Intumescent Paint Contractors

Intumescent fireproofing is often key for reinforcing steel structures within a passive fire protection strategy. By adding a protective layer to structural steel, intumescent paint extends the length of time a building can withstand high temperatures. This not only reduces damage to steel, but it could also make the difference between fully evacuating a building and putting the lives of occupants and firefighters at risk.

CLM Fireproofing specialises in the application of intumescent coatings for steel structures in construction projects. With our in-depth technical knowledge, we can swiftly and effectively reinforce structural elements and surfaces, without compromising on their basic functionalities or aesthetic finishes. Our team is also able to apply intumescent coatings both onsite and offsite. This allows us to enact the strictest possible standards of quality control, so clients can be certain that their projects comply fully with building regulations.

As the UK’s leading specialists in passive fire protection, fire stopping and fire doors, our highly skilled operatives have worked on some of London’s standout commercial buildings, from The Shard to Battersea Power Station. Our guidance and technical advice gives clients peace of mind that their projects are fully protected from structural fire damage. Consult our range of case studies to view our comprehensive range of fire protection projects.

Our presence in the industry also means we’ve built up an extensive network of quality vendors and third-party technicians. As accredited members of the Association for Specialist Fire Protection (ASFP), we are committed to sharing knowledge and can be relied on to recommend a product for any specific need.

How does intumescent fireproofing work?

When subjected to extreme heat exposure, steel will reach its ‘critical temperature’. The exact temperature can vary based on the building design. In Britain, it is commonly 550° but has been known to range between 350° – 750°. Upon reaching its critical temperature steel will begin to lose its nominal integrity and load-bearing capacity, increasing the likelihood of structural collapse.

In the event of a fire, the chemical properties of intumescent paints or sealants undergo an endothermic process. In other words, a chemical reaction causes the materials within the paints to expand when exposed to high temperatures. This creates a protective coating for steel beams, columns and other building elements, without affecting their mechanical properties or basic functionalities.

Intumescent Paint Application

If a steel framework is coated with intumescent paint, the paint will expand into a carbonaceous char layer which solidifies once temperatures reach around 250°. This increases the steel’s fire resistance time whilst the building is evacuated. The exact performance of intumescent products can vary, offering 30, 60, 90 and 120 minutes of fire resistance depending on the specific type of coating.

There are several ways to apply intumescent products as part of a structural fire protection strategy, the most common being spray application as a thin film coating. Some varieties of intumescent paint can also be given a decorative finish. In this instance, we would engage with the manufacturer to ensure that all the coating finishes we use are compatible.

Intumescent coatings can be classified as either thin film or thick film. Thin film is the industry standard used to protect steel in buildings. In comparison, thick film intumescent coatings are mostly used to handle extreme temperatures in industrial environments, a common example being hydrocarbon fires.

Frequently Asked Questions

How much does intumescent paint expand?

The rate of expansion for an intumescent coating depends on its original thickness. Thin film intumescent 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 both the coating’s initial thickness and the rate of expansion.

What measurements are used when applying intumescent paint?

It’s important to note that intumescent paint is not measured in coats. The appropriate unit of measurement is the paint’s Dry Film Thickness (DFT). The recommended DFT can vary based on fire rating requirements and the type of paint, as well as the exact type and dimensions of the structural steelwork where the paint is being applied. We recommend you contact the manufacturer of your chosen paint if you have any specific questions about application and DFT.

What other materials can be protected using intumescent paint?

Intumescent paint is primarily intended for use on structural steel. While some types of intumescent paint can technically be applied to concrete, there is limited testing in this area. For this reason, we advise limiting the use of intumescent paint to steelwork.

How long does intumescent paint last?

The exact length of time can vary depending on the building’s lifespan, specific environmental conditions, and any damages or factors that may affect the intumescent paint (for example, any items in close proximity to the steel that may limit expansion). However, most water-based intumescent paints (once applied in a C1 environment) have a general lifespan of up to 20 years. It’s also worth noting that some types of intumescent paint will require top coats. This guide from Sherwin Williams outlines the life expectancy of various types of paint (subject to system and environmental conditions).

Does intumescent paint need to be maintained or reapplied?

Given the lifespan of the paint, intumescent paint does not require regular maintenance. However, it must be inspected regularly in the event of any damage to the paint. As a general estimate, if there is damage that exceeds the size of a £1 coin across an area of A4 paper then the paint needs to be repaired or reapplied.

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