Description
Thermoguard Intumescent Mastic
Thermoguard Intumescent Mastic is a one-part acrylic fire-rated sealant designed to seal joints, gaps, voids and service penetrations within fire-rated walls, floors and partitions.
When exposed to extreme heat, the mastic expands to form an insulating char barrier that helps prevent the passage of fire, smoke and hot gases through openings in fire compartmentation systems.
Designed for both fire stopping and acoustic sealing applications, the product remains flexible after curing and is suitable for a wide range of construction environments.
What It Does
- Seals joints, voids and irregular gaps in fire-rated structures.
- Expands during fire conditions to help block fire and smoke spread.
- Maintains fire compartmentation around penetrations and openings.
- Provides flexible acoustic and air sealing benefits.
- Suitable for use around cables, pipes and service penetrations.
Why Choose Thermoguard Intumescent Mastic?
- Fire stopping performance: helps maintain the integrity of fire-rated walls and floors.
- Flexible after curing: designed to accommodate normal building movement.
- Easy application: suitable for gun or trowel application.
- Wide substrate compatibility: adheres well to many common construction materials.
- Acoustic sealing benefits: helps reduce sound transmission through joints and openings.
Where It Can Be Used
- Fire-rated plasterboard partitions
- Concrete and masonry walls
- Concrete floor slabs
- Fire door frame joints
- Window frame gaps
- Cable trays and cable bunch penetrations
- Metallic pipe penetrations
Ideal For
- Commercial construction projects
- Schools and hospitals
- Office developments
- Apartment and residential blocks
- Plant rooms and service risers
- Fire stopping upgrades
- Refurbishment and compliance works
Fire Performance
- Tested to EN 1366-3 for penetration seals.
- Tested to EN 1366-4 for linear joint seals.
- Fire resistance ratings up to EI 240 in suitable systems.
- BS476 fire resistance testing up to 300 minutes.
- Fire classification to EN 13501-2.
How It Works
- Under heat exposure, the acrylic mastic expands and chars.
- The expanding char seals openings against fire and smoke passage.
- This helps preserve the integrity of compartment walls and floors.
- The system can also help maintain acoustic insulation performance.
Suitable Substrates
- Concrete
- Masonry
- Blockwork
- Plasterboard partitions
- Rigid walls and floors
- Flexible wall systems
Application Information
- Apply using a standard mastic gun or trowel.
- Joints and openings should be clean and free from dust and grease.
- Backing materials may be required depending on joint depth and specification.
- Can be painted after curing where required.
- Always follow Thermoguard installation guidance and tested detail specifications.
Performance Benefits
- Remains flexible after installation.
- Good adhesion to many common building substrates without priming.
- Halogen free formulation.
- Resistant to fungi and vermin.
- Provides acoustic isolation benefits within suitable constructions.
Service Penetrations
- Suitable around metallic pipes and conduits.
- Suitable around cable trays and cable ladders.
- Can be used around cable bunches and mixed service penetrations.
- Designed to reinstate fire resistance around penetrations through walls and floors.
Good To Know
- Correct joint dimensions and installation depth are essential for certified fire performance.
- Fire ratings vary depending on substrate type and opening configuration.
- Always refer to tested details before installation.
- Suitable for both fire stopping and acoustic sealing applications.
- Project-specific specification advice is recommended for regulated environments.
Need To Seal Fire-Rated Joints Without Complex Installation?
Thermoguard Intumescent Mastic provides a practical fire stopping solution for joints, penetrations and voids within fire-rated structures. Its flexible acrylic formulation makes installation simpler while still delivering professional fire resistance performance.
Need Help Specifying Fire Stopping Details?
Different wall types, penetration sizes and joint widths require different fire stopping configurations. If you are unsure which detail or fire rating applies to your project, contact the Thermoguard technical team before installation.
Technical Support: 01142 768008
Email: technical@thermoguard.co.uk
