New fire regulations for wood cladding

19/08/2024

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.

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 information 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.

Download flowchart

Meet D-s3,d1 with untreated wood

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.

The conditions

1. Profile for closed wooden cladding

2. The cladding profile is flat or ribbed:
> Flat: a min. thickness of 18 mm is required
> Ribbed: a min. thickness of 18 mm and a min. thickness of 12 mm on the thinnest part is required (on max 25% of the profile area)

3. The wood species must have an average density of at least 390 kg/m³.

4. The cladding must be installed on a substrate with fire class A2-s1,d0 (= non-combustible) with a minimum density of 10 kg/m³ (e.g., mineral wool insulation).
PIR and PUR do not have a fire class A. In that case, it is necessary to add a panel with fire class A2-s1,d0.

Any deviation from the above conditions must be tested.

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Meet D-s3,d1 with treated wood without testing

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.

According to the new rules of August 20, 2024, the 'treated wood product' 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 products.

You can avoid these tests by treating the wood with a fire retardant or choose from a certified range of LDCwood^® ThermoWood^®.

Lemahieu Fire Protection offers a wide CE certified range

Lemahieu Fire Protection's fire-retardant treatment impregnates the wood under vacuum pressure with the fire retardant Burnblock^® and thus meets B-s1,d0 (better than D-s3,d1). The fire-retardant treatment can also be combined with a pre-weathering or color as a surface treatment.

And meet these conditions:

1. Closed cladding in LDCwood^® ThermoWood^® with tongue and groove or overlap

1. Average wood density between 380 and 1000 kg/m³

2. Flat profiles with a minimum thickness of 18 mm

3. Vertical or horizontal installation, mechanically fixed on wooden battens (softwood, density of 450 kg/m³)

4. Ventilated air gap with a minimum thickness of 38 mm

5. 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.

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Processing

Wood protection

Fire protection

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NEWS

New fire regulations for wood cladding

Cladding

Wood preservation

Meet D-s3,d1 with untreated wood

Meet D-s3,d1 with treated wood without testing

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

The new rules in a handy flowchart

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