Here you will find information on fire protection of wood products. We answer frequently asked questions about fire protection requirements for wood construction products, NT DECO flame retardant and how it can be used.

Nordtreat FAQ

Find questions and answers by topic categories:

1. Fire protection requirements and certification

What does B-s1, d0 mean?

Reaction to Fire classification (Euroclass) B-s1, d0 means that the treated wood products contribute to the fire to a very limited extent, their smoke production is very limited and no flaming droplets occur. The different Classes for building materials are A1, A2, B, C, D, E and F. Smoke production and the formation of flaming droplets are expressed with the additional smoke production classes s1, s2 and s3, and formation of flaming droplet classes d0, d1 and d2.


What is an M1 certificate?

M1 refers to an emission classification system of building materials developed by the Building Information Foundation RTS in Finland. The construction products are divided into classes M1-M3, of which M1 is the best, indicating low emissions. Nordtreat’s NT DECO meets emission standards of class M1, as well as the following indoor air quality standards: Indoor Air Comfort®, CDPH, A+, AgBB, BREEAM and LEED v4.


What wood species do Nordtreat’s certificates cover?

Following the certificates from accredited laboratories and testing institutes, Nordtreat’s NT DECO fire retardant can be used on Spruce, Larch and Western Red Cedar.

2. Features and benefits of NT DECO flame retardant

What are Nordtreat‘s NT DECO‘s key benefits?

Nordtreat’s NT DECO is the only environmentally friendly, non-harmful, water-based, one-pot solution flame retardant treatment for the wood industry that can be used in interior and exterior conditions and that is available in thousands of semi-translucent colours. NT DECO is safe and easy to handle and apply. It enables the use of many wood products in fire critical environments, with proven reaction to fire performance.

What are the differences between NT DECO and other flame retardant systems?

Nordtreat’s NT DECO is a waterborne, ecological and harmless flame retardant, free of halogenic components. It is an ideal product for sustainable wood construction.

How durable is NT DECO in outside use?

Nordtreat’s NT DECO is a translucent wood stain that has been designed to work in outside use for the flame retardant treatment of cladding for example. In this environment, the NT DECO treated surface, when treated according to Nordtreat guidance, keeps its flame retardant properties and withstands direct weathering for a minimum of 5 (five) years. The suitability of NT DECO for outside use has been confirmed in several tests and proven by the standard EN 16755 “Durability of reaction to fire performance” with the class EXT.


Does NT DECO offer any biological protection to the wood? Against UV, fungus/mould, insects?

Nordtreat’s NT DECO protects wood surfaces against UV and the effects of sunlight.

Does NT DECO have the tendency of flaking or peeling off?

No, Nordtreat’s NT DECO is micro penetrating the wood surface and is not forming a traditional surface layer on top of the wood substrate. Therefore a peeling of or flaking is not possible.

Can NT DECO treated wood products be recycled?

Small amounts can be treated in normal wood waste. Bigger amounts should be treated according to local waste regulation.

Where and how is NT DECO produced?

NT DECO is produced in Nordtreat’s own factory in Porvoo Finland. The production is based on the latest chemistry and technology.

3. End-uses of NT DECO flame retardant

Can I use NT DECO for floors or stairsteps?

No, Nordtreat’s NT DECO is designed only for vertical wood surfaces that are not subject to wear and use (such as floorings or deckings). The classification of the reaction to fire performance of B-s1, d0 is only given for vertical use products.

Could I make NT DECO treatment on wood material that is on a vertical position outside?

Yes, but it must be ensured that Nordtreat’s NT DECO Technical Datasheet instructions are followed. In some cases, temporary weather shelter is needed.

Can I use NT DECO for joinery products such as doors and windows?

No, Nordtreat’s NT DECO is designed for non-dimensional timber products such as facade panels and construction timber products like CLT and glulam.

4. Application of NT DECO flame retardant

What is the best method to apply NT DECO?

Nordtreat’s NT DECO is suited for both industrial (brush-machine, vacuum-spray, flow-coater, Airmix spray) or manual (with a brush, spray) treatment. Always treat the wood surfaces according to the instructions given in NT DECO's Technical Datasheet.

Can I use a primer before I paint the wood with NT DECO?

No, Nordtreat’s NT DECO is designed to micro penetrate the wood surface. Applying NT DECO on a primer would lead to bad adhesion and will affect the reaction to fire performance.

How much NT DECO must I apply to achieve the fire class B-s1, d0?

To achieve the reaction to fire class of B-s1, d0 according to EN 13501 the approved wood species of spruce, larch and red cedar have to be treated with 350 g/m² on all accessible/visible surfaces, according to the manufacturers’ guidance.

What is the recommended drying time for NT DECO?

The intermediate drying time between layers should be 2 hours in ambient conditions or approx. 6-10 min in drying conditions of 55-65° C, depending on the type of wood, air temperature, humidity level, etc. Excessive (> 10 hours) drying between coats might result in poor impregnation of the adjacent coats. NT DECO is touch dry after 48 h at +20° C and average humidity of <65 %. The final surface is ready for use after 7-10 days at +20° C and average humidity of <65 %.

Can I apply a different product on top of the NT DECO flame retardant system?

NT DECO is not designed to be coated by lacquering or subsequent processing with film-forming coatings and such post-processing would affect the reaction to fire classification.

How can I make the NT DECO treatment when the installation is already done?

Nordtreat’s NT DECO treatment for facades should be applied for all four sides of the product in order to meet the demanded reaction to fire standard so it's not possible after the installation has been done. CLT can be treated onsite after installation.

What material screws and nails I should use with NT DECO treated wood?

Always use inoxidable stainless steel nails or screws.

Where can I buy NT DECO?

Nordtreat’s NT DECO is a technical paint product for professional use. It is not sold in markets for private use. If you are a professional wood treatment company or a painter or building company, please contact Nordtreat directly.


Where can I store NT DECO?

Nordtreat’s NT DECO is stored in normal storage where the temperature is 4-30 °C and where the product is kept away from direct sunlight.

5. Maintenance of NT DECO treated wood surfaces

What is the maintenance period in the NT DECO fire retardant system?

Surfaces in exterior conditions treated with Nordtreat’s NT DECO such as facade cladding will maintain its reaction to fire classification for at least five (5) years when fully exposed to weathering. After five (5) years treated surfaces should be inspected for maintenance needs.

What are the maintenance volumes of NT DECO?

Affected surfaces should be maintenance-treated by applying 175-350 g/m2 of NT DECO depending on the surface quality.

Why does NT DECO only have a five-year certificate for exterior application?

The performance of the flame retardant treatment with NT DECO has been tested in extensive weathering tests according to the different standards such as EN 927 and EN 16755. The durability of the performance of the flame retardant is subject not only to the persistence of the active fire retardant substances in NT DECO but also to the durability of the whole paint system. Outside weathering are severe conditions for painted wood products and these need maintenance. Nordtreat decided for the 5 years maintenance period to make sure that the treated surfaces stay protected and performant for a long time.

6. Sourcing of fire-protected wood products

Where can I buy wood products (claddings, logs, CLT materials) treated with NT DECO?

Contact Nordtreat. They provide a list of local partner companies that use Nordtreat’s NT DECO to offer high quality flame retardant wood products.



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