Intumescent Paint for Steel

How does intumescent paint work on steel?

Intumescent paint expands when exposed to high temperatures, forming a thick, insulating char layer that slows heat transfer to the steel. This delays the point at which the steel reaches its critical failure temperature, helping maintain structural integrity. The coating remains unobtrusive under normal conditions, preserving the appearance of exposed steel while offering essential fire resistance.

Can I paint over steel intumescent paint?

Yes, steel intumescent coatings can be overpainted with a compatible topcoat to improve durability, especially in areas exposed to moisture, chemicals, or mechanical wear. The topcoat should be fire-rated and approved for use over intumescent coatings to ensure fire protection properties are maintained. Always follow manufacturer guidelines and data sheets to ensure compliance and long-term performance.

Can I use intumescent paint on exposed steel beams in my home?

Yes, intumescent paint can be applied to exposed steel beams in residential properties to improve fire safety. With over 4,400 colour options, the coatings can blend with a home’s interior design while providing essential fire resistance. Homeowners should ensure the chosen product meets fire regulations and is applied correctly.

How do you apply intumescent paint to structural steel?

Intumescent paint can be applied by brush, roller, or spray. The steel surface must be cleaned and primed before application to ensure proper adhesion. The paint is applied in multiple coats to achieve the required dry film thickness (DFT) – measured during application using a Tricomb Plastic Wet Film Gauge - which determines the level of fire resistance. Following the manufacturer’s instructions for drying times and thickness is crucial for effective fire protection.

Is intumescent paint suitable for exterior steelwork?

Yes, but it requires a weather-resistant topcoat for protection against environmental exposure. UV rays, moisture, and pollutants can degrade unprotected intumescent coatings. Applying an approved protective topcoat helps maintain durability and ensures continued fire resistance. Regular maintenance is recommended to assess coating integrity and reapply protection as needed.

How to Get A Quote or Full Calculation/Specification to Meet Building Regulations

Simply call us (mobile users can click on this number 0113 245 5450) and let us know:

• Level of fire protection required (i.e. 30, 60, 90min, etc.)
• Each steel section dimension (i.e. 254x146x37 UB)
• Quantity and length of each section (or overall meterage for each section)
• Orientation (horizontal or vertical)
• Number of sides to be painted (all sides, 3 sides, 1 flange, etc.)
• Environment (internal, external, car park, chemical exposure, etc.)
• Application on site or in shop

Alternatively you can just forward us drawings (email [email protected]), fabrication/cutting lists and we'll extract the information from them but in that instance we'd need some guidance as to what to allow for i.e. all steels on first floor, etc.

We will then generate a full report including specification and mark-ups (where relevant) providing you the most cost effective solution available for your project, which includes:

• Cost (including trade discount)
• Typical coverage rates
• Product application instructions
• Product storage instructions
• On/off-site product transportation recommendations
• ETA on product delivery – and whether next day delivery options are available with your purchase
• Product and full system recommendations or requirements
• Surface and substrate preparation advice
• Including usage for new steel, and painting over/preparing previously decorated surfaces
• What coating finishes may be available for improved decorative and aesthetical value
• Drying times and times between coating layers

Certificates

All of the intumescent paints we offer have been tested to varying British/European standards by recognised independent third parties depending on their required use and performance. In addition to these industry standard tests, some products also offer additional paperwork after use by way of a ‘certificate’ that can be obtained in different ways - manufacturer dependent. Some require a form to be completed and returned by email, others have online application forms, others can be simply called to provide project details verbally. Not ALL products offer this additional supplement and if this type of certificate is important to your project you should contact our Technical Team on 0113 2455450 (option 2) or [email protected] to advise them of this so they can ensure they recommend a suitable product accordingly. Certain larger projects may also require the involvement of an independent inspector, again you should contact our Technical Department to discuss this if required.

Our help and advice promise

Fire protection doesn’t have to be hard work, let our technical staff help you get the level of protection you require and the finish you want. Whether it’s structural steel in a warehouse, fire retardant paint for wood on a new-build, or the internal walls of a block of flats, we can provide a full specification and offer guidance throughout the project.