In the event of a fire, it's not just what you see that matters - it’s what happens in the hidden spaces you don’t. While active fire protection systems like alarms and sprinklers grab attention, cavity fire protection plays a quiet but critical role in slowing the spread of fire and smoke through the concealed voids within walls, floors and ceilings.
Cavity barriers and seals act as the unsung heroes of passive fire protection. These systems work behind the scenes to contain, compartmentalise and delay the spread of fire, helping to preserve structural integrity and, most importantly, save lives. Whether you're constructing a new build or retrofitting an older one, choosing the right cavity fire protection products is essential for regulatory compliance, long-term safety and peace of mind.
In this guide, we’ll explore the most effective solutions available, from intumescent sealants to fire-rated membranes and how they’re used to protect those often-overlooked, hard-to-reach spaces.
Envirograf Cavity Barriers and Strips
Envirograf Cavity Barriers and Strips are specially designed fire-stopping solutions that help prevent the rapid spread of fire and smoke through ventilated cavities in walls and roofs. These flexible yet robust products are crucial for maintaining compartmentalisation within a building, especially in voids that often go overlooked during standard fire protection planning.
Benefits:
- Expands on contact with fire, sealing cavities to contain flame and smoke
- Suitable for use in horizontal and vertical cavities
- Helps maintain fire compartmentation in walls and facades
- Compatible with a wide range of construction materials and build-ups
- Aids in achieving Part B Building Regulation compliance
- Available in various formats and custom sizes for different applications
- Ideal for timber frame, masonry and steel frame
Rockwool SCB
ROCKWOOL SCB (Stone Wool Cavity Barrier) is a robust and reliable passive fire protection product designed to maintain fire compartmentation in external wall cavities. Manufactured from non-combustible stone wool, this cavity barrier provides high levels of fire resistance, helping to slow the spread of fire and smoke through concealed spaces in both ventilated and unventilated cavities.
Benefits:
- Provides up to 120 minutes of fire integrity and insulation for enhanced safety
- Suitable for use in both timber and masonry cavities
- Supports compliance with fire safety regulations and building standards
- Easy to handle and install, with flexible sizing for a variety of applications
- Made from durable, water-repellent, and rot-resistant stone wool
- Environmentally sustainable solution with long-term performance benefits
- Can be easily cut to size
PFC COROFIL Acoustic Intumescent Sealant
When exposed to high temperatures, the sealant resists fire (intumesces) to form a fire-resistant barrier, helping to contain fire and smoke at its point of origin. In addition to its fire-stopping capabilities, it also reduces sound transmission, supporting both fire safety and acoustic performance in a single application.
Benefits:
- Flexible, cost-effective and very easy to apply with a standard mastic gun
- Provides up to 4 hours of fire resistance (subject to installation and configuration)
- Excellent acoustic insulation, reducing unwanted noise between rooms
- Suitable for horizontal and vertical joints
- Ideal for sealing around metal pipes, conduits and cable trays
- Supports building regulation compliance for both fire and acoustic performance
Rockwool Ablative Coated Batt
When installed correctly, ROCKWOOL Ablative Coated Batt provides an effective firestopping solution designed to maintain the fire resistance of walls and floors where services penetrate. The mineral wool core is coated with a fire-resistant ablative sealant, which prevents the spread of fire and smoke while also offering excellent acoustic insulation. This makes it ideal for sealing service penetrations and providing reliable compartmentation in commercial, residential and industrial buildings.
Benefits:
- Provides up to 4 hours of fire resistance (dependent on application and installation)
- Stops the spread of fire and smoke at service penetrations
- Excellent acoustic performance, reducing sound transmission between rooms and floors
- Easy to install and cut to size, ensuring a neat fit around services
- Versatile solution suitable for walls and floors, including around pipes, ducts, and cable trays
- Helps achieve compliance with building regulations for both fire and acoustic requirements
- Durable and long-lasting, maintaining performance over time
Tenmat CavGuard Roll 65
Tenmat CavGuard Roll 65 is a high-performance cavity fire barrier specifically designed to firestop cavities behind external walls with masonry or brickwork substrates. Crafted from a low-smoke zero-halogen (LSZH) intumescent material, this barrier remains highly expansive during a fire, effectively sealing the cavity to prevent the spread of flames and smoke, while allowing ventilation in normal conditions.
