Understanding the daylight requirements in Ceredigion is essential for anyone planning a new home, an extension or a larger residential scheme across the county, from the seafront terraces of Aberystwyth to the riverside streets of Cardigan. Ceredigion County Council, as the local planning authority, assesses how a proposal affects the daylight, sunlight and privacy of neighbouring properties, as well as the standard of amenity for future occupiers. This guide explains how those expectations are framed in Ceredigion's adopted planning policy, how the council's own design guidance approaches overshadowing, and how a professional daylight and sunlight assessment can support a smoother application.
The planning framework that applies in Ceredigion
Planning decisions in Ceredigion are made under the Welsh planning system. The starting point is the adopted development plan, supported by national policy. For Ceredigion this means:
- The Ceredigion Local Development Plan 2007–2022 (LDP1), formally adopted on 25 April 2013. Although the plan period has ended, the council has confirmed that the adopted LDP retains development plan status and continues to be used to determine planning applications until a replacement plan is adopted.
- Planning Policy Wales (Edition 12, 2024) and Future Wales: The National Plan 2040, which set the national policy context for good design and placemaking.
- Relevant Technical Advice Notes (TANs) and the council's adopted Supplementary Planning Guidance.
A replacement Ceredigion LDP is in preparation, but it has not yet been adopted. Until it is, applications are assessed against the 2013 plan together with Future Wales and other material considerations. It is worth noting that the eastern fringe of the county sits close to the Cambrian Mountains, but development plan responsibilities for the principal area rest with Ceredigion County Council.
How Ceredigion's adopted policies address daylight and amenity
The adopted LDP does not set a single numerical daylight standard. Instead, the protection of light, outlook and privacy is delivered through the plan's design and amenity policies, the most relevant of which are:
- Policy DM06: High Quality Design and Placemaking – requires development to be of high quality design that creates a sense of place and respects local form, while delivering an acceptable standard of amenity.
- Policy DM09: Design and Movement – addresses the layout and arrangement of development, including the relationship between buildings.
- Policy DM10: Design and Landscaping – deals with landscaping, which the council recognises can help mitigate overlooking and soften the impact of new built form.
These policies work together to ensure that new development does not unacceptably harm the living conditions of neighbours through loss of light, overshadowing or loss of privacy, and that new homes themselves enjoy good levels of natural light.
The Built Environment and Design SPG
The most useful local document for daylight matters is the council's Built Environment and Design Supplementary Planning Guidance, dated January 2015. It provides the practical detail that the LDP policies leave open, and it is the document most likely to be referenced when an officer assesses light and amenity impacts. Two parts are particularly important.
The 45-degree rule. The SPG explains that, to protect neighbouring dwellings from overshadowing or obstruction, the council applies the 45-degree rule. As the guidance puts it:
"This involves drawing a line from the mid-point of the sill of a window which is potentially affected by a neighbour's extension, at an angle of 45 degrees towards the extension. If the proposed extension crosses that line it is unlikely to be acceptable as it will cause overshadowing."
The SPG also notes that each case is judged on its merits and that there may be circumstances – most commonly with semi-detached or terraced dwellings – where a scheme that breaches the line can still be acceptable.
Separation distances. For new residential layouts, the SPG sets out the following guide measurements to provide adequate amenity space and prevent overlooking:
- a 21 metre gap between opposing windows of habitable rooms;
- a 10.5 metre gap between main windows and a blank wall; and
- a 10 metre garden depth.
The guidance adds that these distances may be reduced where a landscaping scheme helps prevent overlooking and where open space is otherwise provided. For loft conversions and dormers, the SPG encourages rooflights on rear elevations and obscure or high-level glazing where overlooking is a concern – a reminder that daylight to new accommodation must be balanced against the privacy of neighbours.
Where BRE BR 209 and BS EN 17037 fit in
Ceredigion's policies and guidance describe the principles – protecting light, avoiding overshadowing and securing privacy – but they do not in themselves provide a calculation method. Where a proposal is more sensitive (for example a flatted scheme, a backland plot in Aberystwyth, or an extension close to a neighbour's principal windows), the recognised national best-practice methodology is the Building Research Establishment guide Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice (BRE BR 209, 2022 edition), alongside the daylight provisions of BS EN 17037.
These documents provide the numerical tests that planning officers and inspectors are familiar with, including:
- Vertical Sky Component (VSC) – the daylight reaching a neighbouring window, with the well-known 27% benchmark and the guidance that a reduction to less than 0.8 times the former value is likely to be noticeable;
- No Sky Line / daylight distribution – how far daylight penetrates into a room;
- Annual Probable Sunlight Hours (APSH) – the sunlight received, particularly relevant for south-facing windows and gardens.
A BRE-based report translates the 45-degree rule and the SPG's qualitative aims into measurable figures, which is often the most persuasive way to demonstrate that a scheme complies with Policy DM06 and the wider design objectives.
Practical tips for Ceredigion applicants
- Read the SPG early. Sketching the 45-degree line and checking the 21m / 10.5m / 10m separation guides before you finalise a design can save a costly redesign later.
- Think about orientation. Ceredigion's coastal and valley settings mean aspect and topography matter; the SPG's passive design section encourages maximising natural daylight in new homes.
- Engage neighbours. The council explicitly advises discussing proposals with neighbours at an early stage, particularly for extensions sited close to adjacent dwellings.
- Commission a report where impact is likely. If your scheme is close to neighbouring windows or involves additional height, a daylight and sunlight assessment provides the evidence officers expect.
How Fortress Associates can help
Fortress Associates provides our daylight and sunlight report service for projects across Ceredigion and the rest of the UK. We prepare assessments to BRE BR 209 (2022) and BS EN 17037, presented clearly for submission to Ceredigion County Council, and we can also produce Building Regulations drawings for the same project. We work to a 4–5 working day turnaround and ask for no advance payment. To discuss your scheme, get in touch and we will advise on exactly what is needed.
Sources & further reading
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