Is Shou Sugi Ban Fire Resistant? What Testing Means

Timber is combustible, and charring alone does not give a facade a fire classification, whatever surface style is specified. Where a project needs one, Degmeda supplies certified B-s1, d0 products: Deep Char spruce and Deep Char larch in a shiplap profile. Ask us for the certificate covering your exact product, thickness and build-up. The certified products are impregnated with a fire-retardant treatment as part of how the class is achieved — the B-s1, d0 page sets out exactly what the certificate covers.

Where a project has regulated fire requirements, check that the classification documentation covers the product specified.

Reaction to Fire and Fire Resistance Are Different

These terms are often confused:

• Reaction to fire describes how a material contributes to ignition, flame spread, heat release, smoke and related behaviour during the early stages of a fire.
• Fire resistance describes how a complete building element, such as a wall, floor or door assembly, maintains functions such as loadbearing capacity, integrity or insulation for a stated period.

A cladding board may have a reaction-to-fire classification, but that does not mean the façade wall has a fire-resistance rating. The second question requires evidence for the complete assembly.

How the Existing Char Layer Affects Fire Behaviour

Large structural timber elements can form a char layer during a fire, and fire engineers account for that behaviour through appropriate calculations and testing. A decorative carbonised surface created during manufacturing is assessed as part of the finished cladding product.

The pre-charred layer may be retained, brushed or coated, and each configuration can influence the behaviour of the complete board under fire exposure. Recognised testing and classification capture these product-specific differences.

Timber chemistry, board dimensions, finishing and the surrounding construction all contribute to fire performance, so documented evidence provides the reliable basis for specification.

How Degmeda Controls the Burning Process

Degmeda uses a controlled production process with dedicated furnaces. Species, natural grain, brushing, coating and other finishing choices create the product appearance.

Controlled production supports consistency, while fire classification is established for each tested product.

What Determines the Fire Classification?

Relevant variables can include:

• timber species, density and board thickness;
• profile, joints and orientation;
• Deep Char or brushed surface;
• coating, pigment, oil or fire-retardant treatment;
• fixings and support arrangement;
• the substrate class recorded on the certificate;
• whether the product carries the fire-retardant treatment;
• interior or exterior use and the applicable test standard.

The classification applies to the product as tested and recorded on the certificate. Supporting evidence can confirm when a result covers another species, profile or Degmeda product.

Can Charred Timber Receive Fire-Retardant Treatment?

Some timber systems can use a compatible fire-retardant treatment or coating to achieve a required classification. Including that treatment within the assessed product build-up connects the installed system to the documented result.

The approved combination also considers colour, surface texture, coating adhesion, moisture behaviour and maintenance. The manufacturer, supplier and fire consultant can confirm the suitable system before production or installation.

What Evidence Should a Designer Request?

For a regulated project, request current documentation that identifies:

• the exact product and species covered;
• the test or classification standard;
• the declared reaction-to-fire class or other result;
• board dimensions, orientation and joint details;
• coating and any impregnation or treatment;
• substrate, cavity and fixing conditions;
• field of application and stated limitations;
• the validity and issuing body of the document.

Degmeda holds documentation for specific charred timber build-ups. Matching that evidence to the project specification allows the relevant performance to be communicated accurately.

Applying Fire Classification in Different Markets

Building regulations, accepted standards and required performance vary by country, building type, height, occupancy and location on the façade. Local authorities or insurers may also have additional conditions.

The project architect, fire engineer or other responsible professional can determine the requirement and confirm that the proposed evidence is accepted in the relevant jurisdiction.

Can Coating or Maintenance Change the Evidence?

Yes. Adding, replacing or renewing a coating can change the assessed product build-up. Before applying a different oil, stain, sealant or fire-retardant finish, confirm whether the classification remains applicable.

This is especially important when maintaining factory-finished boards. A product that looks visually similar may have different composition and fire behaviour. Keep the original order and finish records for future maintenance.

What Fire Classification Confirms

A classification describes performance under defined test conditions and establishes how the assessed product contributes within a compliant design. It works together with cavity barriers, fire stopping, alarms, sprinklers and any other measures required by the project.

This allows designers to select a charred timber product with documented fire behaviour while coordinating moisture management, exposure, product choice and the complete building detail separately.

Installation Matters

Correct installation preserves the documented performance. Cavity depth, barriers, membranes, fixings and board orientation are set by the building’s fire strategy, and should follow the design the fire professional has approved.

Providing installers with the relevant details before work begins, reviewing substitutions and keeping site records or photographs helps demonstrate that the specified assembly was followed.

Is Shou Sugi Ban Fire Resistant? The Practical Answer

Degmeda charred wood products with supporting fire-performance documentation can be specified according to the exact assessed combination. The product name, profile and installation details should match that evidence.

Send Degmeda the intended country, application, product, profile and required classification before ordering. We can then identify available documentation for the proposed specification. Explore our charred wood products or read the guide to compatible coatings and maintenance.