Daylight and Sunlight Reports in Wandsworth

A daylight and sunlight report is a technical study that measures how much natural light a building — yours, and your neighbours' — receives, and how a proposed development changes it. It does two related jobs. The first is amenity to neighbours: it quantifies whether your extension, new house or block of flats reduces the daylight and sunlight reaching the windows and gardens of the surrounding properties, and by how much. The second is amenity within the proposal itself: it checks that the new homes you are creating will themselves enjoy adequate daylight and sunlight, so you are not building sub-standard accommodation. On most residential schemes in Wandsworth the neighbour question is the one that drives the outcome, but on new-build houses and flats both matter.

The report is prepared by modelling the site in three dimensions — the existing buildings around it, the ground levels, the neighbouring windows, and the proposed development — and then running the standard BRE calculations for each affected window and each area of garden. The results are expressed as numbers (percentages of sky visible, percentages of annual sunlight hours, areas of a room that can see the sky) and compared against the BRE target values and, crucially, against the 'before and after' position: the question is usually not whether a neighbour's window is perfectly lit in absolute terms, but whether your proposal materially worsens it relative to what it had before.

It is important to understand what the report is not. It is not a legal right-to-light study — that is a separate, private-law matter about easements and injunctions, assessed on a different basis (the Waldram method and the '50/50 rule') and dealt with by rights-of-light surveyors and solicitors, not by the planning system. A planning daylight and sunlight report is about the public planning interest in amenity, measured against BRE guidance. The two overlap in the geometry they analyse but serve different purposes, and having a planning report that passes does not, by itself, resolve any private right-to-light exposure. We will flag where a scheme may raise right-to-light issues so you can take the right advice, but the report itself addresses the planning tests.

Finally, the report is best understood as evidence in a balancing exercise rather than a pass-or-fail exam. BRE guidance is explicit that its target values are guidelines, not mandatory limits, and that they should be applied flexibly with regard to context — a dense urban borough like Wandsworth cannot reasonably be held to the same absolute light levels as a suburban cul-de-sac. Where a proposal fully meets the BRE targets, the report demonstrates compliance and largely removes light as an objection. Where it falls short in places, a good report explains the extent and significance of the shortfall, sets it in its urban context, and helps the case officer and members reach a reasoned judgement rather than a knee-jerk refusal.

Not every application needs a daylight and sunlight report, and Wandsworth's own validation guidance is clear that it will only ask for supporting documents where they are proportionate to the nature, scale and location of the development and are relevant, necessary and material to the decision. A modest single-storey rear extension on a generous plot with distant neighbours will rarely need a formal report. But a great many Wandsworth schemes do, and the borough's local validation checklist lists contextualised daylight and sunlight information among the documents that may be required. The trigger is essentially about impact: the closer, taller and bulkier your proposal is relative to neighbouring windows and gardens, the more likely a report will be needed.

In practice, the schemes that most often require a report in Wandsworth are: two-storey and larger rear or side extensions close to a boundary and facing a neighbour's habitable-room windows; roof extensions, mansards and additional storeys that raise the height of a terrace or block; new dwellings on backland and garden plots that sit behind or beside existing houses; replacement dwellings that are significantly taller or bulkier than the house they replace; and blocks of flats, which almost always need a full assessment both for neighbour impact and for the light within the new units. Corner sites, plots on the north side of a neighbour, and anything overlooking a small enclosed garden are all higher-risk for light and more likely to attract a request.

There are three routes by which the requirement arises. It can be flagged at pre-application, where the council's officers advise that daylight and sunlight will be a key consideration and should be addressed up front. It can be a validation requirement, where the case officer will not register the application until the report is supplied. Or it can arise during determination, where neighbours object on light grounds or the officer decides the impact needs quantifying, and the council requests the report before it will decide — which delays the decision and puts you on the back foot. The best position is always to have anticipated it and either included the report or designed demonstrably within the guidelines from the start.

