Daylight Requirements in Mole Valley

View across the Surrey Hills National Landscape near Box Hill above Dorking in Mole Valley

If you are planning a rear extension in Dorking, a new dwelling in Leatherhead or Ashtead, or a conversion in one of the villages beneath the Surrey Hills, it helps to understand the daylight requirements in Mole Valley before you submit. Mole Valley District Council is the local planning authority (LPA) that determines householder and residential applications here; Surrey County Council is the upper-tier authority but does not decide these proposals. This guide sets out the adopted policies that apply, the council's stated position on daylight and sunlight, and how a technical assessment supports a sound, evidence-based decision.

Daylight requirements in Mole Valley: the policy framework

The statutory development plan for the district is the Mole Valley Local Plan 2020-2039, adopted on 15 October 2024. This is a recent, full local plan that replaced the long-standing Core Strategy (2009) and the older Local Plan saved policies, so applications are now assessed against an up-to-date suite of policies rather than legacy guidance. The plan covers the towns of Dorking and Leatherhead, the larger settlements of Ashtead, the Bookhams and Fetcham, and a substantial rural area, much of which is heavily constrained by Green Belt and the Surrey Hills National Landscape.

The policy that does most of the work on daylight, sunlight and residential amenity is Policy EN4: Character and Design. Alongside its requirements on scale, height, massing, spacing between buildings and respecting existing building lines, EN4 contains a dedicated Amenity section. It requires that the amenity of future occupiers and of residents in the surrounding area is not significantly affected, and it lists the specific ways in which amenity can be harmed. The named factors include:

Loss of sunlight, daylight, overshadowing or the need for artificial light;
Overlooking, causing a loss of privacy;
Lack of outlook or a sense of enclosure;
Unacceptable visual impact; and noise, vibration and other disturbance.

The explicit reference to "loss of sunlight, daylight, overshadowing" is significant: daylight and sunlight are named directly as material amenity considerations, not left implicit. EN4 also notes that where amenity effects can be made acceptable by mitigation, the council will seek those measures, which is exactly where a technical assessment earns its place.

Extensions, spacing and the wider design tests

For the most common application type, the householder extension, the design requirements of Policy EN4 still apply. The policy asks proposals to be of an appropriate scale, height, massing, proportion and form, to achieve appropriate spacing between buildings, and to respect existing building lines, all of which bear directly on overshadowing and loss of light to neighbours. The plan also confirms at paragraph 6.38 that all proposals, including extensions and alterations, are assessed against the policies of the plan and against relevant supplementary planning guidance on character and design.

Two further policies are worth noting. Policy H10: Standards for Accessibility, Water and Space applies the nationally described space standards to new dwellings, which is relevant to the internal daylight a new home should enjoy. Policy EN8: Landscape Character governs the Surrey Hills National Landscape, which covers a large share of the district; the council records that around 37 per cent of Mole Valley is designated National Landscape, with the familiar landmarks of Box Hill and Leith Hill. In those sensitive settings the design scrutiny is greater, although the daylight and sunlight amenity tests themselves flow from EN4.

Local guidance and validation in Mole Valley

Mole Valley supports its policies with a recently updated Design Guidance for House Extensions SPD (2025), which replaced a much older 2000 version. This supplementary planning document deals expressly with neighbourliness and explicitly lists daylight and sunlight, together with overlooking and overbearing development, among the key design issues for single-storey, two-storey, front and roof extensions. The council has also adopted a set of Design Code SPDs (2025) covering Ashtead, Bookham with Fetcham, Dorking and Leatherhead, which analyse character areas and provide further advice that case officers can apply as material considerations.

The council does not, however, publish a dedicated numerical daylight and sunlight SPD or fixed separation distances. Instead, the EN4 amenity wording is applied case by case, and the recognised national methodology supplies the objective measure. That methodology is the Building Research Establishment guidance, BRE BR 209: Site Layout Planning for Daylight and Sunlight - A Guide to Good Practice (2022 edition), read with BS EN 17037 on daylight in buildings. The National Planning Policy Framework (NPPF) supports securing a good standard of amenity for existing and future occupiers and making efficient use of land, and these national documents apply through the locally adopted Local Plan policies above.

What a daylight and sunlight assessment involves

A BRE-based assessment answers two questions: what daylight and sunlight neighbouring properties currently enjoy and how the proposal would affect them, and whether future occupiers of the new accommodation would receive adequate light. The principal tests include:

Vertical Sky Component (VSC) - skylight reaching a neighbour's window, with a guideline of 27% or no worse than 0.8 times the previous value;
Daylight distribution (the no-sky line) - how daylight is spread within a room;
Annual Probable Sunlight Hours (APSH) - sunlight to windows with a significant southerly aspect, assessed annually and over winter;
Overshadowing of gardens and amenity areas - using the sun-on-ground test at the equinox.

A clear, BRE-compliant report gives a Mole Valley case officer the evidence to apply the EN4 amenity tests with confidence, and to weigh whether mitigation could make the effects acceptable. It is particularly useful for tightly grouped plots in central Dorking and Leatherhead, sensitive village and edge-of-settlement sites within the Surrey Hills National Landscape, and two-storey or rear extensions where overshadowing of a neighbour's habitable-room windows or garden is a concern. A robust assessment does not promise consent, but it helps you design out problems early and supports a sound decision.

How Fortress Associates can help

Fortress Associates provides our daylight and sunlight report service to BRE BR 209 (2022) and BS EN 17037 for sites across Dorking, Leatherhead, Ashtead, the Bookhams and the wider Mole Valley district. We work nationwide with a typical 4 to 5 working day turnaround and ask for no advance payment. Explore our full services or contact us to discuss your project. If your scheme also needs technical drawings, we prepare Building Regulations drawings alongside the planning work. You may also find our companion guide to daylight requirements in Epsom and Ewell useful for comparison with a neighbouring Surrey authority.

Sources & further reading

daylightsunlightMole ValleyDorkingLeatherheadBRE BR 209Local Plan 2020-2039residential amenity

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