Benefits:
- Provides up to 60 minutes of fire resistance within external wall cavities
- CCPI Verified for reliable fire safety performance
- Ventilated design maintains airflow in uninsulated cavities, reducing the need for cavity trays or weepholes
DuPont™ Tyvek® Trifecta™ A2 Fire-Rated External Breather Membrane
Tyvek® Trifecta™ stands out by not producing droplets or emitting smoke when exposed to flames, significantly reducing fire risk in sensitive build-ups. Its non-combustible nature ensures it acts as a reliable fire barrier within cavity walls and roofs, helping to slow the spread of fire and smoke.
Benefits:
- Euroclass A2 (s1, d0) non-combustible rating for superior fire safety compliance
- Does not produce smoke or flaming droplets under fire conditions, enhancing safety
- Vapour-open membrane supports breathability and moisture control
- Airtight and watertight for improved energy efficiency and indoor comfort
- Fast and easy installation, paired with non-combustible A2 tape for secure sealing
- Robust, durable membrane suitable for high-risk, high-rise construction
Dacatie TFR2000 Fire-Rated Cavity Closer Barrier
Dacatie Cavity Closers are manufactured from A1-rated mineral wool slab. They are the perfect solution for builders and specifiers looking to effectively close cavity spaces around window and door openings. Designed to create a continuous insulated barrier that prevents cold bridging, damp penetration, air leakage and condensation around openings. It also contributes to improved fire safety by reducing gaps where fire and smoke could spread within cavity walls.
Benefits:
- Complies with Part L Building Regulations for thermal performance
- Rigid PVCu frame with CFC-free insulation core for superior durability and insulation
- Suitable for all cavity widths from 100 to 160mm, adaptable to various builds
- Compatible with timber, PVCu, and aluminium window and door frames
- Can be installed during the first or second fix for flexible application
- Ideal for closing reveals and cavity spaces in new builds and retrofit projects
- Enhances overall building airtightness and energy efficiency
OBEX Cortex (0221FR) Fire-Rated Breather Membrane
OBEX Cortex (0221FR) Fire-Rated Breather Membrane is a high-performance, fire-rated membrane designed for use on the external side of buildings to enhance fire safety while allowing moisture to escape. Ideal for high-rise and high-risk buildings, this breather membrane offers excellent weather protection and vapour permeability without compromising fire performance.
Benefits:
- Euroclass B-s1,d0 fire rating for enhanced fire protection in facade systems
- Highly breathable to allow vapour to escape and reduce condensation risks
- Durable and UV-resistant for long-term external exposure
- Suitable for both residential and commercial projects, including high-rise buildings
- Easy to install with strong mechanical strength and tear resistance
- Supports compliance with building fire safety regulations and performance standards
SIGA Trestard® 420 black FR (Fire-Rated Tape)
SIGA Trestard® 420 Black FR (Fire-Rated Tape) is a flame-retardant adhesive tape designed to provide a secure and durable seal for overlaps, joints, and penetrations in fire-rated building envelope systems. Engineered for safety and performance, this tape is ideal for projects requiring airtightness and enhanced fire resistance.
Benefits:
- Flame-retardant for added fire protection in critical building applications
- Strong adhesion on a wide range of surfaces, including membranes and boards
- Supports airtight construction by sealing joints, overlaps and detail work
- UV-stable and weather-resistant for lasting exterior performance
- Flexible and easy to apply, even around complex shapes and corners
- Ideal for use in both new build and retrofit fire protection systems
Why It Matters
When properly installed, cavity fire protection measures can:
- Prevents the spread of fire by segregating void spaces within ceilings, walls and floors
- Without proper measures in place, a fire can spread up to 10 times faster
- Allows more time for evacuation and fire response
- Protects escape routes
- Improves fire compartmentation
- Support regulatory compliance
- Maintains building integrity
And with modern, tested products from leading names like Envirograf, Tenmat and Tyvek, you can integrate fire protection without compromising on thermal efficiency or build quality.
Final Thoughts
Whether you’re building a high-rise, retrofitting a period property or just aiming to meet the latest safety standards, cavity fire protection should never be an afterthought.
It is always important to consult your architect, engineer or building standards officer prior to installing any products to ensure they are correct for application.
Need help choosing the right solution?
Contact our team at sales@ultimate-insulation.co.uk or give us a call on 01786 447997.
