Fire Retardant Wood Cladding: Lunawood ThermoWood® in Fire Class B

Wood is widely used in modern architecture, but many projects require Fire Class B fire classification for cladding materials. Fire retardant Lunawood ThermoWood® offers a durable and maintenance-free wood cladding solution while maintaining the natural appearance and durability of thermally modified wood.

Although most commonly used in facade cladding, Fire Retardant Lunawood ThermoWood® can also be specified for interior wall and ceiling applications where improved fire resistance is required.

The fire-retardant treatment used for Lunawood penetrates deep into the wood structure, providing durable fire protection without additional maintenance coatings.

What is Fire Retardant Lunawood ThermoWood®?

Fire retardant Lunawood ThermoWood® is thermally modified Nordic pine or spruce treated with a sustainable fire-retardant solution that improves the wood’s fire resistance.

The treatment enables Lunawood products to achieve Fire Class B fire classification according to EN 13501, allowing natural wood cladding to be used in projects where untreated timber would not meet fire safety requirements.

Because the treatment penetrates the wood structure, the fire protection remains consistent throughout the board and throughout the product’s lifecycle.

Why Choose Fire Retardant Lunawood ThermoWood®?

• Fire protection throughout the wood structure
  • No maintenance repainting required
  • Cut ends do not require additional treatment on site
• The wood naturally greys like standard Lunawood ThermoWood®
• Suitable for projects requiring Fire Class B fire classification

Fire retardant Lunawood ThermoWood® is a practical solution that is easy to work with on the building site and provides low maintenance in the long term.

The treatment process is fully documented and CE-certified and uses an environmentally friendly non-toxic agent that does not evaporate or form harmful compounds, making the material safe for both exterior and interior applications.

What Does Fire Class B (B-s1,d0 / B-s2,d0) Mean?

The European fire classification system EN 13501 describes how building materials behave during fire.

B
Limited contribution to fire.

s1 / s2
Smoke production level.

d0
No flaming droplets during fire.

Fire retardant Lunawood ThermoWood® cladding can achieve:

• B-s1,d0 – very limited smoke production
• B-s2,d0 – limited smoke production

Both classifications meet Fire Class B requirements commonly used for cladding materials in regulated construction projects.

Which Lunawood Profiles Achieve Fire Class B?

Flat tongue-and-groove products (spruce / pine)

Fire classification:
B-s1,d0

Dimensions:
15–42 × 42–192 mm

Examples include:

• Luna Panel System products
• Luna TGV profiles
• other flat tongue-and-groove cladding boards

These profiles provide very limited smoke production during fire and are suitable for both interior and exterior applications.

3D tongue-and-groove products (spruce / pine)

Fire classification:
B-s2,d0

Dimensions:
26–42 × 42–192 mm
(as well as various thicknesses of Luna Panel System products)

These profiles include deeper shadow gaps and architectural shapes and are suitable for both exterior and interior use.

Fire Retardant Lunawood Claddings Available from Stock

Some fire retardant Lunawood Collection profiles are available directly from stock, making them suitable for projects with tight timelines.

Luna Panel System 19×140

• sharp edge profile
• end-matched boards
• narrow shadow gaps for a clean architectural appearance

Luna Triple HF 26×140 

• 3D-profile
• hidden fixing groove
• screw-free surface
• adds depth and rhythm to the facade
• clean, uninterrupted architectural appearance

Are Other Lunawood Products Available Fire Retardant?

Yes. Lunawood’s fire-retardant treatment is available for most tongue-and-groove cladding products in the Lunawood Collection.

Products can be supplied:

• fire retardant treated
• fire retardant treated and factory painted in various colour tones

Typical delivery times:

• Fire retardant treated products: 6–10 weeks
• Fire retardant treated and painted products: 9–13 weeks

Practical Benefits of Fire Retardant Lunawood ThermoWood®

Many fire-rated timber solutions rely on surface-applied fire-retardant coatings, which typically require maintenance repainting during the building lifecycle.

Cut ends often also need to be treated separately on site, which increases installation time and cost.

Fire retardant Lunawood ThermoWood® works differently because the treatment penetrates the wood structure.

This means:

• no repainting required to maintain fire classification
• no additional treatment needed for cut ends
• consistent fire protection throughout the board
• natural weathering similar to untreated Lunawood ThermoWood®

Over time, the wood develops the familiar silver-grey patina caused by UV exposure and rain.

Planning a project requiring Euroclass B wood cladding?
Our team can help you select the right Lunawood ThermoWood® profile and fire classification for your project.