A boundary wall raised to two metres and the light lost

A boundary wall of up to two metres is usually permitted development, and that is why a neighbour who has lost light to a ground floor window often finds there is no application to object to. Boundary wall height rules sit in Schedule 2 Part 2 Class A of the General Permitted Development Order 2015: one metre where the wall or fence is next to a highway used by vehicles, or the footway of such a highway, and two metres everywhere else. Above those heights, planning permission is needed.

So the light question splits in two. If the wall is within the permitted limits, the planning system is largely out of it. If it is above them, or permitted development has been removed, the effect on daylight becomes a material consideration.

What Part 2 Class A allows

Class A covers gates, fences, walls and other means of enclosure. The two heights are the whole of it, and a few restrictions take the right away:

• Within the curtilage of a listed building, no means of enclosure is permitted development.
• Works that involve demolishing or altering a wall that is itself listed, or in the curtilage of a listed building, need consent.
• An Article 4 direction can remove the right for a defined area, and in some conservation areas and estate areas it has been removed.
• The right does not apply where a condition on an earlier permission removed it, which is common on newer housing estates.

Trellis on top of a fence counts towards the height. People add 600 millimetres of trellis to a 1.8 metre fence and assume it is exempt because it is open. It is not, and the combined height is what matters.

Height is measured from ground level at the base of the structure. Where the gardens are at different levels, which side you measure from changes the answer, so this is the point to put in writing to the council rather than guess.

What a raised boundary does to a ground floor window

A wall two metres from a window has a much larger effect than the same wall ten metres away, because what matters is the angle it subtends at the window, not its height on its own.

The standard planning test comes from the Building Research Establishment guidance on site layout planning for daylight and sunlight. Draw a line from the centre of the lowest window on the affected elevation, at 25 degrees above the horizontal, towards the obstruction. If the top of the wall sits below that line, the guidance treats daylight as unlikely to be materially affected and no further assessment is normally needed. If it breaks the line, a fuller calculation of the vertical sky component is the next step, and the guidance then looks at whether the remaining value is less than about 0.8 of what it was before.

For a two metre wall, the line is broken where the window is close to the boundary and low in the elevation. A kitchen window one and a half metres from a boundary wall, with its sill at 900 millimetres, is the classic case. A first floor bedroom is almost never affected.

The practical reading of that is uncomfortable but honest: the wall most likely to cause a real loss of light is also the one most likely to be permitted development.

Narrow gardens and basement or lower ground rooms

Two situations deserve more than the 25 degree check. The first is a long narrow garden where the neighbour's habitable room looks across a two or three metre gap. The second is a lower ground floor or semi-basement room, where the window head may sit at or below the external ground level and the wall removes most of the visible sky.

Where a lower ground room is involved, the assessment approach is different and the reasoning is set out in the note on daylight to a basement flat conversion. Sunlight is a separate question from daylight, and a wall on the southern boundary of a small garden can take away direct sun from a patio even where the window test is passed. The usual measure for ground level is the proportion of the amenity area receiving a given number of hours of sun on 21 March, and an Overshadowing Study is the document that sets that out.

When permission becomes necessary

Permission is needed for a wall above two metres, or above one metre next to a vehicular highway, and for any means of enclosure in the curtilage of a listed building. It is also needed where an Article 4 direction or a planning condition has removed the right.

At that point the effect on neighbouring light is a material consideration, and so are appearance, enclosure, the loss of an open outlook and highway visibility where the wall is near a junction or an access.

If you want certainty rather than an opinion, a certificate of lawfulness for proposed use or development under section 192 of the Town and Country Planning Act 1990 is the only formal way to confirm that works are lawful. It is a paid application with a determination period, and it produces a document a future buyer's solicitor will accept.

Sorting it out without an application

Most of these disputes are better solved on the ground than on paper.

1. Measure the existing and proposed heights on both sides, with photographs and a tape in shot, before anyone starts.
2. Ask for the wall to be stepped down over the length nearest the affected window. A wall that drops from two metres to 1.2 metres for three metres of its run often resolves the light issue completely.
3. Consider an open or part-open construction, such as slatted panels or a hit-and-miss fence, for the section nearest the window.
4. Agree the position relative to the boundary. Where a new wall is built astride the line of junction, the Party Wall etc. Act 1996 gives a notice procedure that is separate from planning and worth following.

Rights of light are a civil matter with their own law and their own remedies, and they do not depend on planning permission at all. The difference is explained in the note on rights of light against planning amenity, and it is the point most householders get wrong.

Evidence if an application is made

Where permission is required and light is the issue, submit a dimensioned section through the boundary showing the existing and proposed wall, the neighbouring window and the 25 degree line from the centre of that window. One accurate section answers the question faster than several pages of prose.

Add a plan showing the distance from the wall to the affected window, a note of the window's use, and photographs from inside the neighbouring room where access is given. Where the 25 degree line is broken, a Daylight and Sunlight Assessment carrying the vertical sky component figures is the proportionate response.

If you are the neighbour objecting rather than the applicant, the structure of a useful objection is set out in the note on answering a neighbour daylight objection. Measurements and a section carry weight. Adjectives do not.

Enter your postcode on PlanScope to see which reports a boundary or extension proposal is likely to 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 lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.