Daylight obstruction from boundary walls and fences
Most boundary fences pass the 25 degree test without an assessment. Low windows, patio doors, basements and gardens are where walls and fences cause genuine loss.
Boundary wall daylight obstruction is raised in objections far more often than it is made out, and the reason is geometry. A 2 metre fence sitting 2 metres from a window whose centre is about 1.6 metres above the ground rises only about 11 degrees above that window centre. Established daylight guidance treats an obstruction subtending less than 25 degrees as unlikely to cause a problem, so a standard fence beside a standard window passes without an assessment. Where boundary structures do cause real loss is to low windows, patio doors, basement and lower ground floor rooms, and to gardens, which is a sunlight question rather than a daylight one.
When a boundary structure affects daylight
Three variables decide it: the height of the structure above the centre of the affected window, the horizontal distance between them, and the orientation.
The first two combine into an angle. Measure from the centre of the lowest affected window to the top of the wall or fence, and work out how far above the horizontal that line rises.
Illustrative arithmetic, using the geometry alone. A 2 metre fence at 2 metres distance from a window centred 1.6 metres above ground gives a rise of 0.4 metres over a 2 metre run, which is about 11 degrees. Bring the fence to 1 metre away and the same rise over a 1 metre run gives about 22 degrees. Raise the structure to a 3 metre wall at 1 metre and the angle jumps to roughly 54 degrees, which is the point at which it matters a great deal.
So height close to the window is what does the damage, not height in general.
Height limits under permitted development
Class A of Part 2 of Schedule 2 to the General Permitted Development Order 2015 permits the erection, construction, alteration, improvement or maintenance of a gate, fence, wall or other means of enclosure, within height limits.
The limit is 1 metre where the structure is adjacent to a highway used by vehicular traffic, or a footway of such a highway, and 2 metres elsewhere. Raising an existing fence above those limits is caught in the same way as building a new one.
The rights are withdrawn in the curtilage of a listed building, can be removed by condition on a planning permission, and can be removed by an Article 4 direction. On a corner plot the 1 metre limit applies to the whole frontage facing the highway, which catches owners who measure only the front boundary.
Hedges are different. Planting a hedge is not development at all, so no height limit applies under planning law. Where an evergreen hedge over 2 metres is causing a problem, the route is a high hedges complaint to the council under the Anti-social Behaviour Act 2003, after reasonable attempts to resolve it directly.
The 25 degree test and most fences
Published daylight guidance uses a two-stage approach. If the obstruction subtends an angle of less than 25 degrees to the horizontal, measured from the centre of the lowest affected window, daylight is unlikely to be noticeably reduced and no further assessment is needed.
Only where the 25 degree line is breached does the detailed calculation follow, comparing the vertical sky component at the window before and after. A retained value above the target figure, or a value no lower than around four fifths of the former value, is generally treated as acceptable.
| Situation | Typical outcome |
|---|---|
| 2 metre fence, 2 metres or more from a standard ground floor window | Passes the 25 degree test comfortably |
| 2 metre fence immediately against a standard window | Approaches the test, assessment sensible |
| 2 metre fence beside a patio door or floor-level glazing | Likely to breach the test |
| High wall adjoining a lower ground or basement window | Breaches the test, detailed calculation needed |
| Boundary structure to the south of a garden | Daylight test irrelevant, sunlight to the garden is the issue |
How local authorities apply those criteria varies, and the article on local plan amenity policies and how they use BRE 209 sets out the differences.
Windows that do fail
Four cases come up repeatedly.
Lower ground and basement windows, where the window centre may be below external ground level, so even a modest wall subtends a large angle. Patio doors and full height glazing, where the centre of the opening sits far lower than a conventional window. Single aspect rooms with one window facing the boundary, where there is no second source to compensate. And windows in a lightwell or narrow side passage, where the obstruction is on more than one side.
Add a fifth that is not about the window at all: a conservatory or garden room built close to a boundary, which then suffers from a fence erected afterwards and has no planning protection against it.
Sunlight to gardens and sitting areas
For outdoor space the relevant test is sunlight rather than daylight, and the usual benchmark is whether at least half of the amenity area receives at least two hours of sunlight on 21 March.
A high wall or close-boarded fence on the southern boundary of a small garden can fail that comfortably, and it is the complaint most householders actually feel. Sitting areas and growing space are affected the same way, and the piece on overshadowing of allotments, orchards and growing space deals with that case.
An overshadowing study is the document that tests it, and it is proportionate work on a householder scheme where the dispute is genuine.
Design alternatives that keep the light
Where a boundary structure is needed for privacy or security and daylight is the objection, there is usually a design answer.
Step the height down near the affected window, keeping the full height along the rest of the run. Use trellis or slatted panels in the upper section, which blocks sight lines while passing light. Set the structure back from the boundary by half a metre and plant in front of it. Finish the face towards the affected window in a light colour, which measurably increases reflected light into the room. Or substitute a hedge for the upper part, which grows in gradually and can be cut back.
None of these are concessions in design terms. A stepped fence with a trellis top usually looks better than 2 metres of close boarding.
What a neighbour can raise
Where the structure is permitted development, a neighbour has no planning route to object, because there is no application. Their options are a high hedges complaint if it is an evergreen hedge, a boundary ownership dispute if the position is contested, or a civil claim.
Rights of light is that civil claim, and it is not planning. It arises where a right has been acquired, usually by long enjoyment over twenty years under the Prescription Act 1832, and it is enforced in the county court rather than by the council. A planning officer cannot help with it and will say so.
Where an application is needed, because the structure exceeds the height limits or permitted development has been removed, the objection is a material planning consideration and evidence carries weight. What that evidence should look like is covered in objecting on daylight grounds and the evidence that carries weight, and a daylight and sunlight assessment is what settles a contested case.
Enter your postcode on PlanScope to see which documents a boundary or extension application near a neighbour's windows would need.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that works are permitted development.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
How tall can a fence be without planning permission?
Two metres, except where it is adjacent to a highway used by vehicular traffic or the footway of such a highway, where the limit is one metre. Raising an existing fence above the limit is treated the same as building a new one. The rights are withdrawn within the curtilage of a listed building and can be removed by condition or an Article 4 direction.
What is the 25 degree rule for daylight?
Published daylight guidance treats an obstruction that subtends less than 25 degrees to the horizontal, measured from the centre of the lowest affected window, as unlikely to reduce daylight noticeably. Only where that line is breached does the detailed vertical sky component calculation follow, comparing values at the window before and after the obstruction.
Can I object to my neighbour's new fence?
Only if it needs planning permission, which it usually does not. Where it is permitted development there is no application to object to. The alternatives are a high hedges complaint to the council if it is an evergreen hedge over two metres, a boundary ownership dispute, or a civil claim such as rights of light.
Do height limits apply to hedges?
No. Planting a hedge is not development, so no planning height limit applies. Where an evergreen hedge over two metres is causing a loss of light or amenity, the route is a high hedges complaint to the local authority under the Anti-social Behaviour Act 2003, after reasonable attempts to settle the matter directly with the owner.
How is sunlight to a garden assessed?
The usual benchmark is whether at least half of the amenity area receives at least two hours of sunlight on 21 March. A high wall or close-boarded fence on the southern boundary of a small garden can fail that test even where no window is affected at all, which is why gardens are assessed separately from rooms.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.