Wood IntelligenceResearch Institute

Research briefs

Short, citable reads for journalists and specifiers

Each brief summarises one durable-wood topic in plain language, cites the underlying standards and research, and links to the open data behind every claim. Download the PDFs or cite the web version.

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wi-brief-0012026-08-016 min read

Untreated vs surface-protected wood in Nordic climates

A concise comparison of service-life expectations for untreated and maintained wood in the Nordic climate zone. The brief explains why detailing often outweighs durability class, and how EN 335 use-class logic interacts with local climate load.

Key takeaways

  • Reference service lives from EN 350 durability classes are not climate-specific; the model converts them using ERA5-derived load terms.
  • In the Nordic zone, a ventilated cavity and sloped end-grain can add more modelled life than moving from durability class 4 to class 2.
  • Surface-protected systems only realise their gain if maintenance is actually carried out; the brief includes a maintenance-credit sensitivity table.
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Cite this page

Wood Intelligence. (2026). Untreated vs surface-protected wood in Nordic climates. Wood Intelligence. https://woodintel.io/briefs#untreated-vs-protected-nordic
woodintel.io/briefs#untreated-vs-protected-nordic

Sources

  • EN 350:2016 durability classification
  • EN 335:2013 use classes
  • ERA5 reanalysis climate drivers
  • WI-VAL v1.1.0 Nordic field cases
wi-brief-0022026-08-018 min read

Climate-zone effects on decay risk — model vs field trials

How the Wood Intelligence model translates Köppen climate classes into decay hazard, and how those model outputs compare with the 24-case WI-VAL benchmark. Includes leave-one-out accuracy and known failure modes.

Key takeaways

  • The model uses five climate drivers (UV, driving rain, humidity, chloride, freeze-thaw) normalised per Köppen zone.
  • Tropical (A) and arid (B) zones carry the highest calibration uncertainty because the benchmark contains fewer completed observations.
  • Leave-one-out validation shows a mean absolute error of 4.8 years and 83 % interval coverage after calibration.
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Cite this page

Wood Intelligence. (2026). Climate-zone effects on decay risk — model vs field trials. Wood Intelligence. https://woodintel.io/briefs#climate-zone-decay
woodintel.io/briefs#climate-zone-decay

Sources

  • WI-SL v1.2.0 method equations
  • WI-CAL v1.1.0 calibration factors
  • WI-VAL v1.1.0 24-case benchmark
  • ERA5 / Copernicus climate reanalysis
wi-brief-0032026-08-015 min read

How to read EN 335 and EN 16449 declarations

A specifier's guide to translating EN 335 use classes and EN 16449 performance declarations into real project decisions. The brief highlights common misreadings and links each concept to the Wood Intelligence calculation trace.

Key takeaways

  • EN 335 use class 3 covers above-ground exterior exposure, but does not by itself specify service life in years.
  • EN 16449 declarations report durability performance; they do not replace climate-specific design.
  • The gap between declaration and site life is where orientation, exposure, maintenance and species resistance profile matter.
Download PDF

Cite this page

Wood Intelligence. (2026). How to read EN 335 and EN 16449 declarations. Wood Intelligence. https://woodintel.io/briefs#reading-en-335-460
woodintel.io/briefs#reading-en-335-460

Sources

  • EN 335:2013
  • EN 16449:2014
  • EN 350:2016
  • Wood Intelligence method documentation