Intumescent Coatings — Structural Steel Fire Protection
Nationwide

It is a reactive coating applied to structural steel that looks much like paint when dry. In a fire the heat causes it to swell to many times its original thickness, forming a thick insulating char that shields the steel underneath and slows the rate at which it heats up — keeping the frame below the temperature at which it loses strength for the required period.

Steel is strong but it weakens quickly as it heats. Around 550°C it retains roughly half its strength, and an unprotected frame can reach that in minutes, so the structure can fail long before the building has been evacuated. Building Regulations therefore require load-bearing elements to maintain stability for a set period — typically 30, 60 or 90 minutes — and intumescent coating is how exposed steel achieves it.

Off-site (shop-applied) coating is sprayed in controlled factory conditions before the steel is delivered, which gives consistent film thickness, faster erection and no wet trades on site. On-site application is used where steel is already erected, where a building is being refurbished, or to complete connections and make good after handling. We do both, and often a combination — off-site for the bulk of the frame, on-site for connections and touch-ups.

Typically R30 to R90 — 30, 60 or 90 minutes of load-bearing fire resistance — depending on the product, the section factor (Hp/A) of each steel member and the applied dry film thickness. The rating your steel needs is set by the building's fire strategy and Building Regulations, and we specify the thickness for each section from the manufacturer's tested loading tables.

Yes. We record the product used, the specified and achieved dry film thickness and the coverage for every element, with wet and dry film readings taken as we work. You receive that documentation on completion for building control, your fire safety file and any future fire risk assessment.