intumescent paint

Intumescent paint is passive fire protection 

Aside from active firefighting measures such as alarms and sprinkler systems, there are passive firefighting measures you can undertake to protect against fire. Some of these are the use of fire resistant and fire retardant paints. Intumescent paint is the former; a paint which resists fire by swelling up when exposed to extreme heat. Intumescent coatings are suitable for softwoods, hardwoods, brick, MDF, tiles, steel, concrete, plaster, and many other surfaces. 

In this article we look at how intumescent paints protect in the case of a fire, as well as the costs, suppliers, and British regulations related to passive fire protection.

The advantages of intumescent paint

When exposed to temperatures of 200-250ºC, intumescent paint undergoes a reaction and expands to up to 50 times its original size. This forms a foam-like solid called a char, which insulates the underlying substrate from the heat and fire for up to 120 minutes, providing invaluable extra time to evacuate or get the fire under control. In this way, intumescent coating is part of a building’s fire protection system.

An intumescent paint system provides double the protection

An intumescent paint duplex system provides double the protection

While advantages like insulation against fire are obvious, intumescent paints have other advantages including:

  • Easy application
  • Cost efficient
  • Maintaining the structural, aesthetic and architectural value of a building
  • Can be used on interior and exterior structures
  • Will strengthen the building and prevent substrates from burning, melting and weakening in fire
  • Can be combined with fire retardant paint to form an even more powerful duplex system

Combing intumescent paint with a top coat of fire retardant paint greatly increases your fire protection. The fire retardant paint works by releasing a flame damping gas, impeding the spread of the flames and extending the time til the intumescent layer is triggered. Together the two layers work to provide the highest degree of protection.

Intumescent coatings for all substrates

The advantages of intumescent coating vary depending on your substrate, with products providing added protection or features tailored by material. All of them insulate against fire, but some include added extras.

  • Wood: Fire resistant paint for wood provides weathering and UV protection.
  • Steel: Fire resistant paint for steel is often rustproof, as well as prolonging the life of steel by insulating it against temperature fluctuations.
  • Concrete: Intumescent coating helps concrete retain its strength, and like with steel, protects it from structural and load-bearing damage caused by fire.

One of the greatest benefits of intumescent paint is its flexibility, not just with substrate but also application. Intumescent painting can be done with a brush, roller, spray, on site or off site, on structural elements and walls.

Fire safety regulations in the UK relating to intumescent coating

Building regulations and standards mandate fire resistant coatings in buildings

Building regulations and standards mandate fire resistant coatings in buildings

In the UK the responsibility of providing fire safety in business and other non-domestic premises is given to the employers, owners, landlords and other parties in control of the premises. To assist them the governement provides a guide for making premises safe from fire, and the British Standards Institute lists the standards expected of fire resistant materials in  BS 476 Part 6.

BS 476 divides intumescent coatings into class 1 and class 0 coatings. Class 1 is the lower standard, though even this requires that the coatings and other construction materials do not allow fire to spread. Class 0 includes the specifications for class 1 but adds the requirement that the materials have a very low tendency to propagate a fire. Intumescent coatings can also be classified by the length of protection they offer. So, a 30 minute fire rated coating should provide 30 minutes additional time between the fire breaking and taking hold.

When applying intumescent coatings, you should always make sure the product and coating job are certified. Many service providers and intumescent coating manufacturers provide a certificate together with the service or product.

Intumescent paint cost UK

If you want to get the best coating for your project we advise you to request a quote and have your intumescent painting done by a certified professional. These figures are just an indication to give you a rough guide as to the intumescent paint cost per m². Prices are for the UK and include VAT. The cost of intumescent paint will vary depending on project and substrate requirements.

3MScotchkote Intumescent Coating LS1000 £33020L6.7m²/L
AkzoNobel International Interchar 212 £75020kg1m²/kg at 1mm thickness
Bollom Intulac Ultra Basecoat £200 5L 5m²/L
BollomFireshield Ultra Universal£360-370 10L Dependent on layer thickness
Crown TradeTimonox Upgrade Basecoat £120-130 5L2.5m²/L
Jotun Steelmaster 60WB £150-16018.5L 1.4m²/L
NullifireS707 Water-Based Intumescent Basecoat£140 25kg 700g/1m² at 0.5mm dry film thickness
Sherwin-Williams Firetex FX1003£330-340 20LDependent on layer thickness
ThermoguardThermocoat W £26020kg Dependent on application method
Zero Flame Aquasteel WB +£17510LDependent on application method


Intumescent paint suppliers and manufacturers in the UK

As the popularity of intumescent coatings increases, so too does the number of products and manufacturers. Here are just a sample of  intumescent paint suppliers and manufacturers whose products are available in the UK.

Akzo Nobel International, Interchar
Bollom Intulac, Fireshield, Broflame, Brosteel
Crown TradeTrimonox
Envirograf All products
Jotun Steelmaster
Nullifire All products
Sherwin Williams Firetex
Sika Unitherm
Thermoguard All products
Zero Flame All products
FPCL Intumescent coating products

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