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:
- Primer.
- 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.
Standardised fire tests must be carried out to certify intumescent coatings for steel construction. Technical standards such as BSI, ASTM and ISO provide details for individual building parts.
[edit] Related articles on Designing Buildings
- Cavity barrier.
- Cementitious fire protection.
- Concrete vs. steel.
- Finishes.
- 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).
- Passive fire protection is a vital tool in any fire strategy.
- Substrate.
Featured articles and news
ECA Industry Awards 2024 shortlist revealed
22 leading businesses from across the electrotechnical and engineering services sector.
Government unveils Skills England strategy
Skills England to transform opportunities and drive growth.
New Government Hub for York Given Planning Green Light
For up to 2,600 civil servants, due for completion by 2028.
Construction Skills Certification Scheme cards
July update on Professionally Qualified and Academically Qualified Person Cards.
BSRIA Briefing 2024, November 22
Sustainable Futures: Redefining Retrofit for Net Zero Living.
The CLC on driving competency in the retrofit sector
Previously published roadmap on skills for net zero.
The first labour government King's speech in fifteen years
Construction industry reactions, support and some concern.
CIOB Retrofit of Buildings Technical Information Sheet
What retrofit is, the approach to be taken and processes to be followed.
Adapting Historic Buildings for Energy and Carbon Efficiency
Historic England advice note 18, free download published.
10 retrofit projects revisited 10 years after completion.
Information orders, building liability orders and SPVs
Key BSA terms and how they impact special purpose vehicles.
Listed despite problems with its design.
Zen and the art of cycling exploration.
Design Council Homes Taskforce launched
To support government 1.5 million homes target within UK climate commitments.