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Read more about some important areas of knowledge that are important to know about fire protected wood


Choice of method

There are two main methods for fire protecting wood: fire impregnation and fire protection paint.

Fire rating

The fire resistance of building components and structures can be classified into different fire technology classes or combinations thereof.


All types of materials are worn down over time, so life-long issues and durability become important factors in material selection.

Legal requirements

Buildings shall be designed with such fire protection that fire safety will be satisfactory and take into account that fire may occur.


Fire-protected wood is a material choice with strong arguments within all three sustainability dimensions: environmental, economic and social

Documentation requirements

Fire protection is an area surrounded by a lot of legal requirements, and it is important to know the documentation requirements that are set.








Wood types



Below you will find the most common questions in the area of fire protected wood


Yes, CE marking is a legal requirement from the EU. All requirements can be found in the EU Construction Products Regulation CPR 305/2011 and apply to both solid wood and wood-based panels. For fire impregnated wood, the manufacturer must hold a Certificate of Constancy of Performance (CE certificate) according to control system 1, unlike regular untreated wood, for which the manufacturer can issue a Declaration of Performance according to control system 4.

If a panel is installed with an air gap despite the fact that the fire class prohibits it, you have a problem. In order to use a fire retardant treated wood panel, the additions described in the CE marking appendix must be taken into account. It is not allowed to perform an instalment with spaced boarding when the opposite has been approved, i.e. an installation where there is no air gap.

The fire classification of a material takes into account various properties that each may contribute to the performance of the product; these may for example be physical properties of the material such as density, thickness, air gaps, exposure, surface treatment, instalment conditions, etc. It is common that customers only look at the fire class, eg. B-s1, d0 while other important properties are forgotten. It is therefore important to pay attention to the importance of the air gap.

If a wood panel is installed without an air gap directly on plaster, smoke generation decreases even if the fire spreads through the wood panel. If, however, there is an air gap, then the fire will go directly through it and double the area on which the smoke is spread. This means that a fire class B-s1, d0 may as well become a B-s2, d0 or in the worst case a B-s3, d0. Smoke is the most common cause of death in a fire, so the question of air gaps is much more important than many people think — if not completely vital.

The decision to install spaced boarding must therefore be made by considering all verified properties so that the correct fire rating is achieved, including the air gap.

An exterior wooden panel is exposed to weather daily. This places high demands on the fire retardant treatment agent that must remain intact and not be leached. The active ingredients in the fire retardant treatment agent therefore play a crucial role when the wood panel is to be used in an outdoor environment.

The point of impregnating a wood panel with a fire retardant treatment agent is to provide lasting protection against fire. The active constituents in the agent also have a task that is equally important which is to withstand the test of time; they must provide long term durability and not wear off.

Fire retardant treatment and durability are two factors that must be taken into consideration regardless of whether you are in the regulatory or executive phase.

Below, you will find the most important factors to consider in order to ensure fire safety in a humid environment.

  1. Are the active ingredients in the fireproofing agent water soluble?
    The simpler the composition of the fireproofing agent, the greater the risk that the fireproofing agent is leached. An example of a highly soluble fire retardant treatment is ammonium phosphate.
  2. Are the substances hygroscopic? In other words: Do they attract and absorb water from the air?
    If this is the case, the substances may be drawn out of the wood, which then loses its reaction to fire properties. This phenomenon is more commonly known as salt leaching and is a consequence of a simpler fireproofing agent composition.
  3. Is the fire retardant treated panel installed outdoors?
    A house facade is exposed daily to the effects of the weather. Rain of varying intensity, snow, fog and other frequent wetting cause water flows on a treated facade that may lead to the active substances being leached to the ground and to streams. At a time when environmental awareness and durability are important, it is unwise to use fire impregnated wood panels that do not have permanent smoke and fire properties. The fire retardant treatment must be approved according to the EN16755 EXT.
  4. Are you prepared to clean the facade from leached fireproofing agents?
    There are several examples of how it can look when the fireproofing agent has began to leak through the facade; it can look like someone has sprayed foam on it when fluffy, yellowish-white crystals start to appear, at which point it is time for the facade to be cleaned. Has this cost been included in the budget?

Fire safety is about so much more than a fire class. Therefore, avoid investing in a fire retardant treated wood panel that does not have adequate durability of reaction to fire properties. By using fireproofing agents that cannot cope with the challenges that arise over time, the life cycle cost of the building will be increased due to an increasing need for future renovations.

Euroclass B refers to the product's reaction to fire properties according to the classification standard EN13501-1. Regular untreated wood meets D-s2, d0 requirements, while some fire impregnated products meet B-s1, d0 requirements. The SP-Fire 105 refers to an exterior wall cladding that has been fire tested according to the principles of facade construction.

A classification typically clarifies the result of a fire test, while a certification is an official approval of the product when done in accordance with a specific product standard. A certified product is always covered by manufacturing control and quality assurance, while a classified or fire tested product is not.

Contact a fire consultant. The rule of thumb is that tall wooden facades (more than two storeys), escape routes, roof and wall claddings of public buildings, sports facilities, community centres, etc. must be fireproofed. Seek advice from a renowned fire consulting company just in case.


Take note of interesting fact articles in the area of fire protected wood

Durability - a vital part of satisfactory fire protection

The durability of the fire protection can be literally vital. If there is a shortage in durability, people live in false security.

Building more with wood is good for sustainability

Wood is a material with many environmental benefits.

Myths about fireproof wood

If not all involved parties (manufacturers, buyers, fire consultants, architects and builders) take their share of the responsibility for this, it