Intumescent paint for wood

Applied with intumescent paint for wood

Prevent wood from burning with intumescent paint for timber

We all know that wood burns first, yet it is a very common building material. Today’s technology, fortunately, allows a formula for intumescent paint for wood to make buildings safer also in case of fire.

Intumescent, what’s that?

Intumescence refers to the ability to expand when the ambient temperature rises to extremes. Intumescent wood paint is thus a coating which expands, and forms an insulating protection layer in the event of fire.

Applying intumescent paint for woods can be a smart move to protect your family and yourself from dangerous situations. The intumescent coatings for timber are suitable for wooden interior and exterior surfaces.

In this article we introduce the different applications, products and prices as well as explain the related standards and certification.

Benefits of intumescent coatings for wood

However, intumescent coating for wood does not prevent the structures from catching fire, it still drastically reduces the speed of burning. Wooden structures last longer and the timber does not collapse immediately, giving people valuable time to escape.

The coating upgrades timber surfaces to withstand fire for 30 or even 60 minutes.

Man spraying intumescent paint on wood

Applying intumescent varnish on wood walls.

Wood as a material catches fire easily but it is also a sensitive surface when it comes to weathering, UV exposure and humidity. Therefore, most of the intumescent paint systems also have other protective properties especially developed for wooden surfaces. These include:

  • Provides protection;
  • Suitable for untreated wood;
  • Insulates furniture, doors and flooring safely;
  • Upgrades existing doors, which is more cost efficient than replacing them in order to comply with the latest building regulations;
  • Applicable on already painted surfaces (primer usage prior to coating is mandatory in such cases);
  • Protects against UV radiation.

Intumescent paint for wood products & prices in the UK

The following table gives an indication on the intumescent wood paint prices in the UK. The price is given including VAT.

Brand Product type Price Packaging
 Bollom Intulac Ultra Basecoat  A fire protection varnish coating for interior wood surfaces.  £187.60  5 L
 Thermoguard Timbercoat Intumescent Paint for Timber  An intumescent paint system for bare and painted wood and timber derivative surfaces.  £114.00  5 Kg
 Rawlins Fire Door Paint  A kit of coatings containing primer, intumescent paint and undercoat for making doors last 30 min longer in fire  £140.02  4 door kit (2 sides per door)

Clear intumescent paint for wood

There are multiple different options for intumescent paint on wood. The coating is suitable for wood, lumber, plywood and timbers for interiors or exteriors. It can also be used as a wood sealer and then painted over; or as a top coat over pre-painted or pre-stained wood.

The intumescent coating for wood is usually a clear finish which retains the natural looks of the substrate.

Also the clear intumescent paint for wood inhibits treated material from igniting by creating a protective intumescent barrier between the heat source and the treated material. Once a heat source is present then the intumescent wood coating reacts with the heat and the intumescent function is triggered.

“Clear intumescent pain for wood exists as lacquer-like hard finish, preserving wood treatment and clear intumescent varnish for wood. It is one of the most popular fire preventing coatings due to the fact that it does not affect the appearance of the wood, but still provides appropriate protection from fire.”

Applying clear intumescent paint for wood

To reach a proper layer of clear intumescent varnish of wood, usually two different products are needed. There are however, also easy-to-apply one product systems on the market. The first coating should be a clear intumescent varnish for wood which thus, starts swelling when subject to high heat. The second layer in turn, should be a fire protective varnish which releases flame damping gas and protects the underlying clear intumescent varnish. It additionally defines the appearance of the layer; for it is available in several finishes such as matt, eggshell and gloss.

Door protection with varnish

comparison treated and untreated timber

Fire to treated wood (left) vs. bare wood (right)

Most intumescent wood coatings are also suitable for upgrading ordinary doors into fire doors. Usually the doors are treated with a clear intumescent varnish for wood, in order to retain the looks of the door.

Before applying intumescent varnish for doors, you should check whether the doors are suitable for becoming fire doors. The requirements are:

  • Solid doors, instead of hollow
  • Minimum door thickness of 35 mm

Is your door made of sunken panels?

Then the panel thickness and wood type matter. Softwood panels must have a minimum thickness of 16 mm whereas for hardwood panels 12 mm is enough. Are the panels thinner? No problem; you can buy a veneer kit to increase the thickness. However, the kits are applicable only for panels  of 9 mm or thicker.

Intumescent UK Standards

In the UK, the fire safety of constructions is controlled by the British Standard (BS) 476. The standard includes the required performance and flame resistance of certain materials. Intumescent products can contribute to reaching the level of resistance, therefore, the standard also includes coatings.

Ability to resist fire

The fire prevention properties of paint and coatings as well as other materials are measured by dividing the products into 30 minute and 60 minute fire prevention.

Thus, for example a 60 minute intumescent coat effectively stops fire and prevents it from spreading for 60 minutes.

BS class 1

Depending on the application, intumescent coating for wood must comply to some standards in accordance with the British Standards. The lowest standard is class 1 which requires that the coated surface does absolutely not allow fire to spread. The class 1 coatings are those applied in areas that have moderate risk for fire.

BS class 0

Class 0 requirements include class 1. They additionally state that the coatings must have very limited ability to catch fire and burn. The class zero coatings and other materials must have a low fire propagation index as defined by BSI BS 476 Part 6. The class 0 intumescent coatings for wood are suitable for applications in areas of high fire risk such as corridors and escape routes.


Are you going to apply intumescent timber coating yourself or do you wish to hire an applicator?

Whatever the case, you should get a certificate of the paint job. Many coating manufacturer’s and applicators provide product and application certificates. These may come in handy especially when agreeing on an insurance policy or claiming actual damage from the insurance.

Intumescent paint contractors throughout the UK

Area Company Address
England Fire Lining Systems Ltd 54 Hutton Close, Crowther Industrial Est , Washington , NE38 0AH
England, London area SIV Fire Protection Ltd Waterfront Business Centre, 57A North Woolwich Road,  London E16 2AA
England, London area Adept Contracts Ltd Unit C, Atcost Road, IG11 0EQ, Barking, Essex
Scotland A1 Sprayers 56-58 Jane Street, Edinburgh, EH6 5HG
Scotland Holemasters Scotland Ltd 114 Main Street, Chapelhall, Airdrie, Lanarkshire, ML6 8SB
Wales Sharpfibre Unit D1, Britannia Centre for Business , Pengam, Blackwood, NP12 3SP
Wales Taylor Engineering UK Ltd Unit 7 / 8, Curran Road,Cardiff, CF10 5NE

In case you wish to gain any additional information; detailed product and service prices, application possibilities or advice on certification and standards, our coating experts are happy to help you! 

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