Because the requirement is judgement-based, the safest approach is to assess the light risk of your scheme at the outset rather than wait to be asked. On many Wandsworth extensions a quick screening — checking the proposal against the 45° and 25° rules of thumb — will show either that light is plainly not an issue (so no report is needed) or that it is close to the line (so a full report is worth preparing pre-emptively). We carry out that screening as part of feasibility, so you know early whether a report is likely to be required and can budget and design accordingly, rather than discovering it when the application is already in.

Wandsworth is a large south-west London borough stretching from the Thames at Battersea, Nine Elms and Wandsworth Town down through Clapham, Balham, Tooting, Earlsfield, Putney, Southfields and Roehampton. It takes its name from the River Wandle, which rises from chalk springs below the North Downs and meanders north to join the tidal Thames at Wandsworth, and which once powered one of the most concentrated industrial areas in the country — mills, breweries and factories lined the Wandle and the riverside. That industrial past is why the borough today has so much former commercial and riverside land being redeveloped, and why its residential streets are so densely packed: the terraces were built to house a large working population close to the works, and they were built close together.

That density is the root of why daylight and sunlight is so contested in Wandsworth. Long runs of two- and three-storey Victorian and Edwardian terraces with narrow rear gardens, closely spaced mansion blocks in Battersea and Putney, and tight infill and backland plots mean that almost any addition has a neighbour nearby whose light it could affect. A rear extension reaches towards the next-door garden and the neighbour's rear windows; a mansard raises the ridge over the whole terrace; a new house in a back garden sits within metres of the boundaries on several sides. In a borough where gardens are small and prized, the loss of afternoon sun to a patio or the darkening of a kitchen window is felt keenly, and neighbours object to it — which is exactly why the council wants the impact measured rather than argued.

The borough is also exceptionally rich in heritage, with forty-six conservation areas ranging from single streets to very large areas such as West Putney, alongside the remains of old villages like Battersea Square and the internationally significant post-war modernism of the Alton Estate in Roehampton. Conservation-area character and the setting of listed buildings add another layer: a scheme may need to be lower or set further back not only to protect a neighbour's light but to respect the townscape, and the two considerations often push in the same direction. On the other side of the ledger, Wandsworth contains some of the largest new development in London at Nine Elms and around the restored Battersea Power Station, where tall buildings and daylight/sunlight assessments of both the new homes and their neighbours are a routine and central part of the planning process.

Water and topography matter too. Parts of the borough are low-lying and at risk of flooding from the Wandle, the Thames, Beverley Brook and the Graveney, and the Wandle valley and riverside have their own character. None of this changes the daylight and sunlight tests themselves, but it shapes the wider set of supporting documents a Wandsworth application often needs — flood risk, heritage, arboricultural — of which the daylight and sunlight report is one. The practical point for anyone building here is that Wandsworth's combination of high demand, tight plots, small gardens and strong amenity and design policies makes light one of the most common battlegrounds in the borough, and a well-prepared report one of the most useful things you can put in front of a case officer.

Wandsworth adopted its current Local Plan on 19 July 2023, covering the period to 2038, and this — together with the London Plan and the National Planning Policy Framework — is the development plan against which applications are decided. Daylight and sunlight sits within the plan's approach to design and amenity. The plan's design and housing policies require development to achieve a high standard of design and a good standard of amenity for both existing and future occupiers, and that expressly includes protecting the daylight and sunlight of neighbouring properties and providing adequate daylight within new homes.

Housing standards are dealt with under Policy LP27, which requires residential development to meet defined housing standards including private internal space and levels of daylight and sunlight for the new homes created. In other words, the plan does not only look outward at the impact on neighbours; it also requires that the dwellings you build enjoy adequate light themselves, so that daylight and sunlight is assessed on both sides of the boundary. Alongside LP27, the plan's overarching design policies (including LP1 and LP2) set the expectation that development responds to context and delivers good amenity, and the borough continues to rely on the detailed design and amenity policies carried through from its Development Management Policies Document, originally adopted in 2016, which set out specific considerations on residential amenity, outlook, privacy and light.

