Since 20 August 2024, new rules have applied to the reaction-to-fire class of timber cladding. Although the change may seem minor, with only the word 'untreated' added to the CWFT table, the consequences are significant for the use of timber cladding in construction. Below, we are happy to explain what has changed and what impact this has on your choices.
CWFT, or Certified Without Further Testing, is a European standard that, under certain conditions, places timber products directly in reaction-to-fire class D without the need for additional testing. Until recently, it stated that timber cladding met the requirements of fire class D if it involved a closed façade system with a minimum thickness of 18 mm and a density of at least 390 kg/m³.
Over time it became clear that the term 'wood' in the regulations was being interpreted too broadly, leading to incorrect assumptions about fire safety. The CWFT standards were never intended for treated or modified cladding. Yet this type of wood was often wrongly included under the standard. To avoid confusion and limit fire risks, Europe amended the standard and replaced 'wood' with 'untreated wood'. As a result, all treated wood varieties no longer fall under the CWFT table, and specific reaction-to-fire classification reports are required to comply with the standards.
With these amended regulations, architects, contractors and property developers must take a close look at the wood varieties used. Where the CWFT table previously offered a simple solution, additional fire tests and certificates are now usually required to guarantee the safety of treated or modified wood varieties. As a result, the choice of treated wood varieties for cladding must now always go hand in hand with the required fire certification.
Carpentier invests continuously in expanding its range of fire-retardant timber cladding. We currently offer two options to apply our timber cladding in full compliance with the current regulations, without compromising on fire safety or aesthetics.
Our range includes a varied selection of cladding in thermally modified wood varieties certified in fire class D, or even in fire class B, without a fire-retardant treatment. These closed profiles meet the new requirements and come with the necessary reaction-to-fire classification reports. These are available online and easy to download with your personal login.
A superb example of our HOTwood bamboo half-lap rebate QC as timber cladding can be seen in the Switi project in Amsterdam. This closed façade profile achieves fire class B-s1,d0 without a fire-retardant treatment.
For this biobased residential construction project, we supplied no less than 4,000 m² of this high-quality fire class B cladding. In the Netherlands, the project was awarded the National Timber Construction Award 2024 in the serial timber construction category, a recognition of its sustainable and innovative approach.
For projects that require extra fire safety, we can provide an additional fire-retardant treatment to the desired reaction-to-fire class on a number of timber cladding profiles. The wood is then treated in an autoclave under vacuum pressure with a fire retardant based on 100% natural ingredients.
In the second half of 2026, in collaboration with the company Grad, we will launch a new fire-resistant clip. Thanks to this innovative development, subject to a fire-retardant treatment, we will be able to achieve fire class B even for open façade systems and ceiling panelling with gaps of up to 30 mm. A solution that makes it possible to combine the aesthetic benefits of open systems with the required fire safety.
Unsure about the right profile, the best finish or the appropriate accessories for your project? Our timber specialists are happy to share their expertise and help you choose the right solution.
