Burnblock® Fire Retardant Timber Treatment from Silva

Wood cladding from Silva can be treated with Burnblock® - a non-toxic fire-retardant system - up to Euroclass B- s1, d0 as classified under EN13501-1 and in accordance with EN14915. Burnblock® is leach resistant and is certified for use in INT1 (internal dry), INT2 (internal humid) or EXT (exterior) conditions.

Burnblock® treated timber comes with a certification of treatment and relevant CE marking declaring its performance characteristics as required by the Construction Products Regulation Act of 2013.

In most species of wood, Burnblock® causes little or no change to the appearance, but white surface salts may form under damp or humid conditions. These salts will weather off naturally once the cladding is in situ externally or can be removed with a brush or cloth.

+ Sustainability

Natural Fire-Retardant Solutions for Wood

Cradle to Cradle Certified®

Burnblock® Fire Retardant Powder is Cradle to Cradle Certified® at the Gold level.

BURNBLOCK is the first fire retardant in the Cradle-to-Cradle Certified® Products Program. Part of the sustainability certification includes a Platinum status for Material Health – the highest level of accreditation possible.

Burnblock - a sustainable choice for fire protection

  • Cradle to Cradle Certified™ at the Gold level
  • Natural
  • Non-Toxic
  • Biodegradable
  • Sustainable
  • No ingredients you will not commonly find in food or the human body
  • Easy soluble in water
  • PH neutral
  • Does not induce corrosion
  • Extremely low VOC (smoke toxicity)
  • Certified to highest European standards


The ingredients in Burnblock are found naturally in fruits, vegetables, or their elemental forms in nature.


Burnblock degrades 100% naturally with no adverse environmental effects.

Products using Burnblock can enter the circular economy.

Burnblock´s biodegradability was tested according to OECD Guidelines for the testing of chemicals (Method 310).


None (0%) of the substances in Burnblock are on the list of Substances of Very High Concern – SVHC.


Neutral ph value of 7.2.

+ Burnblock - Making Timber Fire Resistant

Burnblock fire retardant can be impregnated into various wood species using high-pressure treatment technology. This process is carried out in a dedicated facility within a controlled factory environment. The clear treatment doesn't leave any visible stains or imperfections other than surface salts that easily wash off.

A specialist kiln drying facility allows the timber to be returned to an appropriate or specified moisture level post-treatment, supporting construction standards to hold 10–18% moisture.

Why does Silva use Burnblock?

Silva uses Burnblock as standard in our fire-retardant treatment process as we want our customers to benefit from the most effective and environmentally friendly fire-retardant treatment available.

This entirely natural treatment is a UK-first for fire retardants, as many of the most popular and alternative treatments contain harmful or toxic chemicals currently under review. Burnblock is a 100% natural and non-toxic solution that’s fully biodegradable and easy to work with. It isn’t classed as a hazardous waste material, leading to considerable cost savings if you ever need to dispose of timber treated with it.

Burnblock is a water-based treatment made using components found in either fruits, vegetables, or nature in their elemental form and doesn’t cause any adverse effects on the environment.

BURNBLOCK has been thoroughly tested and certified to the highest European fire ratings by the most recognised institutes on the continent, including RI.SE (SP-fire) in Sweden, MPA in Germany, and BRE in the UK. Having been independently tested, Burnblock has proven and substantiated environmental credentials.

Performance certificates

Although BURNBLOCK is 100% natural and biodegradable, once impregnated, it will last the lifespan of the wood.  Its longevity is a result of the pressure impregnation process. BURNBLOCK will also achieve the same fire classification throughout the life of the timber.

Silva provides a Declaration of Performance per our CE Mark certification for fire retardant-treated timber. A legally required audit for factory production control of the fire-retardant facility ensures the consistency of performance of the manufactured products.

+ How Burnblock Works

How does Burnblock work?

Burnblock effectively prevents oxygen from reaching the treated object – and without oxygen: no fire.

Burnblock is a highly effective and well-documented fire retardant that can be used both industrially and as a post-treatment. It is an invisible treatment that, when applied correctly, leaves no greasing, so staining, no trace except for easily removable salt traces on the surface of the wood.

Once absorbed by the treated material, Burnblock leaves behind a surface that can char and release water in the event of a fire. During this process, the wood absorbs a portion of the heat and helps prevent further occurrence and spread of fire.

Therefore, wood treated with Burnblock is protected from combustion and any flame spread.

Burnblock Meets Regulatory Requirements

Burnblock has tested and classified a long list of wood species to the highest possible standard; EN13501-1:2007 (reaction to fire), EN14135 (resistance to fire), EN45545:2015 R1&R10 (rolling stock).

For pressurized fire extinguishers, Burnblock is certified for 55A, 40F, and 183B (with a foam additive).

What Health Risks Does Burnblock Represent?

Burnblock requires no specific safety equipment. However, some data indicate a slight irritation if Burnblock should accidentally come into direct contact with the eye. The Danish Technological Institute assesses this effect as less than natural lemons and fruit juice.

The Health Assessment from the Danish Technological Institute lists no significant health risks due to Burnblock components.


Burnblock does not induce corrosion.

Certificates and Documents

Burnblock has been thoroughly tested and documented by some of the best-ranking institutes in Europe.

+ How to Order Burnblock Fire Retardant Treated Timber

Please contact our team at 0151 495 3111 or enquiries@silvatimber.co.uk to discuss your fire-retardant-treated timber requirement.

What fire retardant-treated timber products can Silva supply?

We can supply the following products with Burnblock fire retardant treatment.

Western Red Cedar cladding and components – all grades

ThermoWood Pine cladding and components

Fraké Noir cladding and components

What is the lead time?

The current lead time is approximately 8-10 weeks.

Fire-retardant-treated timber cladding from stock

From August 2023, Silva will offer a limited range of fire-retardant-treated ThermoWood Pine cladding and components from stock. Please get in touch with us if you are interested in ordering any of this stock.


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