FAQ – Treating wood with fire retardants

Author Arto Nummela l Group Portfolio Development Manager Jun 25, 2020 8:30:00 AM
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Wood construction is on the rise in Finland, with many beautiful and sustainable wooden apartment buildings, libraries, and schools built in recent years. Promoting wood construction has been part of the government program since the 1990s, and it has been suggested for inclusion in the next program too.

Regulations regarding wood construction, including fire safety regulations, have been updated over the years. Tikkurila offers various products for fire protection, and in this post we’ll answer many of the most frequently asked questions about fire protection and fire-retardant products.

What’s the benefit of using fire-retardant products?

Fire retardants slow the ignition of wood and the spread of fire, while also creating less smoke than untreated wood. This provides valuable extra time for people to escape and for emergency services to reach them, while reducing the effects of smoke inhalation.

How do fire retardants work?

When exposed to heat, fire-retardant material expands and creates an insulating foam layer on the wood. The porous foam layer insulates the wood from the flames, preventing the wooden surface from heating up rapidly or catching fire. This is known as intumescent technology, i.e. fire protection based on the paint surface expanding when exposed to heat.

Compared to salt-based fire-retardant products, surfaces treated with intumescent technology can better withstand moisture, UV light, and weather.



What are the differences between intumescent technology vs salt-based products?

Comparison table intumescent vs salt

Which wooden surfaces need fire protection?

Generally speaking, wood can be used as a construction material without fire-protection treatment. However, depending on the site and customer requirements, treatment can make the building safer. This extra protection enables a wider use, for example in the following types of buildings:

  • Schools, kindergartens, and assisted-living facilities
  • Storage facilities
  • Detached houses, terraced houses, and apartment buildings
  • Offices
  • Hotels
  • Libraries
  • Annexes or extra floors with wooden frames

Check the local fire-safety guidelines for wooden houses, with information on the type of fire-retardant classifications required for various exterior and interior surfaces. Surface classifications (such as walls, ceilings, floors, and outside lining) vary depending on the space (e.g. floor, cellar, bathroom, exit).

Can fire retardants be used with all types of wooden surfaces?

For less-common types of wooden material, please get in touch with a Tikkurila expert before applying a fire-retardant paint. You can get in touch with an expert here

What types of fire-retardant materials does Tikkurila offer?

We currently offer the following products for fire protection:

  • Fire-retardant paint for interior surfaces (Fontefire WF)
  • Fire-retardant lacquer for interior wooden surfaces (Fontefire WF Clear)
  • Chemical-resistant surface lacquer for fire-protected surfaces that need to withstand cleaning with common household chemicals (Akvilac WF 10)

Are fire-retardant paints and lacquers environmentally friendly?

Yes, Tikkurila fire-retardant products contain no ingredients that are hazardous to humans. And since they are waterborne, they cause less emissions and are environmentally friendly and safe to use. Our fire-retardant products have been developed for industrial painting, meaning the surface treatment takes place at the factory under controlled conditions rather than at the construction site. This ensures emissions are reduced even further and prevents fugitive emissions on site.

Tikkurila’s fire-retardant products carry the B-s1, d0 fire safety classification. What does this mean?

B-s1, d0 is the best possible fire-safety classification for wooden materials. Construction products and building elements are divided into various fire classifications according to the EN 13501-1 European fire safety standard. The classification also includes an A class, reserved for non-combustible materials such as steel.

Here’s a more detailed listing of the fire classifications for construction materials:

Construction materials are labeled with the following markings, with the exception of flooring: A1, A2, B, C, D, E, F.

Smoke emission and flaming droplets are identified with the extra classifications “s” and “d”. For smoke emissions the classifications are s1, s2, and s3, and for flaming droplets d0, d1, and d2.

A1 = Materials that do not contribute to fire at all (non-combustible materials)

A2 = Materials with extremely limited contribution to fire

B = Materials with very limited contribution to fire

C = Materials with limited contribution to fire

D = Materials with acceptable contribution to fire

E = Materials with acceptable fire behavior

F = Materials with no defined type of fire behavior

s1 = Very low smoke emission

s2 = Low smoke emission

s3 = Smoke emission does not meet s1 or s2 requirements

d0 = No flaming droplets or particles

d1 = Flaming droplets or particles burn out fast

d2 = Production of flaming droplets or particles does not meet d0 or d1 requirements


Source: E1 National Building Code of Finland

For more information about fire classifications, please see the Puuinfo technical data sheet on fire classifications for surfaces and roofing materials.


What color is Fontefire WF fire-retardant paint?

The paint is light gray, adding to the covering properties of the entire paint surface.

Can a wooden surface be painted first and then the Fontefire WF Clear fire-retardant lacquer applied on top?

No. Fontefire WF Clear must be directly applied onto the wood without any priming lacquers in order to meet the requirements for the B-s1, d0 surface classification. 

Fontefire WF Clear is transparent white. Tikkurila’s fire-retardant products are intended to be applied directly onto the wood. If surfaces are first painted or tinted the fire-retardant properties will not necessarily work as intended. Additionally, the light surface lacquer will cause light to refract, creating a hue for the underlying surface that is not necessarily what the customer wanted.

Can Fontefire WF Clear be tinted?

No. The fire-retardant classification is only approved for clear lacquer, not tinted.

Can Akvilac WF 10 surface lacquer be tinted?

Not at the moment, though we are currently testing a tinted surface lacquer to investigate how well the fire-protection properties are maintained when tinting.

Can you paint over Fontefire WF products with any paint?

No. The fire-retardant classification is only retained if one of the following products is used as a topcoat:

  • Akvi Top DS 25 (interior)
  • Akvilac WF 10 (interior)

Do fire-retardant products always need to have a topcoat?

If a fire-protected surface needs to be abrasion resistant, it should be finished with a top lacquer or paint.

Indoors, a fire-retardant lacquer alone is sufficient for wood surfaces that are not subject to wear, such as ceilings.

How should fire retardants be applied to wooden surfaces?

Fontefire WF products are developed, and primarily intended, for industrial painting. In addition to vacuum application, spraying, and curtain coating, the products can be applied onto small surfaces with brushes or rollers. Only industrial paint shops currently hold valid fire-retardant certifications.

If there is an air gap in the structure, can panels or boards be treated with Fontefire WF Clear fire retardant?

No. For special circumstances please always consult a local fire protection specialist.

Topics: Wood Fire Protection

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