Intumescent paints

Construction professionals will be aware of Intumescent paint but may not know the most efficient and effective way to apply it to steel materials on large projects.

Since the Grenfell Tower fire in 2017, there has been a review of the National Structural Steelwork Specification (NSSS). The British Constructional Steelwork Association (BCSA) has released new guidelines which strongly suggest the use of factory-controlled application of intumescent paint. This is to ensure that the environmental and application controls necessary to meet the safety requirements are in place. Intumescent paints are used to protect steelwork from fire damage, and it is essential that they are applied in a controlled environment to ensure their effectiveness. Without these controls, the risk of fire spreading is greatly increased.

The BCSA has also released a document outlining best practices for intumescent paint application. This covers everything from surface preparation to final inspection and includes detailed instructions on how to apply the coatings correctly. It is essential that all those involved in the application of intumescent paints follow these guidelines to ensure that the steelwork is properly protected.

Why Intumescent paint?

For those that don’t know, Intumescent paint is a specialist coating that swells up when exposed to heat, forming a char that protects the steel underneath from fire. Protecting the structural capabilities of the steelwork to help prevent building collapse.

Intumescent paints can increase the time possible for evacuation by up to 50% in cases where there is a fire because of the protection they provide.

Intumescent coatings are available in both water-based and solvent-based formulations and can be applied in various coating systems to provide the necessary fire protection required.

Intumescent Paint Features

Intumescent paint provides a specialist coating that expands when exposed to high temperatures and forms an insulating intumescence layer on top of all material surfaces within reach – thus protecting them from any further heating effects.

Ultimately, they act as an insulator between metallic surfaces and flames/heat sources protecting them against further thermal effects which cause their structural capabilities to fail.

High-temperature exposure leads intumescent paint to solidify – Intumescent paint can expand up to 100 times its original size when exposed to extreme heat. This “solid” intumescent layers of material acts as a barrier that protects any surface materials from further damage until the flame/heat source is completely removed.

Intumescent Paint Application

Traditionally intumescent paints have been applied on site in an array of conditions that influence their effectiveness. Now, new industry guidance insists on in factory application of intumescent paint. Allowing for controlled drying times, temperature control, even application, inspections and most importantly it allows each section to be coated independently allowing full, even application that would otherwise be difficult to achieve once erected onsite.

These controls allow for quicker, more accurate and more cost-effective solutions to the traditional onsite application of Intumescent painting.


Midland Structures is one of the first UK structural steel fabricators with the ability and facilities to provide intumescent painting in factory-controlled conditions as part of a full manufacturing service.

Our new dedicated intumescent painting facility has now been approved by Sherwin Williams to provide any level of fire protection using intumescent paint.

At Midland Structures, we are experts in the fabrication of structural steelwork, and now with our new intumescent painting facility, we can provide a one-stop-shop for all your steelwork needs. So, if you require intumescent painting for a current or upcoming steelwork project, get in touch with us today.