Fire Rated
Timber Cladding

Fire retardant timber cladding combines natural wood with certified fire performance, using fire retardants to reduce flame spread and enable safe use on walls and ceilings in demanding locations.

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What is Fire Rated Timber?

Fire rated timber is produced by applying fire retardant treatments that reduce how the material reacts when exposed to fire. These treatments slow flame spread and reduce heat release, allowing the timber to achieve a classification under European fire standards. The level of performance achieved depends on the timber species, board profile, treatment system and overall façade build-up. Fire retardant systems alter how timber behaves under heat. When exposed to fire, the treatment promotes the formation of a protective char layer and reduces the release of combustible gases.

This helps slow the spread of flame across the surface and limits the contribution of the timber to fire development. When tested as part of a classified system, treatments can also influence smoke production and the formation of flaming droplets.

Reduces flame spread across the surface
Limits heat release
Promotes protective charring
Reduce smoke and droplets depending on classification

Corell offers two fire retardant approaches depending on project requirements, specification and desired finish

Fire retardant treatments can be applied using either pressure impregnation or factory-applied systems, depending on the project requirements, cladding profile and desired finish.

Pressure treated systems allow the fire retardant to penetrate through the timber section, providing a consistent level of treatment throughout the board.

Factory-applied systems are absorbed into the surface of the timber rather than forming a film. This allows the timber to retain a natural appearance while achieving fire performance when tested as part of a system.

All treatments are carried out under controlled conditions to ensure consistent application and reliable performance across the boards. Systems are selected based on the required classification, façade build-up and project specification.

Fire retardant treatment can be applied to Avara® Clear and Avara® Character, and can also be accommodated on specified Yakisugi cladding, depending on system and finish requirements.

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Fire Classification

Fire rated timber is tested and classified in accordance with EN 13501-1. Typical classifications for treated timber can include Euroclass B or C depending on the timber, treatment system and installation.
Classifications may also include indicators for smoke production (s) and flaming droplets (d), which are only valid when tested as part of the complete system.

Final performance is influenced by:

Timber species
Board size and profile
Fixing method and cavity design
Treatment system used

Fire performance should always be considered as part of the full façade build-up rather than the timber alone.

Design & Specification

The selection of a fire retardant system should align with both performance requirements and the intended appearance of the façade. The interaction between timber, coating systems and installation method should be considered at design stage.

Key considerations:

Required fire classification
Exposure conditions
Compatibility with coatings
Profile and board thickness
Installation method and build-up

maintaining a finish on fire treated timber cladding

Maintaining the Timber Finish

Fire retardant treatments allow timber to retain a natural appearance. Pressure treated systems maintain a more untreated timber look, while surface-applied systems allow greater flexibility where colour or coatings are required.

The final appearance will depend on the timber species, texture and finishing system used.

Fire Rated Timber at Corell

Fire retardant treatments can be applied to Avara™ Clear and Avara™ Character, allowing fire performance to be achieved without stepping outside the core cladding range. Both grades can be processed using either pressure treatment or factory-applied systems depending on the project requirements.

Fire retardant treatment can also be accommodated on specified Yakisugi cladding, subject to system selection, profile and finish requirements. This allows charred finishes to be considered where fire performance is part of the specification, without moving away from the overall design intent.

All treatments are carried out in controlled conditions to ensure consistent application and reliable performance across the boards. This allows the fire-rated solution to remain aligned with the chosen texture, profile and finish, rather than introducing a separate material.

We work with project teams to select the appropriate system based on the required classification, façade build-up and desired appearance, ensuring the fire strategy integrates cleanly with the overall design.