Reading a BS 5837 tree schedule column by column
The table at the back of an arboricultural report drives the planning decision. What each column means, and how to use stem diameter to test your own layout.
A BS 5837 tree schedule is the table at the back of your arboricultural report, and every column in it feeds a decision the case officer will make. Reading it takes about ten minutes once you know what each heading means. The two columns that matter most to a householder are the category grading, which tells you how hard the council will fight to keep the tree, and the stem diameter, which sets the root protection area your extension has to stay out of.
The schedule is produced to BS 5837:2012, the British Standard on trees in relation to design, demolition and construction. Surveyors follow its structure closely, so schedules from different consultants look much the same.
Tree number, species and how they tie to the plan
The first column is a reference number, usually T1, T2 and so on for individual trees, G1 for groups, H1 for hedges and W1 for woodland. Those references appear on the tree constraints plan and, later, on the tree protection plan.
Check they agree. A schedule that lists eleven trees against a plan showing nine is the commonest reason a tree report gets sent back, and it is almost always a drawing revision that was never reissued.
Species is given by botanical name, sometimes with the common name alongside. It matters more than it looks. Species drives likely rooting habit, water demand in shrinkable clay, expected lifespan and whether the tree is worth retaining at all in that position.
Height, stem diameter and crown spread
Height is in metres, measured or estimated. It is the least useful figure in the table for planning purposes, though it matters for shading and for the 25 degree daylight checks a neighbour might raise.
Stem diameter is the one to read carefully. It is recorded in millimetres and measured at 1.5m above ground level, which arborists call diameter at breast height. Where a tree forks below that point, or leans, or stands on a slope, the standard sets out how to take the measurement, and multi-stemmed trees are recorded stem by stem.
The reason it matters is arithmetic. The root protection area under BS 5837:2012 is calculated as an area equivalent to a circle with a radius of twelve times the stem diameter for a single stemmed tree, capped at 707 m². A 400mm stem therefore generates a 4.8m radius. Your foundations, your scaffold and your site compound all have to respect it, or the design has to show how the roots are protected.
Crown spread is given as four figures, one for each compass point, in metres from the centre of the stem. An asymmetric crown shows up here as a wide figure in one direction and a narrow one in another, which usually reflects past pruning or competition rather than root distribution.
Crown clearance is the height of the lowest branches above ground, and it tells you how much headroom exists before pruning becomes necessary for access.
Age class, condition and remaining contribution
Age class runs young, middle-aged, mature, over-mature and veteran. Veteran status is a planning issue in its own right, because national policy treats ancient and veteran trees as irreplaceable habitat with a high bar for loss.
Condition is split into physiological and structural. Physiological covers vitality: crown density, dieback, leaf size and colour. Structural covers defects: cavities, included bark at forks, fungal fruiting bodies, root plate movement, previous failures. A tree can be in good physiological condition and poor structural condition, which is how an apparently healthy tree ends up as a category U.
Estimated remaining contribution is given in bands, commonly less than ten years, at least ten, at least twenty and at least forty years. It is a judgement about how long the tree will continue to contribute to its setting in its current context, not a prediction of biological lifespan.
The category grading and what it signals
This is the column officers read first.
| Category | What it means | Practical effect |
|---|---|---|
| U | Cannot realistically be retained as a living tree for more than ten years | Removal is rarely resisted, though replacement may still be sought |
| A | High quality with a remaining contribution of at least forty years | Loss is very hard to justify, and layouts are expected to work around it |
| B | Moderate quality with at least twenty years | Retention is the starting point, and loss needs a clear justification |
| C | Low quality with at least ten years, or young trees below 150mm stem diameter | Loss is often acceptable where mitigation is offered |
Each category carries a subcategory number: 1 for mainly arboricultural value, 2 for mainly landscape value, 3 for mainly cultural or conservation value. A tree graded B2 is being retained mostly for what it does in the street scene, which changes the argument about whether a replacement elsewhere on the plot would do.
