The Problem with Unprotected Steel
Steel is one of the most popular construction materials due to its strength, versatility, and cost-effectiveness. However, it has one significant weakness: it loses structural integrity when exposed to high temperatures. At around 550°C, steel retains only about 60% of its strength, and at 700°C, it can begin to fail catastrophically.
In a fire, temperatures can exceed 1000°C within minutes. Without protection, steel structural elements can deform or collapse, potentially bringing down an entire building. This is where intumescent coatings provide a vital safeguard.
What Are Intumescent Coatings?
Intumescent coatings are specially formulated paints that react to heat by expanding dramatically – up to 50 times their original thickness. When exposed to fire, the coating transforms into a thick, insulating char layer that protects the underlying steel from reaching critical temperatures.
How Intumescent Coatings Work:
Heat exposure triggers a chemical reaction in the coating
The coating expands rapidly, forming a thick foam-like char
The char insulates the steel, keeping it below critical temperature
Types of Intumescent Coatings
Thin Film Intumescent
Applied at 0.2mm to 5mm thickness. Looks like regular paint when dry. Expands to form a thick char when heated.
Best for: Interior steelwork, architectural applications
Thick Film Intumescent
Applied at 3mm to 25mm thickness. More durable and weather-resistant. Suitable for harsh environments.
Best for: External steelwork, industrial settings
Fire Ratings Explained
Intumescent coatings are tested and certified to provide specific fire resistance periods, typically:
30
minutes
60
minutes
90
minutes
120
minutes
The required fire rating depends on the building type, size, occupancy, and regulatory requirements. Building Regulations Approved Document B specifies minimum fire resistance periods for different building categories.
Benefits of Intumescent Coatings
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Aesthetic Appeal: Thin film coatings preserve the aesthetic appearance of architectural steelwork.
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Space Efficiency: Unlike board systems, coatings don't add significant bulk to steel sections.
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Versatility: Can be applied to complex steel profiles that would be difficult to protect with boards.
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Colour Options: Available in various colours or can be overcoated with decorative topcoats.
Professional Application Required
Intumescent coatings must be applied by trained professionals to ensure correct thickness, adhesion, and coverage. All work should be documented and certified for building regulation compliance.
Our Intumescent Coating Services
At Passive Fire And Access, we combine our expertise in intumescent coatings with rope access capabilities, enabling us to protect steel structures at any height without costly scaffolding. Our services include surface preparation, primer application, intumescent coating, topcoat finishing, and full documentation for compliance.