Tree risk assessment and the occupier duty of care
Tree safety duties are judged on the system, not on hindsight about one failed limb. Here is how to zone a site, set intervals, choose inspectors and record decisions defensibly.
If you own or occupy land with trees on it, you owe a duty of care to the people who could be hurt if one fails. That duty is not satisfied by a survey done for a planning application. It is satisfied by a proportionate, recorded inspection regime that matches the level of risk on your land, repeated at sensible intervals, with the findings acted on. Tree risk assessment and the occupier duty of care are about defensible process far more than about individual tree condition.
Where the duty comes from
Three strands combine. The common law duty of care in negligence applies to anyone whose acts or omissions could foreseeably injure others. The Occupiers' Liability Act 1957 sets the duty owed to lawful visitors, and the Occupiers' Liability Act 1984 extends a narrower duty to trespassers. Where trees sit on land used for a business, section 3 of the Health and Safety at Work etc. Act 1974 brings in the duty to persons not in the employer's employment.
None of these requires a guarantee against tree failure. The standard is reasonableness. Courts have consistently looked for a system of inspection that a reasonable landowner in that position would have operated, rather than for perfect prediction of a particular limb failing on a particular day.
That distinction is the whole of the practical advice. You are being judged on your system.
Zoning the site by target occupancy
The starting point on any holding larger than a garden is to divide it by how often people and property are present beneath or within falling distance of trees.
| Zone | Typical setting | Inspection approach |
|---|---|---|
| High occupancy | Car parks, play areas, footpaths, roadsides, buildings | Formal inspection at short intervals, recorded |
| Moderate occupancy | Field edges near dwellings, permissive paths | Formal inspection at longer intervals |
| Low occupancy | Woodland interior, land with no public access | Periodic overview, often from a distance |
Zoning lets you spend effort where harm could actually occur. A veteran oak in the middle of an inaccessible copse presents a different problem from the same tree over a village hall car park, and treating them identically wastes money on one and under-protects the other.
Reviewers should check that the zoning plan is drawn, dated and kept with the inspection records. A zoning exercise that exists only in the tree officer's head is worth nothing when it is tested.
Inspection intervals and who should inspect
Intervals follow from the zone, the tree population and known issues such as ash dieback. Annual or biennial formal inspection in high occupancy zones is common, with a longer cycle elsewhere and additional walkover checks after severe weather.
Competence is where organisations go wrong. A groundsman with a clipboard can carry out an informal walkover and report concerns. A formal inspection that assigns a risk rating and defers work for two years needs an arboriculturist with the training and experience to justify that call, and professional indemnity cover that responds if the call is wrong.
The Arboricultural Association publishes a directory of consultants, and membership grades give a reasonable proxy for competence. A Tree Survey prepared for a development is a different exercise with a different purpose, and it should not be filed as evidence that a safety regime exists.
Quantified and qualitative methods
Two families of method are in use. Quantified approaches, including the Quantified Tree Risk Assessment system, combine target occupancy, the probability of failure and the size of the part likely to fail, and express the result as a probability of harm compared against a tolerable threshold. Qualitative approaches assign categories of risk from a structured inspection.
Either can be defended. What cannot be defended is a method applied inconsistently, or a quantified output produced by someone who has not been trained in the system they are citing.
The National Tree Safety Group's approach to proportionate risk management is the reference point most inspectors work from in Britain, and it is explicit that trees are a low cause of harm overall and that management should be proportionate to that. Do not let a report drift into recommending removal of every tree with a defect.
Recording decisions so the system is defensible
The record is the product. Each entry should tie a tree or group to a location, a date, an inspector, the observations made, the decision taken and the date by which any work is to be done, followed by confirmation that the work happened.
- Map and number the trees or groups, including those on the boundary.
- Record the zone and the interval assigned to each area.
- Log each inspection with the inspector named and the method stated.
- Record the decision, including a decision to take no action and why.
- Track the works order through to completion and file the sign-off.
- Diarise the next inspection at the point the last one closes.
Boundary trees need care, since the duty follows occupation and control rather than the title plan. Boundary trees and shared ownership sets out how responsibility is usually divided and where it gets contested.
Acting on findings, and the protected tree problem
Proportionate works means the least intervention that manages the risk. Crown reduction, removal of a specific defective limb, bracing, target management such as moving a bench, or fencing off a zone are all legitimate answers, and they are often better than felling. Specifying the work properly matters, and specifying crown works councils will accept covers the language to use.
Where a tree is subject to a Tree Preservation Order or stands in a conservation area, consent rules still apply. The Town and Country Planning (Tree Preservation) (England) Regulations 2012 exempt works to remove an immediate risk of serious harm, and works to dead trees, subject to a notice requirement. For a dead tree you must normally give the local planning authority five working days notice before cutting it down, and in a genuine emergency you notify as soon as practicable afterwards.
Keep photographs and the inspector's written justification in both cases. The exemption is judged on the facts as they were, and an owner who removed a protected tree on a verbal assurance that it looked dangerous has no defence. Replanting duties can also follow a felling under an exemption, and the authority can serve a notice requiring a replacement tree where one has not been planted.
Conservation area trees follow a different route again. Six weeks notice to the council gives it the chance to make an Order, and the dead or dangerous exemptions apply in similar terms. Two councils will take two different views of what counts as immediate risk, so the inspector's written reasoning is what carries the decision.
Long term management on a development site is usually secured through a planning agreement, and long term tree management secured by planning agreement explains how those obligations are written.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
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Frequently asked questions
How often should trees be inspected?
Intervals follow from target occupancy rather than from a fixed national rule. Annual or biennial formal inspection is common where trees overhang car parks, paths, roads or buildings, with longer cycles in low occupancy areas and extra walkover checks after severe weather. Record the interval assigned to each zone and the reason for it.
Who is competent to carry out a tree safety inspection?
Informal walkover checks can be made by trained site staff who report concerns. A formal inspection that assigns a risk rating and defers work needs an arboriculturist with relevant training, experience and professional indemnity cover. Consultant directories and membership grades from the professional body give a reasonable starting proxy for competence.
Does a planning tree survey satisfy the duty of care?
No. A survey prepared to inform a development assesses trees in relation to design and construction, not the ongoing safety of people on the land. The two documents have different purposes and different scopes. Keep a separate inspection record with dates, inspectors, findings and the works that followed.
Can I fell a protected tree that looks dangerous?
Only within the exemptions. Works to remove an immediate risk of serious harm are exempt, and works to a dead tree require five working days notice to the local planning authority except in a genuine emergency. Keep photographs and written justification from the inspector, because the exemption is judged on the facts at the time.
Is felling the safest response to a defect?
Rarely. Proportionate management often means removing a specific limb, reducing a crown, installing a brace, moving the target such as a bench or path, or fencing an area. Guidance in Britain treats trees as a low overall cause of harm and expects management to reflect that rather than default to removal.
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.