Trees, daylight and the assessment nobody agrees on

Planning cannot make your neighbour cut their tree down. The planning system controls development, and a tree that has been growing in the garden next door for forty years is not development, so there is no application to object to and no officer with a power to intervene. That surprises people who have just spent a winter in a dark kitchen, and it is the first thing to be clear about before spending money.

What does exist is a narrower set of routes: a complaint procedure for high evergreen hedges, a consent regime where the tree is protected, a private law right to cut back what overhangs your boundary, and the treatment of tree shade in a daylight assessment where new building work is proposed. Each one answers a different question, and none of them is a general remedy for loss of light to trees.

Whether planning deals with trees blocking light at all

Two situations bring trees into a planning decision. The first is where a tree is affected by development, so its retention, protection or removal becomes a planning matter and a tree survey to the relevant British Standard is required. The second is where a tree already shades a site and a new building is proposed on it, in which case the tree's shade forms part of the existing baseline.

Neither gives a neighbour a remedy for an existing tree. A council cannot serve a notice requiring an unprotected tree to be reduced because it blocks light, and planning conditions cannot be imposed on land where no permission is being granted.

There is one indirect route worth knowing. Where a tree is protected by a Tree Preservation Order and the owner applies for consent to prune or fell it, the authority weighs amenity. Light to neighbouring windows is not the test, but a well-evidenced representation about the tree's effect on living conditions is a material consideration the authority will read.

The high hedges complaint and what it cannot do

Part 8 of the Anti-social Behaviour Act 2003 gives local authorities power to deal with complaints about high hedges affecting domestic property. The qualifying conditions are specific, and most complaints fail on them rather than on the merits.

The hedge must be formed wholly or predominantly of a line of two or more evergreen or semi-evergreen trees or shrubs. It must be more than two metres above ground level. It must act as a barrier to light or access. And the complaint must relate to the reasonable enjoyment of a domestic property.

So a single large tree is outside the scheme, however much shade it casts. A deciduous beech hedge is outside it. A line of leyland cypress at four metres is squarely within it. Councils charge a fee for the complaint, set locally, and most require evidence that you have tried to resolve the matter with the hedge owner first, which means keeping copies of the letters you sent.

Where the complaint succeeds the authority issues a remedial notice specifying works and a compliance period. The notice cannot require the hedge to be removed altogether and cannot require it to be reduced below two metres. Either party may appeal to the Planning Inspectorate.

Protected trees and consent to prune

If the tree is covered by a Tree Preservation Order, works to it need the authority's written consent, applied for under the 2012 regulations. If it stands in a conservation area and is not already protected, six weeks' written notice to the authority is required before works, during which the authority may make an order.

Exemptions exist for trees that are dead, and for work urgently necessary to remove an immediate risk of serious harm, with a notice requirement. Those exemptions are narrow and they are not a route to dealing with a shade problem.

As the neighbour, you can write to the authority when an application or notice appears. Set out the effect on specific rooms with dates and photographs rather than a general complaint, because a tree officer weighing amenity will give weight to evidence about living conditions even though light is not the statutory test.

Modelling existing tree shade in an assessment

Where new development is proposed, the daylight and sunlight guidance treats trees differently from buildings. Canopies are porous, the degree of obstruction changes through the year, and modelling a tree as a solid mass overstates its effect.

The usual approach is to report the result both with and without the trees modelled, and to state the transmittance assumption used. That matters most for sunlight to gardens and amenity areas, where a mature canopy can dominate the result, and it is why an overshadowing study should say whether existing vegetation was included.

The argument that follows is predictable. An applicant wants trees in the baseline, because it lowers the existing light levels against which the proposal is compared. An objector wants them out, on the basis that trees can be pruned and buildings cannot. Both points are fair, which is why reporting both runs is the only position that holds up.

Deciduous and evergreen canopies

A deciduous canopy in leaf between roughly April and October blocks the summer sun and lets winter light through. An evergreen canopy blocks all year. For a north-facing kitchen window, the evergreen is far the worse problem, because the loss falls in the months when there is least light to lose.

This distinction drives the high hedges scheme, which is limited to evergreen and semi-evergreen species for exactly that reason. It also matters in a daylight model, where applying a single annual transmittance figure to a deciduous tree will misrepresent both the winter and summer positions. If the assessment is being done properly, the seasonal difference should appear in the method.

Growing conditions complicate it further. A hedge trimmed annually to three metres behaves differently from one left to reach eight, and a surveyor reporting current height without noting the management regime is describing a moment rather than a condition.

Where the dispute is private

Three well-established private law positions, none of which involves the council. You may cut back branches and roots that cross your boundary, up to the boundary line and no further, and the cuttings belong to the tree owner, so offer them back. You cannot enter the neighbour's land to do it without permission. And there is no right to light over a tree, because rights of light attach to defined apertures and buildings rather than to vegetation.

A nuisance claim can succeed where roots cause damage or branches cause physical interference. Loss of light alone will not support one. For most householders the useful conclusion is that negotiation, perhaps with a shared contractor and a split cost, achieves more than any of the formal routes, and achieves it in weeks.

What a householder can actually do

Four steps, in order of cost.

1. Write to the neighbour with a specific proposal and a contractor's quote attached.
2. Check the council's tree map or planning register for a Tree Preservation Order or conservation area designation before touching anything.
3. If the trees are evergreen, over two metres and in a line, make a high hedges complaint and pay the council's fee.
4. If your own extension is the issue, deal with the shade in the design and in the daylight assessment rather than expecting the tree to change.

Our worked note on a single storey rear extension shows how existing shade is handled in that calculation.

What not to do is top a protected tree and argue about it afterwards. Unauthorised works to a protected tree are a criminal offence, the fines are not trivial, and a replacement notice can follow.

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