The methodology the council uses to judge those policies is the BRE guidance. Wandsworth's local validation checklist (in its published local planning application requirements, updated in December 2023) refers to contextualised daylight and sunlight plans and assessments, and the BRE document 'Site Layout Planning for Daylight and Sunlight: a guide to good practice' is the recognised standard the borough and its consultants apply when assessing developments for access to daylight and sunlight. So the policy sets the objective — protect neighbours' amenity and provide good light in new homes — and the BRE tests provide the measurable yardstick against which a proposal is judged.

Two practical points follow. First, because the target values are BRE guidelines applied with regard to context, Wandsworth's decisions turn on judgement, not arithmetic alone: a scheme that misses a target on one or two windows in a dense street may still be acceptable, while a scheme that harms light more widely may be refused even if some windows pass. A report that engages honestly with that judgement — explaining significance and context — is far more persuasive than one that simply lists numbers. Second, the policies apply to future occupiers as well as neighbours, so on new houses and flats we assess the light within the proposal from the outset, because a scheme that harms nobody's light but creates dark rooms of its own can still fail LP27. We would only cite specific figures and thresholds where they can be verified against the adopted plan and the current validation guidance; where a precise local figure is not published, the assessment relies on the national BRE standard, which is what the borough itself applies.

The technical foundation of every planning daylight and sunlight report in England is the Building Research Establishment's report BR 209, 'Site Layout Planning for Daylight and Sunlight: a guide to good practice'. First published decades ago and now in its third edition (2022), it is the document that planning authorities, including all the London boroughs, treat as the standard methodology for assessing access to daylight and sunlight. It is guidance rather than statute — BR 209 itself stresses that its numerical targets are advisory and should be applied flexibly — but in practice it is the yardstick, and a report that departs from its methods needs to justify why.

BR 209 provides distinct tests for four things: daylight to existing neighbouring windows (measured mainly by the vertical sky component, VSC, backed up by the no-sky-line); sunlight to existing neighbouring windows (measured by annual probable sunlight hours, APSH); daylight and sunlight within proposed new dwellings; and sunlight to gardens and amenity spaces (the two-hours-of-sun overshadowing test). It also contains the simplified rules of thumb — the 25° line for daylight and the 45° rule for domestic extensions — that allow a quick screening before the full calculations. The sections that follow explain each of these in plain English.

The important framing is that most tests are comparative. For existing neighbours, the assessment almost always compares the 'before' situation (what the window or garden enjoys today) with the 'after' situation (what it will enjoy once your scheme is built), and BRE sets a proportional threshold: a reduction is generally regarded as noticeable and potentially unacceptable once the retained value falls below 0.8 — that is, below 80% of the former figure. So a window keeping, say, 85% of its former daylight would generally be within guidelines, while one dropping to 70% would not, and the report would then consider how significant that is in context.

The 2022 edition made real changes, which matter when you commission a report today: the way daylight inside new homes is assessed moved away from the old average daylight factor towards the metrics and target illuminance values of the European daylight standard BS EN 17037 (assessed by the proportion of a room achieving target daylight); the sunlight test for new rooms shifted to checking sunlight on a date in the late-winter/early-spring window rather than the old annual-hours approach; and trees — both existing and proposed — are now to be included in the modelling. For assessing impact on existing neighbours, the familiar VSC, NSL and APSH tests remain the core of the work. A competent report uses the current edition and the current metrics; using out-of-date methods is a needless way to undermine your own evidence.

The vertical sky component is the headline daylight measure for existing neighbouring windows, and the one most often quoted in reports and objections. VSC is the amount of sky visible from a point at the centre of a window, on its outside face, expressed as a percentage of the light available from an unobstructed sky. Put simply, it measures how much sky a window can 'see': a window with a clear view of the sky has a high VSC, while one that faces a wall or a tall extension close by has a low VSC. Because it is measured on the outside of the window, VSC depends only on the massing of the surrounding buildings and obstructions, not on the room behind — which makes it a clean, repeatable measure of the effect of a proposal on a neighbour.

