Better fire retardant wood products with new methods

Strong demand for high fire performance wood products


The fire performance of wood can be significantly improved with different chemical and physical methods without any disadvantages to the appearance of the wood or its usage qualities. VTT Technical Research Centre of Finland, together with the forest industry has developed more efficient fire retarding methods for different wood products. A number of different fire retarding methods for wood were discovered during a two-year international research project. In addition, more efficient evaluation methods were created to support the development of fire retardant wood products.

Applicable e.g. in public premises

”Fire retardant wood is suitable for internal and external surfaces of public premises, such as schools, theatres and shopping centres; for all such high risk locations with people or significant property values inside. Nearly non-combustible wood can be used as the surface material for emergency exits, in which case the appearance of the product does not differ from regular wood products,” says Esko Mikkola, Senior Research Scientist at VTT.

Fire retardant wood does not produce so much heat that it would contribute to the spread of fire. And it is not easily ignitable. The product may, however, become flammable if it is wrongly coated with, for instance, the wrong type of varnish or paint.

The use of different phosphorous-based compounds in fire retardant wood products was among the issues studied during the project. In the Nano-Silika method, very small particles of non-combustible substance are added to the wood product. The substance is used to have an influence on the formation of char, hence the fire performance. Another issue studied during the project was how fire retardant substances can be made to adhere to the cell structure of wood so that they will not move due to moisture.

Fire retardant plywood suits for wet spaces too

One of the key results of the project was a new type of plywood developed by VTT and UPM in cooperation; a thin layer of aluminium foil is added under the wood surface. As a result of the method, the fire performance of the product improved significantly but the appearance and workability of plywood were maintained. The product is suitable for very demanding applications, such as exterior walls and wet spaces, because the aluminium foil works as a vapour barrier preventing moisture from passing through the product.

Regulations increase demand

”It seems that there is a clear demand for products with improved fire performance. A majority of these products are exported outside Finland, where regulations are tighter,” says Simo Koponen, Research Manager at UPM.

The demand for fire retardant wood products is estimated to grow substantially in the near future. They can be used in many ways, particularly in the building and shipping industry and transportation. The methods charted in the project are now freely available and utilisable for all.

In addition to VTT, the Swedish research centre SP Trätek and the Stockholm Royal Institute of Technology KTH were involved in the project. Representing the forest industry UPM, Finnforest, Stora Enso, PressoCenter and Wood Focus from Finland and Borealis, Ingarps Träskydd, Wacker-Chemie and WPT from Sweden took part in the project. The project was part of the Finnish-Swedish Wood Material Science research programme. Tekes and VINNOVA provided funding for the project.


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