NTR is a system for classification, approval, and quality control of treated wood.
Classification (NTR Document 1)
The classification system helps the end-user choose the right wood for the right purpose. The NTR classes are in line with the European standardisation system and its different use classes, in accordance with the European classification code. In practice, the NTR classes are the ones known to the trade and end-users on the market.
Read more about NTR wood protection classes and their uses here
Approval (NTR Document 2)
The approval system is managed by an independent technical group consisting of experts from the Nordic technical institutes. NTR document 2 defines the approval requirements of the protection product and is aligned with the European Biocidal Product Regulatory. Approvals are based on thorough documentation of durability in laboratory tests as well as field trials.
Read more about currently approved wood preservatives and systems here
Quality control: Internal and third party (NTR Document 3)
The quality control system (functions as a third-party control system run by independent control bodies located in all of the Nordic countries. They carry out controls at the production site that are based on the quality system and the specific product quality.
See all given certifications and the wood producers that have earned the right to mark their products with the NTR mark here