Specifying crown works councils will accept

A crown reduction specification that says "reduce by 30 per cent" will be refused, returned or approved in terms nobody can enforce. Councils need to know what the tree will look like when the contractor packs up, and a percentage does not tell them. Percentage of what: height, spread, canopy volume, leaf area. Four people will give four answers and the tree officer who visits in two years cannot say whether the consent was complied with.

The fix takes ten minutes. Write the specification in the terms the British Standard uses, give a measurable quantity, and attach a reason to every item.

The operations, defined

Getting the vocabulary right matters because these words have settled meanings and using them loosely is what causes the confusion.

Crown reduction reduces the height and spread of the crown while keeping its shape and leaving a viable structure. It is done by cutting back to suitable growth points, not by heading branches back to a stub.

Crown thinning removes a proportion of the secondary branch growth throughout the crown to give a more even density of foliage, without changing the size or shape of the crown. It does far less for light than people expect, and heavy thinning stresses the tree and prompts vigorous regrowth.

Crown lifting removes the lowest branches to give clearance beneath, specified as a height above ground level. It is the operation that most often solves a real problem, such as clearance over a footway or a driveway.

Pollarding is the repeated removal of all branches back to a set framework, and it is only appropriate for a tree that has been managed that way before or for a species that tolerates it. Starting a pollard on a mature tree that has never been pollarded is a major intervention and councils treat it accordingly.

Deadwooding removes dead branches, usually for safety where there is a target beneath.

Making the quantity measurable

British Standard practice moved away from percentage reductions towards specifying either the length of growth to be removed or the dimensions of the resulting crown. Both work. Use one of them.

Length of growth to be removed reads like this: reduce the lateral branches on the south and west aspects by up to 2 metres in branch length, cutting back to suitable growth points of at least one third of the diameter of the branch being removed.

Resulting dimensions read like this: reduce the crown to a finished height of approximately 9 metres and a radial spread of approximately 4 metres from the stem, retaining the natural form of the crown.

For thinning, state the percentage of secondary growth and keep it modest. For lifting, give a height above ground level and say whether it applies all round or only over the highway.

Two details that separate a professional specification from an amateur one. Say where the work applies, using compass aspects or a numbered branch plan rather than "the side facing the house". And say what the cuts should achieve, because a specification that produces a row of stubs has failed even if the dimensions are right.

Justifying each item

Councils assess these applications against the amenity value of the tree. The question is not whether you want the work done. It is whether the work is reasonable given what the tree contributes.

Tie each item to something concrete.

• A structural defect, evidenced by a photograph and, where the defect is internal, by a decay assessment.
• A target beneath: a footway, a parking area, a conservatory, a play area.
• A clearance requirement: over a highway, from a building, from a service line.
• Light or overshadowing to a habitable room, described with orientation, distance and the effect.
• Deadwood over a target.

What does not work: "the tree is too big", "leaves block the gutters", "it takes light from the garden in general", or a bare assertion that the tree is dangerous. Where the case rests on condition, an Arboricultural Impact Assessment or a shorter arboricultural report from a suitably qualified author gives the officer something to rely on, and councils expect that work to be done by someone competent.

Where the tree has to come down, applications for felling are decided differently and replacement planting is nearly always expected. Set the replacement out properly, with species, size at planting, position and aftercare, in a Landscape Strategy or as a planting schedule on the drawing.

Timing, cycles and repeat work

Ask for a cycle rather than a one-off where the work will need repeating. A crown lift over a footway will need doing again in four or five years, and a specification that says so is easier for an officer to approve than a series of applications that each look like an escalation.

Seasonal timing matters for three reasons.

Species tolerance. Some species bleed heavily if pruned in spring, and some tolerate work better in the dormant season. A contractor should advise.

Wildlife. It is an offence to damage or destroy the nest of a wild bird while it is in use or being built. The bird breeding season runs broadly from March to August, and a consent to carry out tree work is not a defence. Trees with cavities, dense ivy or loose bark may support roosting bats, which are protected, so a check by a qualified person is needed before work on such trees.

Consent duration. Most consents are time limited, and letting one lapse means starting again.

Getting the application form right

The mechanics catch people out as often as the wording does.

Identify the tree by the reference used in the order, not by its position in the garden. Orders schedule trees as T1, T2, G1 for a group or A1 for an area, and an application referring to "the large oak at the rear" forces the officer to work out which tree is meant.

Supply a plan. A block plan with the tree marked, the building outlined and north indicated. Where several trees are involved, number them on the plan and use those numbers throughout the specification.

Say who owns the tree. Works to a neighbour's tree still need consent from the council, and the council will notify the owner. Overhanging branches can be cut back to the boundary at common law, but that right is displaced where the tree is protected, so consent is still needed.

There is no fee for an application for works to a protected tree, which is worth knowing because it removes any reason to bundle several years of work into one speculative application.

Recording what was done

Photograph the tree before the work from fixed positions, and photograph it afterwards from the same positions. Keep the consent, the specification and the contractor's invoice together.

This matters more than it sounds. Where a council later alleges that work went beyond the consent, the before and after record is the evidence. And where the work was carried out by a contractor who exceeded the specification, the owner needs to be able to show what was instructed.

If you are unsure whether the specification will be accepted, send the draft to the tree officer before submitting. Most will comment informally, and a specification agreed in advance is approved as submitted. For anything involving a mature tree close to a building or a proposed development, having the report reviewed by a qualified arboriculturist before it goes in is worth the fee.

This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional before relying on it. To see whether a property has protected trees or other constraints, check whether a site has tree constraints.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.