As of August 20, 2024, the rules for the reaction to fire classification of wood cladding changes. In this article, we explain the implications and what you need to consider.

Download the flowchart

The reaction to fire class of wood cladding is determined by the height of the building and the type of user. In the new regulations, there are no changes for buildings over 10 meters high. These buildings must still meet at least reaction to fire class B-s3,d1 (< 25 m) or a large-scale test (> 25 m).

More info about the fire requirements

For low buildings (except for single-family homes and industrial buildings), the rules have changed when it comes to sleeping self-reliant users (type 2; e.g., hotels and apartment buildings) and awake users (type 3; e.g., office buildings, shops). The reaction to fire class must meet D-s3,d1.

Distinction between treated and untreated wood for reaction to fire class D-s3,d1

Until recently, for wood cladding, you could rely on the CWFT table (Certified without further testing): any wood species and wood profile that met the conditions of the CWFT could be used as cladding without requiring a test and/or classification report. However, the European Commission has now determined that the CWFT table only applies to 'untreated wood products.'
 

Untreated wood

is wood has not been preserved through impregnation, has not been thermally or chemically modified, and/or has not received any surface treatment such as oil, paint, or varnish, etc.

Treated wood

is wood that has been preserved through impregnation, thermally or chemically modified, and/or received a surface treatment such as oil, paint, or varnish, etc.

Project: Residention Prosper Park - facade cladding in LDCwood^® ThermoWood^® Ayous fire retardant treated with Burnblock^® by Lemahieu Fire Protection^®

Good news for ThermoWood^® from LDCwood^®
(without fire-retardant treatment)

The thermally modified products of LDCwood^® ThermoWood^®  fall under the category of 'treated' wood. According to the new rules of August 20, 2024, the 'treated wood' must be tested to determine if the facade construction meets the required reaction to fire class. You can no longer simply rely on the CWFT table when choosing 'treated' wood.

However, LDCwood^® ThermoWood^® offers solutions (without surface treatment) that meet the reaction to fire class D-s3,d1 without fire retardant treatment and without tests.

Choose from one of these wood species:

• ThermoWood^® spruce
• ThermoWood^® pine
• ThermoWood^® fraké
• ThermoWood^® ash
• ThermoWood^® Red Oak
• ThermoWood^® Radiata Pine

And meet these conditions:

• Closed cladding in LDCwood® ThermoWood® with tongue and groove or overlap
• Average wood density between 380 and 1000 kg/m³
• Flat profiles with a minimum thickness of 18 mm
• Vertical or horizontal installation, mechanically fixed on wooden battens (softwood, density of 450 kg/m³)
• Ventilated air gap with a minimum thickness of 38 mm
• Substrate behind the air gap composed of
  • wood-based panels (class D-s2,d0 or better, minimum thickness of 10 mm, minimum density of 510 kg/m³) or
  • non-combustible panels (class A2-s1,d0 or better, minimum thickness of 10 mm, minimum density of 510 kg/m³)

Any deviation from the above wood species and conditions must be tested.

A rain screen (<1 mm) has no significant impact on the reaction to fire class of closed cladding.

*Tests and classification report WFRGent nr. 19763G.

And what about coated ThermoWood^® (with surface treatment)?

If you want coated (varnished, painted, oiled, ...) ThermoWood^® from LDCwood^® as cladding, you should normally have tests done.

You can avoid these tests by having the coated ThermoWood^® fire retardant treated. We have a wide CE certified range for this.  The fire retardant treatment under vacuum pressure is done at the same production site as the thermal treatment.

Our certified offer

The new rules in a handy flowchart

 

 

We mapped out the different situations of the required reaction to fire class using a flowchart.

 

Download the flowchart

Still not entirely sure?

To comply with the new fire regulations, we recommend our customers and architects to contact us. Together, we will review the project in detail and provide advice on the solutions.