Read your arboricultural report in this order: find each tree's BS5837 category (A, B, C or U) and Root Protection Area in the schedule, check whether any tree is flagged as protected by a TPO or conservation area, then see on the drawings where your proposal clashes with a tree you are meant to keep — that clash is what determines your planning outcome.
You have been handed a document full of tables, abbreviations and coloured circles, and you need to know what it means for your project. This guide walks you through it the way a planning adviser would, whether you are a homeowner extending a house or a developer running a site — and it explains where the report stops being your call and becomes your council's, because tree-officer expectations vary by authority.
First, work out which report you are holding
An arboricultural report is a stack of related documents, and it matters which stage you are at:
| Document | What it records | Stage |
|---|---|---|
| Tree Survey + Tree Constraints Plan (TCP) | Every relevant tree, its category and RPA, and the space it occupies | Pre-design / pre-submission |
| Arboricultural Impact Assessment (AIA) | Your proposed layout tested against the trees | Submitted with the planning application |
| Tree Protection Plan (TPP) | Fencing, exclusion zones and protected routes | With the application, finalised at discharge |
| Arboricultural Method Statement (AMS) | The detailed "how we protect them" methodology | Often a pre-commencement condition, approved after permission |
If your council has asked for something "to validate the application", you almost certainly need the survey and AIA. A condition to discharge means you are into TPP/AMS territory. The rest is the full document stack.
Step 1: Read the tree schedule
The schedule is the big table, usually at the back. Each row is one tree, group ("G1") or hedge ("H1"). Focus on three columns.
The category column (A, B, C, U)
This is the single most important field. It is the BS5837:2012 retention grade, and it drives the whole negotiation with the tree officer:
| Category | Plain meaning | Est. remaining contribution | What it means for you |
|---|---|---|---|
| A | High quality, keep it | 40+ years | Very hard to justify removing; design around it |
| B | Moderate quality | 20+ years | Retention desirable; removal needs a good reason |
| C | Low quality, or young/small | 10+ years (or young stems) | Little constraint; easier to remove or work near |
| U | Unsuitable for retention | Under ~10 years | Dead, dying or dangerous — expected to be lost anyway |
A number after the letter (A1, B2, C3…) records why the tree has value: 1 = mainly arboricultural qualities, 2 = mainly landscape value, 3 = mainly cultural value including conservation. So "A1" is a high-quality tree valued for the tree itself; "B2" a moderate tree valued for its landscape contribution.
One important correction: if you see "Category R" anywhere, the report is using outdated 2005-edition or informal wording. In BS5837:2012 the correct code for a tree to be removed is U (unsuitable for retention). A report still using "R" is a small flag about how current its author is.
The practical rule: removing a C or U tree rarely troubles a tree officer; proposing to fell an A tree will almost always be the fight in your application.
The Root Protection Area (RPA)
Every tree has an RPA — the below-ground rooting zone that must be kept clear of digging, compaction and level changes. For a standard tree it is calculated as 12 × the stem diameter (measured at 1.5 m above ground), capped at 707 m² (a 15 m radius) for the largest trees. Veteran or ancient trees get a larger RPA — 15 × the stem diameter, or the canopy edge plus 5 m, whichever is greater — because they are treated as irreplaceable habitat. You do not need to do the maths; the report has. But you do need to see where the RPA lands on the drawings, because your foundations, driveway, drains and patio generally cannot intrude into it without an engineered solution. See the Root Protection Area guide for the detail.
Condition and remaining contribution
These tell you the surveyor's read on the tree's health and remaining life. A B-category tree with a remediable defect can sometimes be worked with; a genuinely declining tree may support your case for removal.
Step 2: Read the drawings
The Tree Constraints Plan (and the AIA plan) overlays the survey onto a scaled site drawing. Look for:
- Circles or polygons around each tree — those are the RPAs. A polygon means the surveyor judged the roots to be asymmetric (for instance constrained by an existing wall or road) and re-shaped the area while keeping the same total size.
- Crown spreads — the canopy outline, usually measured in four directions, relevant to shading and clearance.
- Colour coding — by convention A trees are shown green, B blue, C grey and U red, though house styles vary, so read the plan's own key rather than assuming.
Now put your proposed layout mentally over the top. Anywhere your building, hard surfacing or excavation lands inside the RPA of a tree you are keeping is a conflict — and conflicts are exactly what the AIA discusses and what the tree officer scrutinises.
A worked example
Say you are adding a rear extension near a neighbour's oak with a 600 mm stem diameter. Its RPA radius is 12 × 0.6 = 7.2 m — a circle of roughly 163 m² reaching across the boundary and over the corner of your proposed footprint. Being off-site and healthy, the oak is likely A or B category, so its RPA is a hard constraint you did not create and cannot remove. Your options are to pull the footprint back out of the RPA, or to justify the incursion with a special foundation or no-dig detail. That single overlap is the crux of the application.
Step 3: Look for the protected-tree flags
Scan the report for two phrases that change everything, because they trigger a separate, criminal-law regime that sits on top of planning:
- Tree Preservation Order (TPO) — you need the council's separate written consent to cut, prune or damage the tree, on top of any planning permission — a distinct application with an eight-week decision period. Doing the work without consent is a criminal offence carrying fines up to £20,000 in the Magistrates' Court for destroying a protected tree (unlimited in the Crown Court), plus a duty to plant a replacement. Check status on the TPO check page and read the TPO guide.
- Conservation Area — trees here are protected by a six-week notice regime even without a TPO: you notify the council, and it has six weeks to make a TPO if it wants to keep the tree.
Do not rely on the old "dead, dying or dangerous" exemption: the 2012 Regulations narrowed it to genuinely dead trees (with prior notice) plus urgent danger works. If your report is silent on protection status and your area is leafy or historic, query it — missing a protected tree is one of the most expensive mistakes you can make.
Step 4: Read the recommendations and conclusions
This is where the arboriculturist tells you, in plain terms: which trees can go, which must stay, what protection is needed, and whether your scheme works. If the report recommends design changes — shifting a footprint out of an RPA, a no-dig surface, a special foundation — take them seriously. They are far cheaper to act on now than after a refusal.
Requirements are set locally — check your own council
Here is what a national guide cannot tell you: exactly what your authority expects. Because BS5837 is only guidance, the compulsion comes from each LPA's local validation list and how strictly its tree officer reads it — and both vary between councils. One authority may validate on a survey and constraints plan and condition the rest; another may want the full AIA, TPP and preliminary AMS up front.
So before you assume your report is complete, check what your specific council requires. PlanWatch tracks live tree-related planning activity per authority, so you can see how active and how strict your area is and search comparable applications. Start at the tree survey hub and compare authority pages such as Leeds, Manchester and Lambeth. Note the national dimension too: this walkthrough is England-centric — BS5837:2012 applies UK-wide, but Wales, Scotland and Northern Ireland run parallel but distinct regimes.
What a good report does and does not do
A good arboricultural report is evidence, not a decision. It should get your application validated and give the tree officer everything they need, but permission still depends on whether your layout protects the trees the council wants to keep. Heavy conflict with A-category or protected trees means either a redesign request or a fight.
Two quick quality checks on the report itself: it should name the author and their qualifications — an Arboricultural Association Registered Consultant or ICF Chartered Arboriculturist carries most weight — and reference BS5837:2012 in its methodology.
Where to go next
- The full package: what a BS5837 tree survey includes.
- Going with an application: tree surveys for planning.
- A post-permission condition: how to discharge an arboricultural planning condition.
- Vetting who wrote it: how to choose an arboricultural consultant, and tree survey cost.