Three key points to know about fire safe wooden panels

The benefits of avoiding fire retardants.

Looking for fire safe wood panels? In this article we highlight three important points for architects to understand when specifying wood panels for a project, and why fire retardants aren’t the only route to a safe and beautiful wood interior.

Material composition matters

Despite its many natural benefits, wood is a combustible material. When specifying wooden panels or ribs for a project, it’s always important to consider fire safety at an early stage in the process, and there are a couple of options to consider.

Perhaps the first option that comes to mind is to use fire retardants to improve the fire performance of a wooden cladding. However, when considering material composition and reaction to fire, it’s important for architects to understand that another route to safety is to avoid combustible materials, giving you peace of mind.

This can be achieved because panels made of non-combustible materials, such as fibre gypsum, can be clad in a real wood veneer, and still retain their ‘non combustible’ classification, according to the EN 13501-1 Reaction to Fire standard. The A2 rating within the EN 13501-1 standard allows for a very small percentage of combustible materials, and that’s where the natural wood veneer comes in.

Utilising non-combustible materials as the main component within the panel is generally a more reliable method than fire retardant-treated solutions, and it can achieve a higher fire rating. Furthermore, as you’re not adding any chemical treatments to the surface of the cladding, you don’t have to worry about any potential negative effects on indoor air quality.

Understanding the whole product in its final form

Another important point to know is that fire ratings are only valid when the whole product is used, in the shape and form in which it was originally tested. Therefore, you need to understand the performance of the complete product you’re specifying, including for example surface layers and finishes, installation systems, and factory post treatments such as perforations.

In an interview about fire safety in wooden interiors, Anders Bach Vestergaard, Senior Fire Specialist at the consulting group COWI, explained the importance of understanding how each element burns, saying that “Tweaking just one variable might sound insignificant, but it can substantially affect how the product reacts to fire – especially in the case of solid wood and fire retardant-treated wood solutions.”.

When fire retardants have been used, the fire safety of the cladding isn’t achieved through the material composition, but through a treatment added to the surface of the material; for example impregnation or lacquer.

Therefore, when considering the performance of the entire product, questions may arise in relation to whether a panel or rib has been impregnated uniformly throughout the thickness of the material, how the treatments perform together with perforations in acoustic panels, or whether the impregnation loses its performance over time due to hygroscopicity (absorbing or attracting moisture from the air) and leeching (loss of the fire retardant chemicals).

The reliability of the performance is reflected in the requirement for production controls.

All European construction products with a CE marking must have a Declaration of Performance (DoP). The DoP explains the characteristics of a product, including their reaction to fire classification, helping architects and developers understand how each building product will perform. All manufacturers should be able to share the DoP for their products, and it’s important to ask for these.

To make sure that the composition and manufacture (and therefore the performance) of a building product doesn’t change over time, the DoP includes details on the constancy of performance. This is controlled by The Assessment and Verification of Constancy of Performance (AVCP). Depending on the characteristics of each building product, there are different levels of annuals production controls that need to be carried out by the manufacturer or a third party ‘notified body’.

When it comes to claddings with a non-combustible material composition, no instances of production control by notified bodies are required. Minor discrepancies in the production and material composition are considered to be inconsequential to the final fire performance and classification of these products.

On the other hand, wood panels manufactured from solid wood, plywood or MDF, and improved by fire retardants, fall under another control system, and therefore require yearly production controls by a notified body. For these products, even small discrepancies within the production process can have large consequences for their final fire performance. Furthermore, it is not possible to visually control the fire performance of the final product; it is for example impossible to see if an impregnation has been applied correctly or not.

It’s also important to note that CE markings cannot be given for products that have been treated in a non-controlled process, for example on site with fire retardant coatings.

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