Clipboard and measuring tape at the base of a tree during a site survey

What an arborist report tells Exeter owners

7 min read
Explained
An arborist report records a tree's condition, risks and recommended work, and planning officers, insurers and managing agents often ask for one when a tree becomes a question. This guide explains the main types of report, when each is needed, what a good report contains and how to judge the person writing it.

An arborist report tells an Exeter owner what condition a tree is in, what risks it presents, what it is worth to the site and what work, if any, it needs. It is the document that planning officers, insurers, solicitors and managing agents tend to ask for when a tree becomes a question rather than a background feature. There is no single format for a report, and the type you need depends on the reason you need it. This guide explains the main kinds of report, when each is required, what a good one contains and how to judge the person who writes it.

Condition surveys and risk assessments

The most common report is a condition survey. It records the species, height, stem diameter and crown spread of each tree, notes the health of the roots, stem and branches, and gives a view on structural faults such as cracks, included bark, decay or a lean. A good survey also assigns each tree a rating that reflects its condition and its remaining useful life, which helps an owner decide whether to retain, manage or remove it.

A risk assessment goes further. It asks what could happen if the tree failed, what targets lie beneath it and how likely a failure is. A tree over a footpath in a busy part of the city is a different proposition from a tree at the bottom of a quiet garden, even if the two have the same condition. Risk assessments are especially useful for trees near schools, care homes, car parks and shared driveways, where the consequences of a failure are high. They rarely give a simple yes or no, but they set out the reasoning, which is what most owners need.

BS 5837 surveys for development

If you are building, extending or demolishing anything near a tree, the planning authority may ask for a survey that follows the British Standard BS 5837:2012, Trees in relation to design, demolition and construction. The standard sets out how trees should be surveyed, categorised and protected during development. It introduces the concept of a root protection area, which is the part of the root zone that should be kept undisturbed, and it asks the surveyor to assess how the proposed development would affect each tree.

The usual structure is a tree survey, an impact assessment that shows what the scheme would do to each tree, and a protection plan that shows fencing, ground protection and any special working methods. Planning officers in Exeter use these documents to judge applications, and they often form the basis of conditions attached to a permission. The Planning Portal's guidance on trees explains that many trees are protected by a Tree Preservation Order and that others are covered by the controls that apply in conservation areas, so a development survey is the practical way to establish which trees a scheme must work around.

Development surveys need to be completed before design decisions are fixed, because the root protection area often determines where foundations, drives and service runs can go. A survey commissioned after the architect has finished the drawings usually leads to redesign, and the cost of redesign is generally higher than the cost of an early survey.

Qualifications to look for

The report is only as good as the person who writes it. The arboricultural profession does not have a single licensing regime, but there are recognised qualifications and professional bodies. The Arboricultural Association is the professional body for arborists in the UK, and its help and advice pages are a sensible place to start when you want to understand what a surveyor should hold. Look for a written qualification in arboriculture, evidence of professional indemnity insurance and experience of the particular type of report you need.

Ask to see a sample report before you commission one. A competent report will identify the surveyor, describe the methods used, state the date of inspection and the limits of the survey, and give recommendations that are clear enough to act on. A report that lists a tree as dangerous without explaining why, or that recommends felling as a first step without considering alternatives, should be treated with caution. A surveyor who is honest about uncertainty, and who recommends monitoring where the evidence is incomplete, is usually the more reliable choice.

What the report should contain

A useful report includes a site plan showing the position of each tree, a table of the trees with their species and condition, a description of any defects found, a risk or impact assessment and a set of recommendations with an indication of urgency. Where photographs support the findings, they should be dated and labelled. For development work, the report should also show the root protection areas and the constraints they impose on design.

The report should be written so that a non-specialist can understand it. Technical terms are useful when they are defined, and the surveyor should explain why each recommendation has been made. If the report is for planning, the council will expect a specific format and may request additional information. On historic sites the report has to be read alongside the designations, which are covered in the guide to trees at listed buildings and parks in Exeter. If the report is for an insurer or a legal dispute, the surveyor may need to attend a meeting or provide a statement, so it is worth asking at the outset what the report will be used for.

Commissioning a survey for an Exeter site

Start by deciding what question the report needs to answer. A general condition survey for an owner who wants to understand a large garden is very different from a development survey for a site that is about to be built on, and a subsidence investigation requires an engineer as well as an arborist. Being clear about the question keeps the scope and the cost sensible.

Timing matters as well, and the work that follows a survey is set out in the tree surgery timeline for Exeter gardens. A survey carried out in leaf, in summer, is the most informative time to judge the crown density, the presence of foliar disease and the balance of the canopy. A survey carried out in winter, with the tree leafless, makes the structure easier to read: the branch unions, the stem form, cavities and the fine twig growth that shows vigour are all more visible. Many surveyors recommend a leaf-off inspection for trees with suspected structural faults and a leaf-on inspection for trees where health is the concern, and a report that covers both gives the fullest picture. Ask the surveyor which season they plan to visit in and why.

Gather the information the surveyor will need before the visit. Title documents, planning history, any existing consents, photographs of the trees and details of the proposed work all help. For a site in Exeter, the council's planning records will show whether a conservation area or a Tree Preservation Order applies. A short enquiry through the quote form with the address, the number of trees and the purpose of the report is a good way to start the process.