ceilings.. Without proper barriers, these cavities can act like open paths or chimneys, allowing fire and smoke to travel quickly from one part of a building to another.
The mechanics of fire containment
Fire compartmentation inhibits the spread of fire, smoke and heat from one area to another. This ensures that any fire is contained within a specific section of a building for longer, meaning building occupants have more time to safely evacuate and that firefighters have greater control over the fire.
Cavity barriers work by sealing off these gaps, ensuring that fire and smoke are confined to one area. This not only limits the spread of fire but also prevents smoke, which can be just as deadly, from spreading throughout the building. Effective fire containment through cavity barriers provides critical time for occupants to evacuate and for emergency responders to control the situation.
Part of a passive fire protection system
Cavity barriers are one element of a broader passive fire protection strategy, which also includes fire-resistant walls, floors, and doors, and penetration systems.
Together, these systems work to contain fires and minimise damage, offering a comprehensive approach to fire safety. Unlike active fire protection systems, which require activation (such as sprinklers), passive systems like cavity barriers function continuously and do not rely on human intervention or electronic triggers.
Read more on the importance of early engagement in fire protection installations.
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Overview of legal regulations and standards for Cavity Barriers
Fire safety regulations in the UK are stringent, and cavity barriers must meet specific standards to ensure they perform as required during a fire emergency. Compliance with these regulations is essential for the safety of occupants and for meeting legal obligations.
Key UK fire safety regulations
- Building Regulations Approved Document B: This is one of the most critical documents for fire safety in the UK. It outlines the fire safety guidance for residential and commercial buildings, ensuring that cavity barriers are correctly installed in areas like wall cavities, roof voids, and floors.
- BS 9991: This standard specifies fire safety requirements for the design, management, and use of residential buildings, including guidelines for installing cavity barriers.
- BS 9999: Focused on non-residential buildings, BS 9999 offers guidance on fire safety strategies, including the installation and maintenance of cavity barriers.
- Fire Resistance Ratings: Cavity barriers must meet certain fire resistance ratings to ensure they can contain fire for a specified fire resistance duration (e.g. 30 minutes integrity and 15 minutes insulation), depending on the building’s design and usage.
Cavity Barrier Key Features
Certified Materials
It’s critical to use cavity barriers that are 3rd party tested and where possible 3rd party certified for fire resistance. Materials must meet the fire ratings specified in regulations to be effective during a fire.
Application Appropriate
It is essential that cavity barriers have been tested in representative construction types to ensure that cavity barriers are capable of performing their function when installed within a range of substrate types.
Liability and Safety Risks
Non-compliance can lead to serious legal consequences, including fines, and more importantly, it increases the risk of injury or death in the event of a fire.
Applications of Cavity Barriers in residential and commercial buildings
Cavity barriers are used in a wide range of building types, from residential homes to large commercial spaces. Each application comes with its own set of challenges, but the underlying need for fire safety remains constant.
Residential applications
Cavity barriers are essential for homes, apartments, and multi-occupancy dwellings. Cavities can include gaps in cavity walls, and other voids found in floors, roofs, and ceilings where fire could spread. Barriers in these spaces prevent fire and smoke from moving between rooms or floors, containing the damage and providing valuable time for evacuation.
- Common uses in residential buildings
- Party Floors: Cavity barriers are installed at the junction of party floors to limit fire spread in the cavity from one floor to another, e.g. within outer brickwork or façade cavities.
- Around windows/openings: Cavity barriers are designed to restrict fire spread through cavities created around openings in external walls such as those formed for windows.
- Party Walls: Cavity barriers are installed in the cavities of party walls to prevent fire from spreading between adjoining properties.
- Lofts and Roof Voids: Fire can spread quickly through roof spaces, so cavity barriers in these areas are vital for containing flames.
Commercial applications
In commercial buildings such as office blocks, retail spaces, and warehouses, cavity barriers must be designed to accommodate the specific fire safety needs of each structure. These buildings often have large open spaces, making the correct placement of cavity barriers even more important.
- Common uses in commercial buildings
- Office Partitions: Cavity barriers are installed between office partitions to limit the spread of fire through large, open-plan spaces.
- Raised Access Floors: Cavity barriers are often used to limit fire spread in raised access floors, which are floor voids used to pass services through.
- External Walls: Cavities in external walls formed either behind outer brickwork or ventilated façades would require cavity barriers to prevent hidden fire spread.
Final thoughts
Cavity barriers, including ventilated or open state cavity barriers, are crucial for modern fire safety, protecting both residential and commercial buildings from the devastating effects of fire. By preventing the spread of fire and smoke, these barriers save lives, protect property, and help to ensure the structural integrity of a building during an emergency.
As fire safety regulations continue to evolve, it’s essential for builders, developers, and property managers to ensure cavity barriers are installed correctly and comply with all relevant standards. Proper planning, design and installation are key to ensuring these barriers provide the protection they are designed to deliver.
FAQs
Cavity barriers are fire-resistant products installed in the cavities of walls, floors, and ceilings to prevent the spread of fire and smoke. They are essential for maintaining fire safety in both residential and commercial buildings.
Cavity barriers must comply with UK fire safety regulations, including Building Regulations Approved Document B, BS 9991, and BS 9999, which dictate fire safety requirements for buildings.
Cavity barriers prevent fire and smoke from travelling through hidden cavities, effectively containing the fire within a compartment and limiting its spread.
They are used in a wide range of buildings, including residential homes, apartments, offices, warehouses, and retail spaces.
3rd party tested and certified cavity barriers ensure that the materials used meet legal fire safety standards, providing effective protection in the event of a fire and ensuring compliance with building regulations.
