Specifying crown works correctly in a tree application

An application to work on a protected tree is refused or returned more often for wording than for arboriculture. "Cut back overhanging branches" and "reduce by 30 per cent" are not specifications. The council has to grant consent for defined works, and if it cannot tell from your form exactly what will be cut, it either refuses, asks for more information, or grants something narrower than you wanted.

Use the standard terms, give the finished dimensions, and the officer can say yes.

Why vague wording fails

Consent under a Tree Preservation Order is granted for the works described in the application, under the Town and Country Planning (Tree Preservation) (England) Regulations 2012. In a conservation area the equivalent is a section 211 notice giving the council six weeks to decide whether to make an order, and that notice has to describe the works too.

Either way the description becomes the thing you are permitted to do. If it says "reduce", a contractor can take a metre or four metres and both are arguably within it, which is why tree officers will not grant it. Work carried out beyond the consent is an offence, and the penalties for unauthorised works to a protected tree are substantial.

The industry standard for describing tree work is BS 3998, Tree work: recommendations. Officers mark against its vocabulary. Use any other wording and you are asking them to interpret.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified arboriculturist before relying on it.

Crown lifting

Crown lifting removes the lowest branches to raise the height of the bottom of the canopy. Specify it as a finished clearance height above ground level, and say over what area.

"Crown lift to give 2.5 m clearance above ground level over the garden, and 5.2 m over the adopted highway." That is a specification. The highway figure matters because highway authorities commonly want clearance over the carriageway for high-sided vehicles and a lower figure over the footway, so check what the local standard is before you write a number.

Two constraints are worth knowing. Lifting works best as the removal of whole branches at their point of origin rather than the shortening of them, and arboricultural practice generally keeps the live crown at no less than about two thirds of the tree's total height. A mature oak lifted to 6 m on a 9 m stem has lost its shape permanently.

Crown reduction

Reduction shortens the branches across the crown to make the tree smaller while keeping its form. The common mistake is to express it as a percentage.

Describe it two ways at once. State the length of branch to be removed, measured from the tips, and state the dimensions the crown will finish at.

"Crown reduce by up to 2 m, to leave a finished crown height of approximately 9 m and a radial spread of approximately 4 m from the stem, all cuts to a suitable growth point in accordance with BS 3998."

That last clause matters. Reduction cuts should go back to a live lateral branch of sufficient size to take over, not to a blind stub, and the standard sets out how that is judged. Trees reduced by indiscriminate shortening respond with dense weak regrowth that needs cutting again in three years.

Thinning, and why a percentage is allowed here

Thinning is the one operation where a percentage is the right unit, because you are removing a proportion of the leaf area evenly through the crown without changing its outline. Most practitioners work at 10 to 20 per cent and treat 30 per cent as an upper limit, taken from secondary branches rather than from the main structure.

Thinning is also the operation most often requested for the wrong reason. It lets slightly more light through and it does very little for wind loading, so if the aim is to reduce shading of a garden or a window, a reduction on the relevant side will usually do more. Say which it is.

Pollarding and veteran trees

Pollarding is the repeated removal of the crown back to a set of permanent points on the stem or primary branches. Starting a pollard on a mature tree that has never been pollarded is a serious intervention, and councils refuse it on amenity trees unless there is a sound reason. Where an existing pollard is being re-cut, say so, and give the height of the pollard points.

Veteran and ancient trees need different language again. Retrenchment pruning, which mimics the natural shedding of a crown over decades, is specified as a gradual reduction over several visits rather than a single operation. Deadwood in a veteran tree is habitat and should normally stay unless it is over a target. Where a veteran is involved, the application needs an arboricultural report with it rather than a form on its own.

Show the works on a plan

Number the trees and give the council a plan. If a tree survey has been done to BS 5837, use its reference numbers so the officer can cross-check species, height and condition without visiting.

For individual branch removal, mark the branch on a photograph. It takes five minutes and removes any argument later about what was agreed. Where several trees are being treated differently, set the works out as a schedule, one row per tree, rather than a paragraph of prose covering all of them.

Include the reason for each operation in the same schedule. An officer deciding whether the loss of amenity is justified is weighing the works against the reason, and a schedule that gives both is far easier to approve than one that gives neither.

Match the specification to the reason

The reason determines what should be written. A few recurring ones:

1. Shading of a window or garden: specify a directional reduction on the relevant side, with the finished spread stated, rather than an all-round reduction.
2. Branches touching a building or gutter: specify clearance in metres from the structure, not "cut back to the boundary".
3. Deadwood over a path or parking area: specify crown cleaning with a minimum diameter for the material removed.
4. Structural concern in the tree: attach a report. A council will not take a structural claim on trust.
5. Alleged damage to drains or foundations: this needs evidence linking the tree to the damage, and our note on trees, drainage and root ingress explains what that evidence looks like.

Where development is involved rather than maintenance, the root protection area governs what can happen around the tree as well, and the calculation for multi-stem trees catches people out. Our piece on root protection area calculations sets out the method. If consent is granted with a replanting requirement, check how long it binds you, which we cover in tree replacement conditions.

An illustrative case: a householder applied to "reduce a large sycamore overhanging the garden". Refused, as undefined. The resubmission asked for a 1.5 m reduction to the southern and western aspects only, leaving a finished spread of about 5 m, with cuts to suitable growth points to BS 3998, because the rear bedroom lost daylight after midday. Approved in four weeks.

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