- Project plans
- Project activities
- Legislation and standards
- Industry context
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
Survey reveals green skills gap.
America's economic collapse produced scores of PWA Moderne projects.
The benefits of glowing aggregates and cement.
Urgent need for open communication to address mental health issues.
Guidance offered on COVID-19 green recovery, building safety and more.
Providing strength and support above the joists.
Enforcer will test and investigate product safety.
Underfloor air conditioning comes to 24 St James's Square.
Consultation on public right to buy unused public property.
IHBC resource offers improved consistency.
New laws to ‘retain and explain’ historic statues.
The principles and art of the possible. Book review.