- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 08 Nov 2020
Intumescent coatings in buildings
An intumescent is a substance that, when exposed to heat, increases in volume and decrease in density. Intumescent coatings are commonly used in passive fire protection. They are typically water-based, solvent-based or epoxy-based paint-like materials that expand when heated to form a ‘char’ which protects steel in the event of fire. This is important as steel softens at high temperatures, which can cause structural collapse. Steel can also be protected from fire by being encased in masonry, concrete or plasterboard,
Intumescent coatings can be categorised as either thin film or thick film.
Thin film coating systems tend to be either solvent- or water-based and can be used for fire protection in buildings with resistance requirements of 30, 60 and 90 minutes. They usually consist of three layers:
- Basecoat (the reactive component).
- Sealer coat.
The typical expansion ratio of a thin film is 50:1, meaning that a coating 1 mm thick will expand to approximately 50 mm when in contact with fire. The advantages of thin film are that both solvent and water-based coatings can achieve decorative and bespoke surface finishes, and can easily cover complex shapes.
Thick film coatings systems tend to be epoxy-based and have been modified for use in buildings having originally been developed for offshore and hydrocarbon industry applications where the test heating process is more stringent than that for industrial and commercial applications. The typical expansion ratio is much lower than thin film, usually 5:1.
 Related articles on Designing Buildings Wiki
- Cavity barrier.
- Concrete vs. steel.
- Fire protection engineering.
- Fire resistance.
- Fire retardant.
- Fire safety design.
- Installing fire protection to structural steelwork (GG 85).
- Intumescent strip.
- Metal fabrication.
- Paints and coatings.
- Passive and reactive fire protection to structural steel (IP 6 12).
Featured articles and news
LETI publishes guidance for energy efficient home retrofits.
Predictions about adequate post-pandemic IAQ in non-domestic buildings.
Government publishes plans to 'build back greener'.
The contentious nature of claims associated with cladding, fire safety and EWS1 forms.
ECA comments on low-carbon heating systems initiative and Heat and Buildings Strategy.
Cinders and other forms of domestic rubbish created filth but also generated great wealth.
CIC 2050 Group requests input to find out priorities for future industry leaders.
IHBC publishes response to consultation.
Institute applauds funding initiatives but presses for additional retrofit and tax measures.