Daylight & Sunlight Assessments in Sutton

Sutton is a borough of interwar semis and short side passages, and that is what most of our work here looks like: side extensions and rear dormers in Wallington and Carshalton, single-storey rear extensions in Worcester Park and Cheam, and the occasional block of flats replacing a redundant building on a main road. Because the flank wall of a semi often carries the neighbour's kitchen or landing window, a side extension that looks modest on plan can take a large slice of that window's sky, and that is where most of the questions arise.

Two things set Sutton apart. First, householder applications here attract a noticeable number of public comments, and it is not unusual for a neighbour to commission their own daylight report, so the applicant's report must stand up to being read against another consultant's. Second, officers lean on the 45-degree and 25-degree checks in the Design of Residential Extensions SPD as a first screen, then ask for BRE testing when a scheme crosses them. All three of the jobs below involved one or both.

Recent daylight and sunlight assessments in Sutton

22 Sandhills Road, Wallington, SM6: side and rear extensions and rear dormer

Side and rear extensions and a rear dormer to a semi-detached house, heading to planning committee after a daylight report for the neighbour at No. 24 had raised concerns. The architect needed an independent report robust enough to be read alongside it. Tested in isolation, the neighbour's side kitchen window retained around 70% of its VSC, below the 80% benchmark, and the report said so; but the kitchen is also lit through a glazed door, and assessed as a whole room it retains 81%, within the guideline. Every other window, the sunlight tests and the garden met the guidelines. Application DM2026/00809 was granted at committee on 22 October 2026.

213 Longfellow Road, Worcester Park, KT4: single-storey rear extension

A single-storey rear extension where another consultant was already involved, so the report had to be technically complete and able to withstand expert scrutiny. We set an enhanced scope: VSC, NSL, APSH and sun-on-ground for the adjoining house, plus 21 March shadow plots. To pre-empt any suggestion that the model was incomplete, the whole row of neighbouring houses was included, the neighbour's conservatory went on the window map and fence heights were checked against the drawings. No design changes were requested. Application DM2025/00394 was granted on 29 August 2025.

Cheam Common Road, Worcester Park: 21 flats replacing an unused building

A block of 21 flats replacing a disused building, needing a neighbour report for Rylands Court next door and an internal daylight report for every new home. The design changed several times, with three units added and the first and second floors reshaped. On the final layout every first and second floor room met the guidelines; two ground-floor bedrooms, Units 3 and 8, did not until we proposed widening their windows with the heights unchanged. The architect adopted both, and the application is being prepared for submission.

"Thank you for suggesting the solution for Units 3 and 8, both work." (architect)

What Sutton planning officers look for

Sutton determines applications against the Sutton Local Plan 2016 to 2031, adopted on 26 February 2018, read with the London Plan. Its design and townscape policies sit alongside specific policies on residential extensions, householder development and conservation areas, and the common thread is that development must protect neighbours' daylight, sunlight and outlook.

The Design of Residential Extensions SPD is the document officers reach for on householder schemes. It expects extensions to respect the scale and form of the host house and sets out the 45-degree rule for side extensions and the 25-degree rule for rear projections as first checks; where a proposal crosses them, the council looks for the impact to be tested against BRE 209 (2022 edition). Sites in or beside the Sutton Garden Suburb conservation area around Benhilton attract particularly close attention to amenity. The Local Plan is at sutton.gov.uk/planning-policy and the SPDs, including the Design of Residential Extensions SPD, at sutton.gov.uk/planning-and-building/planning/planning-policy/supplementary-planning-documents.

When you need an assessment in Sutton

• Two-storey or part two-storey side extensions on the semi-detached streets of Wallington, Carshalton Beeches and Cheam, where the neighbour's flank windows are a side passage away
• Rear extensions and rear dormers in Worcester Park, North Cheam and Belmont that cross the SPD's 45-degree or 25-degree line on plan
• Flats replacing pubs, garages and redundant buildings on Cheam Common Road, the A24 and around Sutton town centre, where every new home is tested internally as well as the neighbours
• Applications heading to planning committee, where the report may be read alongside one commissioned by a neighbour
• Schemes in or beside the Sutton Garden Suburb and Carshalton Village conservation areas

How we work

You send drawings and photographs; we build the 3D model of the scheme and its neighbours ourselves. The fee is fixed and agreed up front and a report usually takes 4–5 working days, though as the examples above show we will tell you straight if a committee deadline can be met. The service is described on our daylight and sunlight assessment page. Every report covers the four BRE tests:

• VSC for daylight at each neighbouring window, with whole-room weighting where a room has more than one window
• NSL for daylight distribution within rooms
• APSH for annual and winter sunlight to windows facing within 90 degrees of south
• Sun on ground for gardens: two hours of sun on at least half the area on 21 March

The methods are on our VSC, NSL and APSH page and the benchmarks on our BRE guidelines page.

Frequently asked questions in Sutton

My neighbour's kitchen has a small side window facing my extension. Will it fall short?

On its own it may, which is why BRE 209 allows a room lit by more than one opening to be assessed as a whole. If the kitchen also has a rear window or a glazed door, the weighted result is what matters, and we always report the single-window figure alongside it so nothing is hidden.

Does Sutton ask for shadow plots on a householder application?

Not routinely, but when a report may be read by another consultant or at committee we add 21 March shadow plots and model the whole terrace, as at Longfellow Road, so the assessment cannot be criticised as incomplete.

Can you turn a report round before a committee date?

Usually, if you tell us the date when you enquire. Sandhills Road went from instruction on a Saturday to a finished report on the Sunday evening. Our normal turnaround is 4–5 working days.

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 nearer Morden or Wimbledon, our Merton page covers that borough.