Intumescent Paint Specialists
Intumescent paint is a key asset for passive fire protection. By protecting the structural framework, intumescent paint extends the length of time a building can withstand high temperatures. This could make the difference between fully evacuating a building, and putting the lives of occupants and firefighters at risk.
CLM Fireproofing are experts in spray-applied fire protection. Our operatives have applied intumescent paint to some of London’s standout buildings, from The Shard to London City Airport. Our work ensures that these buildings are protected from fire, in full adherence to health and safety legislation. Visit our projects page to view more examples of our work.
How does intumescent paint work?
The word ‘intumescent’ is derived from the Latin word “tumesco”, meaning expand or swell. Intumescent paints or sealants undergo an endothermic process, meaning the materials within the paints expand when exposed to high temperatures. Intumescent coatings are applied to steel frameworks in buildings, offering enhanced fire protection without affecting the steel’s mechanical properties.
There are several ways to apply intumescent paint, the most common being spray-application as a film coating. Intumescent paint can be applied to steel, timber and an array of composite materials. Some varieties of intumescent paint can be given a decorative finish. In this instance, we would engage with the manufacturer to ensure that all the solutions we use are compatible with specific materials.
Under extreme conditions, steel will reach its ‘critical temperature’. The exact temperature can vary based on the building design. In Britain ‘critical temperature’ is commonly 550°, but has been known to range between 350° – 750°. Once this point is reached the steel will begin to lose its nominal integrity and load-bearing capacity.
Intumescent paint delays the point at which the steel reaches a critical temperature for a set period of time. If a steel framework is coated with intumescent paint, the paint will expand into a carbonaceous crust which solidifies once temperatures reach around 250°. This protects the steel for a certain length of time whilst the building is evacuated.
Intumescent coatings can be classified as either thin film or thick film. Thin film is the industry standard used in construction projects. In comparison, thick film coatings are mostly used to handle extreme temperatures in industrial environments.
How much does intumescent paint expand?
The rate of expansion for intumescent paint depends on its thickness. Thin-film coatings will expand at a rate of 50:1, as a general rule of thumb. This means that a 1mm coating will reach an estimated density of 50mm in the event of a fire. Thick film coatings expand at an approximate rate of 5:1. It is worth mentioning that if a project intends to apply intumescent paint, then several aspects of the building should be designed to accommodate the rate of expansion.