BS5837 categories help the design team and planning authority understand the relative quality and contribution of surveyed trees. They should always be read alongside the survey notes, remaining contribution, plan and development context.
A category is useful shorthand, but it is not a verdict. Development decisions still need a site-specific Arboricultural Impact Assessments and, where relevant, statutory protection checks.
Category A: high quality
Category A trees are those assessed as high quality with a substantial remaining contribution. Their value may be mainly arboricultural, landscape, cultural or conservation-related. They are likely to be important design constraints.
High category does not itself create a TPO, but proposals to remove or seriously affect such trees will normally require careful planning justification.
Category B: moderate quality
Category B trees have moderate quality or value and can still make an important contribution to a site. Many good urban trees fall into this category. Treating them as expendable merely because they are not Category A misunderstands the system.
The design should consider whether they can be retained successfully and how future growth will interact with the completed development.
Category C: low quality or limited contribution
Category C can include trees of lower quality, limited future contribution or small young trees that could be readily replaced. The category does not automatically mean the tree should be removed.
Planning authorities may still consider canopy cover, visual character, ecology and replacement planting.
Category U: unsuitable for long-term retention in the current context
Category U identifies trees whose condition means they cannot realistically be retained as living trees for the longer term in the context of the site. The survey should explain the reason.
Ecological considerations can still remain relevant. Deadwood, cavities and veteran features can support protected species or valuable habitat.
Categories inform design; they do not replace judgement
A proper impact assessment also considers Root Protection Areas, crowns, shading, future growth, removals, pruning, access and construction. The category starts the conversation; it does not finish it.
Practical Next Step
If an architect is working from a survey plan, ask that categories, crowns and Root Protection Areas are considered together. Arbor Cultural can take the information from BS5837 tree surveys survey stage into design assessment.
Relevant Arbor Cultural Services
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Frequently Asked Questions
Clear answers to common questions related to this subject.
Does a Category C tree have to be removed?
No. Category C does not require removal.
Can a Category A tree ever be removed?
Planning decisions are site-specific. A high-quality tree will normally require strong justification if removal is proposed, but the category is not an absolute legal prohibition.
Is Category U the same as dangerous?
No. Category U is a BS5837 retention category. Tree-risk assessment is a separate question.
Arbor Cultural Service Coverage
Arbor Cultural provides BS5837 Tree Surveys and related arboricultural consultancy across London and mainland South East England.
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Coverage includes the City of London and all 32 London boroughs, with project work across Central, North, East, South and West London.
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Homeowners, architects, developers, engineers, landowners, property professionals, insurers and organisations requiring independent arboricultural evidence.
For project-specific advice, you can contact Arbor Cultural or send your drawings and requirements through our online quotation form.
