If you are planning a house extension in Clitheroe, a new dwelling in Longridge or Whalley, or a conversion in one of the villages of the Forest of Bowland, it pays to understand the daylight requirements in Ribble Valley before you submit. Ribble Valley Borough Council is the local planning authority (LPA) for the area; Lancashire County Council is the upper-tier authority but does not determine householder or residential planning applications here. This guide sets out which adopted policies apply, the council's stated position on daylight and privacy, and how a technical assessment supports a sound decision.
Daylight requirements in Ribble Valley: the policy framework
The statutory development plan for the borough is the Ribble Valley Core Strategy 2008-2028: A Local Plan for Ribble Valley, adopted in December 2014. Unusually among Lancashire districts, this single Core Strategy contains both the strategic vision and the detailed development management policies against which day-to-day applications are judged. The council is preparing a new single Local Plan to take the borough to 2038, which will eventually consolidate the Core Strategy and the Housing and Economic Development DPD; until that plan is adopted, the 2014 Core Strategy remains the primary policy document.
The policy that does most of the work on daylight, sunlight and amenity is Policy DMG1: General Considerations. It applies to all development and groups its requirements under Design, Access, Amenity and Environment headings. The Amenity section is the relevant part for daylight and sunlight, and it requires that all development must:
- Not adversely affect the amenities of the surrounding area;
- Provide adequate day lighting and privacy distances;
- Have regard to public safety and Secured by Design principles; and
- Consider air quality and mitigate adverse impacts where possible.
The explicit reference to "adequate day lighting and privacy distances" is significant: daylight is named directly as a development management consideration rather than being left implicit. The Design section of the same policy reinforces this by requiring proposals to consider density, layout and the relationship between buildings, and to be sympathetic in scale and massing, both of which bear directly on overshadowing and loss of light.
Extensions and the wider amenity tests
For the most common type of application, the householder extension, Policy DMH5: Residential and Curtilage Extensions states plainly that proposals to extend or alter existing residential properties must accord with Policy DMG1 and any relevant designations affecting the site. In practice this means that a rear or two-storey side extension in Clitheroe or Whalley is tested for its impact on neighbouring daylight, sunlight and privacy through the DMG1 amenity requirements. A large part of the borough also lies within the Forest of Bowland National Landscape (the designated Area of Outstanding Natural Beauty), where Policy DME2 on landscape and townscape protection adds a further layer of design scrutiny, though the daylight and privacy tests themselves still flow from DMG1.
Local guidance and validation in Ribble Valley
Ribble Valley does not publish a dedicated daylight and sunlight Supplementary Planning Document, nor does it set out fixed numerical separation distances in the way some neighbouring authorities do. Instead, the phrase "adequate day lighting and privacy distances" in Policy DMG1 is applied case by case, having regard to the character of the area. The council operates a Local Validation Checklist for Planning Applications (the current version adopted on 29 May 2025), which sets out the supporting information expected with an application; where a proposal raises a credible risk of harm to a neighbour's daylight or sunlight, a technical assessment is the most reliable way to demonstrate that the DMG1 amenity tests are met.
Because the Core Strategy uses qualitative language, the recognised national methodology provides 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 Core Strategy 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 Ribble Valley case officer the evidence to apply the "adequate day lighting and privacy distances" requirement of Policy DMG1 with confidence. It is particularly useful for tightly grouped properties in central Clitheroe, sensitive village settings within the Forest of Bowland, and 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, evidence-based 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 Clitheroe, Longridge, Whalley and the wider Ribble Valley. 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 Lancaster useful for comparison.
Sources & further reading
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