Category alone is not the whole picture. A category C tree with a Tree Preservation Order on it is still protected by the order, and a category C tree in a conservation area still needs six weeks' notice before works.
Preliminary management recommendations
This column lists work the surveyor considers necessary regardless of the development: deadwood removal, crown lifting over a footway, removal of a hazardous limb, or felling of a category U tree.
Read it as a cost line. If the schedule says a tree needs a crown reduction before the extension is built, that work has to happen, it needs consent where the tree is protected, and it needs a written specification rather than an instruction to a contractor to tidy it up. Getting the pruning specification written properly is the difference between work the council accepts and work that becomes an enforcement matter.
Recommendations in this column are not the same as the mitigation proposed for the development. Those belong in the arboricultural impact assessment and the method statement.
Using the schedule to test your own design
Take the stem diameters for the trees nearest your proposed footprint, multiply each by twelve, and draw those radii on your block plan. That is a rough version of what the tree constraints plan does, and it tells you in five minutes whether the scheme has a problem.
Where a foundation falls inside a root protection area, the options are to move the building, to reduce the footprint, or to design a foundation that avoids excavation in the rooting zone. Those are real engineering choices with real costs, and they cost far less when made before the drawings are finished.
Where the scheme is tight, expect the council to condition tree protection fencing, a construction exclusion zone and supervision by the arboriculturist. Keeping a mature tree alive through a construction programme depends more on what happens on site than on what the report says.
And if a neighbour's tree is the constraint, note that the schedule may cover it without you having any control over it. Its roots and canopy are still a constraint on your design, and separate questions arise where a tree is implicated in subsidence at a neighbouring property.
What to check before the report is submitted
Three checks catch most problems. Do the tree numbers in the schedule match the plan and the report text? Are the stem diameters recorded for every tree whose root protection area touches the proposed works, including trees on adjoining land? Does the category grading in the schedule match the grading shown on the constraints plan?
Then read the survey date. Councils treat tree surveys as reasonably durable, but a survey more than two years old will attract a request to update it, particularly where a storm has passed through in the meantime.
A tree survey and arboricultural impact assessment is a local validation requirement in most authorities wherever trees are close to the works, so getting the schedule right is not optional detail.
Enter your postcode on PlanScope to see which supporting documents your project is likely to need.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
What do tree categories A, B, C and U mean?
U covers trees that cannot realistically be retained as living trees for more than ten years. A is high quality with a remaining contribution of at least forty years, B moderate quality with at least twenty, and C low quality with at least ten, or young trees below 150mm stem diameter. Each carries a subcategory for arboricultural, landscape or cultural value.
How is the root protection area calculated?
For a single stemmed tree, BS 5837:2012 sets an area equivalent to a circle with a radius of twelve times the stem diameter, capped at 707 square metres. Multi-stemmed trees use a different derivation. A 400mm stem gives roughly a 4.8 metre radius, which is usually enough to catch a nearby extension footprint.
Where is stem diameter measured on a tree survey?
At 1.5 metres above ground level, recorded in millimetres, which arborists call diameter at breast height. The standard sets out adjustments where the tree forks below that height, leans, or stands on sloping ground. Multi-stemmed trees are recorded stem by stem rather than as a single figure.
Can a category C tree be removed without consent?
Not automatically. The category reflects quality, not legal protection. A category C tree covered by a Tree Preservation Order still needs consent, and one in a conservation area still needs six weeks' written notice. Councils also frequently ask for replacement planting even where the loss of a low quality tree is acceptable in principle.
How old can a tree survey be before a council rejects it?
There is no fixed rule, but surveys more than about two years old commonly attract a request to update. Condition changes, storms cause damage, and category gradings move. If the survey predates significant weather events or visible decline, expect the case officer to ask for a revisit before validation or before conditions are discharged.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.