There is no single fixed interval — it depends on why the survey exists. For a planning application, a BS5837 survey should generally be no more than about 12 months old, because tree condition, size and root protection areas change. For ongoing safety, inspection intervals are risk-based, typically annual to every few years. During construction, the frequency is set by your planning conditions.
The right answer to "how often should a tree survey be carried out?" depends entirely on the survey's purpose. A survey supporting a planning application, a survey for tree-safety management, and monitoring during construction all follow different clocks — and confusing them is a common and expensive mistake.
For planning: the ~12-month validity window
A BS5837 tree survey for planning is a snapshot in time. Trees grow, decline, get damaged in storms, or are worked on — and their root protection areas, which are calculated from stem diameter at 12 × the measurement, shift with them. A tree that grows from a 400mm to a 500mm stem widens its RPA radius from 4.8m to 6m, which can change whether your foundations conflict with it. So authorities expect the survey underpinning an application to be current.
As a practical rule of thumb, that means within roughly 12 months. If your survey is older than that by the time the application is submitted or determined, the tree officer may treat it as out of date and ask for an update before validating or deciding the application. This isn't a fixed statutory figure — it's a judgement the authority makes — but the older the survey, the more likely it is to be challenged, and the practice varies from one authority to the next.
When a re-survey is definitely needed for planning
- The survey is more than about a year old.
- A surveyed tree has been felled, pruned, storm-damaged or has visibly declined.
- The scheme has changed such that different trees are now affected.
- A neighbouring tree that constrains the site has changed materially.
Worked example: the stalled application
Say you commissioned a survey in spring, then the project paused for financing and you didn't submit until eighteen months later. In the interim a winter storm tore a major limb off a category B oak on the boundary, dropping it toward category U. Your original survey now overstates the tree's value and understates the risk. When the tree officer visits and sees the damage, the application can be held at validation until an updated survey and possibly a revised impact assessment are provided. A modest refresh fee up front would have avoided months of delay — see how much a tree survey costs for the numbers, which are far smaller than the cost of a stalled application.
For tree safety: risk-based intervals
Away from development, landowners have a duty of care to manage the risk from their trees. There is no single legal re-inspection interval; the frequency is risk-based. A qualified arboriculturist carries out an initial tree risk assessment and then sets a re-inspection schedule based on the trees themselves, their condition, and what they could hit if they failed — the "target".
In broad terms:
| Risk level | Typical example | Common interval |
|---|---|---|
| Higher | Large, mature or defective tree overhanging a road, car park, footpath, school or building | Often annual |
| Moderate | Trees in areas of regular but lower footfall | Every 1–3 years |
| Lower | Trees in low-occupancy areas with little below them to strike | Every few years |
The professional who inspects the trees recommends the interval; don't set it arbitrarily yourself. After severe weather — high winds, prolonged drought, or heavy snow load — a higher-risk tree may warrant an additional check outside its normal cycle, regardless of when the last inspection fell.
During construction: whatever the conditions say
If your development has planning permission with tree conditions, monitoring frequency is set for you. An Arboricultural Method Statement and any arboricultural site-supervision condition will specify how often the arboriculturist must attend to check that protective barrier fencing, construction exclusion zones and working methods are being followed. Here the "how often" is dictated by the planning condition, not by your own judgement — and breaching it is an enforcement matter that can render works unlawful. Remember too that you cannot lawfully begin site works at all until any pre-commencement condition requiring a detailed method statement and tree protection plan has been discharged in writing.
Protected trees change the picture too
Whatever the interval, remember that survey findings don't override the separate statutory protection on Tree Preservation Order and conservation-area trees. A survey telling you a tree is in poor condition does not give you licence to remove it — that still needs the authority's written consent (or the correct conservation-area notice, which requires six weeks' advance notification). The exemptions are narrow: a genuinely dead tree (with prior notice to the authority), or urgent works to remove immediate danger — the 2012 Regulations replaced the older "dead, dying or dangerous" test, a trap for homeowners who still cite the old wording. Removing or pruning a protected tree without consent is a criminal offence carrying substantial fines. Re-check protection status with a TPO check whenever you plan works, not just when a survey happens to be due.
Intervals are set locally — check your council
Just as with the requirement for a survey in the first place, re-survey expectations are a matter of local judgement, not national rule. Whether a tree officer treats a 13-month-old survey as still current, or insists on a refresh, is decided authority by authority, and validation practice genuinely differs between councils. There is no universal "surveys expire after X months" statute — only the local tree officer's view of whether your information is current enough to rely on.
So when you're planning timing, check your own authority's expectations rather than assuming a national standard. PlanWatch tracks live tree-related planning activity per council, so you can see how trees are being handled where you're building — compare, for example, Leeds, Nottingham or Lambeth, and look up your own area from the tree surveys hub. This guidance is England-centric; validation practice and tree-protection law differ in Scotland, Wales and Northern Ireland, so check the relevant national regime if you're building outside England.
The bottom line
- Planning: keep it under ~12 months; refresh if the trees or scheme change, and check your council's own view of currency.
- Safety: risk-based, typically annual to every few years, set by a qualified arboriculturist and revisited after severe weather.
- Construction: the frequency written into your planning conditions and method statement.
For what a survey actually involves and how long each one takes, see our guides to the BS5837 survey process and how long a tree survey takes.