Glossary — UK Planning
BS5837 Categories
A / B / C / U grading
BS5837:2012, the UK standard for trees in relation to design, demolition, and construction, grades every surveyed tree A, B, C, or U. The letter is a shorthand for how strongly the tree should influence a site layout — A trees drive the design around them, U trees should come out regardless of the development.
The four categories
Category A — high quality, best examples of their type, or particularly good specimens with a long safe useful life expectancy. Retain and design the site around them.
Category B — moderate quality, reasonable retention value. Worth retaining if it's reasonably practicable given the wider design, but not a hard constraint on layout the way an A tree is.
Category C — low quality, limited retention value. Keep only if it's convenient — a C tree in the way of a sensible layout is fair game to remove.
Category U — unsuitable for retention. Dead, dying, structurally unsound, or with a life expectancy under about ten years. Remove irrespective of development — a U tree isn't being weighed against the site plan, it's coming out either way.
Subcategories: 1, 2, 3 — the reason for the grade
A and B (and sometimes C) trees also get a subcategory that records why they earned that grade: 1 for arboricultural quality (the tree itself — form, vigor, structural condition), 2 for landscape value (screening, visual amenity, contribution to townscape or setting), and 3 for cultural or conservation value (veteran status, historic or commemorative significance, wildlife habitat). A tree can carry more than one subcategory — a mediocre specimen that happens to screen a busy road might be a B2 even though it's not a B1 on form alone.
Why the grade matters for the site plan
The category feeds directly into the Tree Constraints Plan and the Arboricultural Impact Assessment a planning authority reviews. A validation officer checking a submission expects to see categories assigned consistently with BS5837's criteria, not a rating that reads like a vague quality opinion — this is one of the more common reasons a survey gets kicked back at validation.
Related terms
Recording categories in a survey
See the BS5837 tree survey guide for the full process, or LogLog's preservation category field — A/B/C/U is a built-in field on every tree record, alongside a separate heritage flag for veteran or notable trees.
Assign the category at the tree, on the plan, while the reasoning is still in your head. LogLog carries it straight through to the export.
Get early access Open the app