Intumescent Paint for Fire Protection
Intumescent paint is a fire-resistant coating used to protect structural steel and other load-bearing elements from rapid temperature rise during a fire.
Under UK Building Regulations, structural elements must maintain stability for a specified fire resistance period — typically 30, 60, 90 or 120 minutes. Intumescent coatings are one of the most effective and widely specified methods of achieving this requirement.
How Intumescent Paint Works
Steel begins to lose significant structural strength at approximately 550°C. In an unprotected condition, this temperature can be reached within minutes during a developed fire.
When exposed to heat, intumescent paint undergoes a controlled chemical reaction:
- Activation: Heat triggers expansion.
- Intumescence: The coating expands many times its original thickness.
- Char Formation: A carbon-rich insulating layer forms.
- Thermal Insulation: Heat transfer to the steel is slowed, delaying structural failure.
The thickness of the applied coating is calculated based on:
- Section factor of the steel (Hp/A)
- Required fire resistance period
- Critical steel temperature
Correct specification and film thickness control are essential to achieving compliance.
Where Intumescent Coatings Are Used
Intumescent paint is commonly applied to:
- Structural steel beams and columns
- Mezzanine floors
- Car park structures
- Timber elements (where tested systems apply)
In commercial and multi-occupancy buildings, intumescent coatings are often preferred over board systems where architectural finish and exposed steelwork are required.
Compliance and Certification
Application must follow manufacturer-tested systems and be installed to the specified dry film thickness (DFT). Improper application can result in non-compliance and reduced fire resistance performance.
Professional installation includes:
- Surface preparation and primer compatibility checks
- Controlled spray or brush application
- Wet and dry film thickness measurement
- Inspection and documentation
All works should align with UK Building Regulations and recognised third-party certification schemes.
Maintenance and Ongoing Performance
Intumescent coatings must remain intact to perform correctly. Damage, impact or unapproved overcoating can compromise protection.
Periodic inspection is recommended, particularly in areas subject to mechanical wear or environmental exposure.
Professional Intumescent Paint Application
LPP Fire Protection provides certified application of intumescent coatings across commercial and residential projects. Our team ensures correct specification, measured application and documented compliance.
We operate to recognised industry standards and are accredited by
BM TRADA.
To discuss structural fire protection requirements, contact our team for technical guidance and project support.
