The main species used in the Nordic countries is Scots Pine, due to its suitability for preservative treatment. Preservative treatments make it possible to use Scots Pine in outdoor applications, which ensures local jobs and short transportation. Other species such as Norway Spruce are used, but Norway Spruce is not permeable so a special treatment and classification is included in the NTR system.
Durability of NTR marked wood
The NTR system certifies that the wood has a long service life.
Above ground durability (NTR class AB) is prolonged dramatically – by up to 50 years or more depending on the application; for example, decking is more exposed to weathering than cladding. This means that the service life is increased five to ten times more than untreated wood.
In ground contact such as wooden poles (NTR class A) the service life is also five to ten times longer than untreated wood.
NTR requires field trials for performance documentation, which is unique in Europe, and ensures that any new product meets expectations.
The environmental impact of treated wood is highly regulated. The work and external environment of the production sites are audited and approved by the authorities. The use of biocides are approved by the European Chemicals Agency, according to the Biocidal Products Regulation (BPR). At a national level, the preservative product is approved based on efficacy and environmental data. All NTR products are approved according to BPR.
Wood treatment prolongs the service life of wood products, reducing their replacement rate and leading to more resource efficient use of the forests. Timber used for NTR treatment is often from sustainable forests (PEFC or FSC) but is not part of the scope of the NTR system. To specify forest certification could improve sustainability and ensures that the forest is cultivated in a sustainable way. Since wood is a renewable material and absorbs CO2 when growing – it contributes to meeting United Nations Sustainable Development Goals 12 (responsible production and use) and 13 (climate effort).
The treatment process is typically carried out in a closed pressure vessel where the preservative penetrates the sapwood structure. NTR audits the production site twice a year, which is a unique standard.