What is Intumescent Coating for Steel?

Intumescent coating, or paint, is designed to swell to 50 times its own thickness when subjected to temperatures over 120°C. As the coating swells it forms a carbon layer which thermally insulates the steel structure it is protecting. The goal of an intumescent paint  application is to keep high temperatures, caused by fire, away from the steel members for between 30-120 minutes.

The critical failure point for the structural steel framework of a building is between 550 – 620°C. Once the steel reaches these temperatures it will begin to buckle and bend, with a high risk of collapse. The purpose of intumescent coating is to maintain the steelwork below this temperature, in a condition of ‘elasticity’. This describes a state in which the steel will bend or deflect, but will crucially return to its original form once the heat reduces.


Passive Fire Protection Includes Intumescent Coating

Intumescent coating is one of a range of products used to slow down, or prevent, the spread of fire in a building. Whilst active fire protection, such as sprinklers or extinguishers, require an active trigger to combat fire, passive fire protection is designed as part of the very structure of the building. The purpose of PFP is to allow time for an orderly evacuation of the building, and the maintenance of critical systems, in the case of fire.

Intumescent Coating is an Advanced PFP Product

Steel insulation has been a product in development for many years. The initial prototypes created a thick, spongy layer which had to be disguised. Intumescent paint offers the same level of protection, but the coating consistency gives the same appearance as a thin coat of paint. It is, therefore, preferred for its aesthetic finish, which incorporates a range of colour choices.

Intumescent paints are now a widely available, cost effective component used in the design of passive fire protection strategies. The Solvent and Water variations offer a range of fire ratings from 30 – 120 minutes, utilising thin and thick film intumescent technology. If a smooth finish is required the coating can be sanded down to achieve a finish identical to the steel it covers.

DunbarWallace Designs Passive Fire Protection

As specialist contractors, providing the design and installation of PFP strategies, intumescent paint is one of the passive fire products that are integral to our work. DWFP protects walls, floors and ceilings using a combination of:

Our PFP specialists will determine the passive fire protection design required to optimise orderly evacuation in case of a fire. We also have the capability to manufacture and install the products required to realise your PFP solution.


Reliable PFP for High Risk Environments

DunbarWallace has extensive experience designing and installing fire protection systems in some of the UK’s most high risk environments. Our firestopping designs can be found in power stations, transformer substations, nuclear facilities  and waste management centres. Whatever the environment we design for, our priorities are always the same; to deliver the highest standards of PFP, whilst achieving maximum efficiency, and maintaining our second-to-none health and safety record.


DunbarWallace has extensive experience designing and installing fire protection systems in some of the UK’s most high risk environments. Call us on 01525 864438