Daylight and Sunlight assessments in Wandsworth

Wandsworth's housing is tall and tightly packed, and the schemes we assess here reflect it: basement and lower-ground flats in Putney and Balham being extended into the garden with a lowered floor, three-storey rear extensions on the Victorian terraces of East Hill, Wandsworth Town and Battersea, and conversions that put bedrooms below ground behind a lightwell. The question is seldom a single window; it is a stack of flats behind, a garden split between two households, and levels that change from one end of the plot to the other.

Wandsworth also has an engaged population of neighbours, and the comments on an application frequently raise daylight. A report here has to anticipate those questions: why a north-facing window is not sunlight-tested, why the model uses one fence height rather than another, and what happens to the garden at the back. The three examples below show how we deal with that.

Recent daylight and sunlight assessments in Wandsworth

67 Disraeli Road, Putney, SW15: rear and side extension to a basement flat

A single-storey rear and side extension with a lowered floor level to a basement flat, next to the flats at 65 and 69. The owner wanted the dig-down and the changing garden levels reflected accurately. The most affected neighbouring window retains 88% of its former daylight, above the BRE benchmark of 80%, and sun on the ground in both neighbouring gardens stays well above the 50% target. The neighbouring rear windows face roughly north, so the annual sunlight test does not apply to them, and the report says why. Application 2025/4662 was approved with conditions on 5 June 2026.

135 East Hill, SW18: one storey or two above an existing extension

A developer wanted to know whether one or two additional storeys could go on top of an existing ground-floor rear extension without harming the light to the neighbour at No. 139. We tested both options and produced two reports. The single-storey option met the BRE guidelines at every neighbouring window; the two-storey option met them at all but one window, which the report identified and explained. With both in hand the client could weigh the extra floor against that one result. The application that went forward, for a three-storey rear extension with a roof terrace, 2025/4328, was approved with conditions on 10 February 2026.

Nightingale Lane, Balham, SW12: basement flat lit by lightwells

A house on Nightingale Lane being converted into flats, one with basement bedrooms lit by lightwells. The architect wanted two layout options tested so the client could choose between a rear flat with basement and a front flat with basement. Each option report showed daylight maps over the plans, and because basement rooms live or die by the lightwell, the report specified white-painted lightwell walls and light-coloured floor tiles: cheap choices that noticeably lift the daylight reaching the room. The report was updated for the revised plans and issued for the planning submission in 2026.

What Wandsworth planning officers look for

Wandsworth determines applications against the Wandsworth Local Plan, adopted in July 2023, read with the London Plan. Its design and amenity policies require development to protect neighbouring occupiers' daylight and sunlight, and Policy LP27 sets housing standards that include adequate daylight and sunlight within new homes, which is why basement and lower-ground flats are tested internally. The council applies BRE 209, Site layout planning for daylight and sunlight (2022 edition).

For extensions, basements, roof alterations and loft conversions the Housing SPD explains how those policies apply to houses and flats and is the document officers quote when asking for a report. The Local Plan is at wandsworth.gov.uk/planning-and-building-control/planning-policy/local-plan/the-adopted-local-plan and the Housing SPD at wandsworth.gov.uk/planning-and-building-control/planning-policy/spd-and-guidance/housing-spd.

When you need an assessment in Wandsworth

• Rear and side extensions to basement and lower-ground flats in Putney, Southfields and Balham, especially with a lowered floor or changing garden levels
• Two- and three-storey rear extensions on the terraces of East Hill, Wandsworth Town, Battersea and Earlsfield, where several flats behind share one rear elevation
• Conversions creating basement bedrooms lit by lightwells in Balham, Clapham South and Tooting, where the council wants the new rooms' daylight shown
• Roof terraces and upward extensions that add height close to a neighbour's rear windows
• Any application where neighbours' comments have raised daylight or sunlight, or where you expect them to

How we work

Send drawings and photographs and we build the 3D model of the scheme, the neighbours and the garden levels ourselves. The fee is fixed and agreed up front; a report usually takes 4–5 working days, and where there are two design options we can test both and report them separately. The service is described on our daylight and sunlight assessment page. Every neighbour report runs the four BRE tests:

• VSC for daylight at each neighbouring window, with the before-and-after ratio against the 80% benchmark
• NSL for daylight distribution within rooms
• APSH for annual and winter sunlight to windows within 90 degrees of south
• Sun on ground for gardens: two hours of sun on at least half the area on 21 March

For new basement and lower-ground rooms we test daylight under the 2022 BRE method. The tests are explained on our VSC, NSL and APSH page and the benchmarks on our BRE guidelines page.

Frequently asked questions in Wandsworth

My neighbours' rear windows face north. Why does your report not test their sunlight?

Because BRE 209 applies the sunlight test only to windows facing within 90 degrees of due south; a north-facing window receives little direct sun before or after. The report states the orientation and the rule so the point is clear to anyone reading it.

I am extending a basement flat with a dig-down. Does the lower floor level matter?

Yes, and it usually helps. A lowered floor can reduce the height of the extension above the neighbour's ground, which is why we rebuild the model to the latest levels rather than work from a planning drawing alone, as at Disraeli Road.

Can you assess two design options before I decide which to submit?

Yes. At East Hill we tested one and two storeys and issued a report for each; at Nightingale Lane two layouts were reported in a morning. You then submit the option you choose with a report that matches it.

Get a fixed-fee quote

Send your drawings through our contact page or get an instant figure from the price calculator. Call Nick on 01962 809155 or email nick@sunlightassessments.co.uk; if your site is on the Clapham or Brixton side of the boundary, see our Lambeth page.