BS 5837 tree categories A, B, C and U explained

The surveyor gives each tree one category. The category shows the quality of the tree and how long it can stay as a living tree.^{2 3}

BS 5837:2012 has four categories only: A, B, C and U. There is no category R.

Trees in categories A, B and C should be considered for retention.⁴ BS 5837 starts from the position that there should be no structures inside the RPA of a retained tree.⁴

Categories A, B and C can each have one or more sub-categories. They show where the value of the tree comes from.³

• 1: mainly arboricultural values.
• 2: mainly landscape values.
• 3: mainly cultural values, including conservation.

So B2 is a tree of moderate quality whose value is mainly in the landscape. BS 5837:2012 gives each sub-category equal weight.³ Category U has no sub-categories.

BS 5837:2012 has a colour key for the categories.³ Published plans use green for A, blue for B, grey for C and dark red for U.² Councils ask for the BS colours on plans.⁴

Tree Atlas uses its own shades of these four colours. They follow the same green, blue, grey and dark red pattern. They are Tree Atlas design colours, picked to stay readable on white, and are not values taken from the standard.

Tree Atlas also prints the letter on every label, such as A·T1, so a plan still reads when it is printed in black and white.

Tree Atlas proposes a category from fixed rules. You make the final choice. The rules read the overall condition, the stem diameter and the protection choices: Veteran, TPO and Conservation Area.

• The rule version bs5837-v1.0 is stamped on every tree and every report.
• Every report has Appendix A · Method, which sets out the category rules and the rule version.
• The category is never suggested by AI. It comes from the rules and your confirmed fields.
• To change the category, tap A, B, C or U on the Assessment tab. Your choice is saved, and Tree Atlas keeps the proposal with the tree for audit.
• When you pick a letter yourself, Tree Atlas saves the middle sub-category: A2, B2 or C2. The tree record also has a sub-category field where you pick all that apply: 1 Arboricultural, 2 Landscape, 3 Cultural.

Read how categories are proposed and overridden in the help centre. Tree Atlas does not give professional advice. The category is your judgement as the surveyor.

Tree Atlas proposes the category as you record each tree, works out the root protection area, and prints both on the report, the Tree Constraints Plan and the DXF.