Daylight and Sunlight Assessments in Kingston upon Thames

Kingston is a borough of semi-detached and short-terrace houses, and most of the work we do here is the rear extension that goes a metre or two further than the neighbour would like: single storey extensions of 4 to 6 metres in the streets off Kingston Hill, Coombe Road and Richmond Road, side and rear wraparounds in Surbiton and Berrylands, and two storey additions in New Malden and Chessington. We also see flats being created above shops on Brighton Road, Victoria Road and Kingston Road, where the question is daylight inside the new home.

Kingston's officers lean on the 45 degree rule as a first screen, and a scheme that crosses that line from a neighbour's window will usually be asked to show the effect with BRE evidence. Because the rule is a rough guide rather than a measurement, a surprising number of extensions that cross the line still meet the BRE guidelines once the geometry is modelled properly. Our Kingston reports are built to answer that exact question, usually within 4–5 working days.

Recent daylight and sunlight assessments in Kingston upon Thames

99 Brighton Road, Surbiton – new flat above a shop, with internal daylight

The owner of a shop on Brighton Road wanted to convert the first floor to a one-bedroom flat with a rear and side extension, and asked us to say plainly what should change if the daylight target was not met. The bedroom met the BRE guidelines, but the living room, lit by one front window and two rooflights, fell short as drawn. We marked up a third rooflight that brought the room over the target; the architect added it, and the report was based on the chosen rooflight sizes. The submitted scheme included three side rooflights.

Kingston granted the application on 8 August 2025 (24/02749/FUL).

89 Wolsey Drive, KT2 – single storey rear extension tested at two depths

An earlier prior approval application for a 6 metre rear extension had been refused, with loss of light to the neighbours among the reasons. The revised design was 5 metres deep with a pitched roof, and the designer wanted both depths and both roof forms tested so the evidence could support an appeal as well as the resubmission. We added the neighbours' missing windows to the model and tested every option: both depths and both roof forms met the BRE guidelines at the windows of Nos. 87 and 91.

The householder application for the rear extension was granted by Kingston on 4 June 2025 (25/01169/HOUF).

25 Cardinal Avenue, KT2 – side and rear extension beside a bay window

A homeowner on Cardinal Avenue was extending 4 metres to the rear and to the side, with pre-application advice flagging the neighbour's ground floor bay window. All of the neighbour's windows met the guidelines; one side pane of the bay fell marginally short on its own, but the BRE guide takes the centre pane of a bay as the main window for the room and that pane met the target, so the report quoted the BRE bay-window wording beside the results to make the position clear to the officer.

Kingston granted the application on 1 May 2025 (25/00120/HOU).

What Kingston planning officers look for

Kingston determines applications against its Core Strategy (2012) and the Kingston Town Centre Area Action Plan (2008), read with the London Plan, while a new borough-wide Local Plan is prepared. The amenity policies require development to protect neighbouring occupiers' daylight, sunlight and outlook and to avoid an overbearing or overshadowing relationship with adjoining homes.

In practice Kingston applies a 45 degree rule as a working guide: a line taken from the nearest habitable-room window of the neighbour, in plan and in elevation, that an extension should not cross. Where it does, or the position is marginal, the council expects the light impact to be examined more fully through a BRE assessment. We explain the rule and its limits in our 45 degree rule blog. The detailed householder guidance sits in the Residential Design SPD, and the numerical assessment follows BRE BR 209, Site layout planning for daylight and sunlight (2022 edition). The Local Plan and Core Strategy are at kingston.gov.uk/planning-and-building-control/planning-policy/local-plan and the Residential Design SPD at kingston.gov.uk/planning-and-building-control/planning-policy/supplementary-planning-documents/residential-design.

When you need an assessment in Kingston upon Thames

• A single storey rear extension of 4 to 6 metres on the semi-detached streets of Kingston Hill, Coombe and Norbiton that crosses the 45 degree line from a neighbour's kitchen or dining window.
• A larger home extension prior approval where a neighbour has objected, or a resubmission after an earlier scheme was not supported on light grounds.
• Side and rear wraparound extensions in Surbiton, Berrylands and Tolworth, where a bay window next door complicates the picture.
• Converting the floors above a shop on Brighton Road, Victoria Road or New Malden High Street into flats, where Kingston will want to see adequate daylight to the new living rooms.
• Two storey side extensions in Chessington and Hook, where the first floor affects bedroom windows next door.
• Any scheme where Kingston's pre-application advice has mentioned daylight, sunlight or the 45 degree rule.

How we work

We build a 3D model of the site and its neighbours from the drawings, photographs and survey data, run the BRE tests and send a report with results, plans and a plain conclusion. The fee is fixed and agreed up front and the report usually takes 4–5 working days. Where a result falls short we tell you what would remove the shortfall, and we will hold the report until you have decided so the submitted drawings match. The four tests are:

• Vertical Sky Component (VSC) – the sky a neighbouring window can see, before and after.
• No-Sky Line / daylight distribution (NSL) – how far daylight reaches into the neighbour's room.
• Annual Probable Sunlight Hours (APSH) – direct sun to windows within 90 degrees of south, over the year and in winter.
• Sun on ground – the share of a garden that gets two hours of sun on 21 March.

See our VSC, NSL and APSH page and our guide to the BRE guidelines for the detail, and our daylight and sunlight assessment page for the service.

Frequently asked questions in Kingston upon Thames

My extension crosses Kingston's 45 degree line. Does that mean it will not be allowed?

No. The 45 degree rule is a screening tool, and the council's policies turn on the actual effect on the neighbour's light. If the BRE tests show the windows stay within the guidelines, that evidence usually carries more weight than the line.

Can you test a 5 metre and a 6 metre version together?

Yes. At 89 Wolsey Drive we reported on two depths and two roof forms in one report, so the designer could choose and keep the alternative in reserve.

Does a flat above a shop in Surbiton need an internal daylight assessment?

Kingston will want to see that the new living rooms and bedrooms are adequately daylit, particularly where a room relies on rooflights. We test the rooms and, as at 99 Brighton Road, suggest the rooflight or window change that brings a room within the target before the report is written.

For sites across the river, our Richmond upon Thames page covers the same work there.

Get a fixed-fee quote

Send the drawings and the site address through our contact page or get an instant figure from the price calculator. Nick is on 01962 809155 and nick@sunlightassessments.co.uk.