Standard
EN 351-1 — Penetration and retention classes for preservative-treated timber
Clause 5 / Annex A. Defines penetration classes NP1–NP6 and requires declared retention for the intended use class. UC3 above-ground cladding typically requires NP2–NP3; UC4 ground contact requires NP5–NP6 with full sapwood penetration. Treatment declared without a penetration class and retention value is not verifiable.
The diagram below shows every direct connection this node has in the graph. Each line is one edge; expand a neighbour group below to read exactly why that connection exists and which standard or dataset it comes from.
Treatment (1)
- Preservative impregnation← specified under
Classification and declaration requirements for this treatment sit in EN351-TREAT.
Source: en351-treat
How edges in this graph are derivedWI-GRAPH v1.0.0
Species → agent edges come from the WI-SL resistance profile (0–100 ordinal scale derived from EN 350 durability class, extractive chemistry and movement). ≥70 is read as "resists well", 45–69 as "moderately resists", below 45 as "is vulnerable to".
Climate → agent edges fire when a climate's driver value (UV, humidity, salt or freeze-thaw load) is 60 or above, read directly from the climate dataset.
Treatment → agent / standard edges come from the paraphrased standards corpus used across the site (EN 927-1, EN 351-1, EN 350 clause 4, EN 13501-1).
Species → standard edges reuse the exact source list already published for each Global WoodIntel Score sub-score.
Machine-readable: GET /api/public/v1/graph?node=standard-en351-treat · CC BY 4.0