The BRE target is a VSC of 27% or more. A window that enjoys at least 27% VSC is regarded as receiving good daylight, and a completely unobstructed vertical window has a VSC of just under 40%. Where a proposal reduces a neighbour's VSC, the key test is proportional: if the VSC after development is still 27% or more, daylight is generally fine; if it is below 27%, the window should retain at least 0.8 times — 80% of — its former value for the loss to be within guidelines. So a window that drops from 30% to 25% (a retained ratio of 0.83) is generally acceptable even though it is now below 27%, whereas one that drops from 30% to 20% (a ratio of 0.67) shows a noticeable loss that the report must then assess for significance.

This proportional 0.8 rule is central to how Wandsworth schemes are judged, because in a dense borough many windows already sit below 27% before anything is built — they face a terrace, a boundary wall or a mansion block across a narrow gap. In that context the absolute 27% target is often unachievable and the real question is whether the proposal makes a materially worse difference, which the 0.8 ratio captures. A well-prepared report leads with the retained ratios for each affected window, not just the raw figures, so the case officer can see immediately which windows are within guidelines and which are not.

VSC is closely related to the 25° rule of thumb. BRE notes that a VSC of around 27% corresponds broadly to an obstruction subtending an angle of about 25° above the horizontal, measured from the centre of the lowest window. That is why the 25° line is used as a quick screen: if the proposed building, seen in section from a neighbour's lowest window, stays below a line drawn upward at 25°, daylight is unlikely to be a problem and a full VSC calculation may not be needed; if it rises above that line, a proper VSC assessment is warranted. We use the 25° line at feasibility to decide whether a full report is needed and, if it is, to guide how the massing can be adjusted to pass.

The vertical sky component tells you how much sky a window can see, but not how the daylight is distributed inside the room behind it. That is what the no-sky-line does. The no-sky-line — sometimes called the daylight distribution test — is the line drawn on the working plane inside a room (taken at 0.85 metres above the floor, roughly table height) that separates the part of the room that can still see some sky through the windows from the part that cannot. Everything on the window side of the line receives direct skylight; everything beyond it is in the zone that no longer sees the sky and so feels gloomy even in the daytime. The test measures the area of the room that still receives direct skylight.

As with VSC, the no-sky-line test on existing neighbours is comparative. If a proposal causes the area of a neighbour's room that can see the sky to shrink so that it retains less than 0.8 — 80% — of its former sky-lit area, the loss of daylight distribution is likely to be noticeable and outside the BRE guidelines. In practice this matters most for deep rooms and for windows that are being partly blocked from the side or above: a large rear extension can leave the front half of a neighbour's through-lounge in permanent shade even if the VSC to the window itself is not dramatically reduced, and the no-sky-line is the test that captures that.

The no-sky-line requires knowledge of the room layout behind the affected window — its depth and the position of windows — which is not always available for neighbouring properties. Where the internal layout can be established (from survey, from published plans of similar house types, or from reasonable assumptions clearly stated), we include the no-sky-line analysis for the rooms most at risk. Where it cannot be established, the report relies on VSC as the primary daylight measure and says so, which is standard and accepted practice. For the light within a proposed new dwelling, the internal layout is of course known, and daylight distribution is assessed directly.

Reading VSC and NSL together gives the full daylight picture: VSC shows how much light reaches the window, NSL shows how far that light penetrates into the room. A scheme that passes VSC but fails NSL, or vice versa, is not uncommon, and Wandsworth officers will look at both. A report that presents them side by side, room by room, is far more useful than one that leans on a single number.

Daylight (diffuse light from the whole sky) and sunlight (direct rays from the sun) are assessed separately, because they behave differently. The BRE sunlight test for existing neighbouring windows is annual probable sunlight hours, or APSH. It measures the proportion of the sun's annual track across the sky that can actually reach a given window, taking account of the obstructions in front of it — expressed as a percentage of the total probable sunlight hours in a year for the location. Because the sun in the northern hemisphere is always in the southern half of the sky, the sunlight test only applies to windows that face within 90° of due south; a window facing due north can never receive direct sun, so APSH is not assessed for it.

The BRE targets are that a relevant window should receive at least 25% of annual probable sunlight hours, of which at least 5% should fall in the winter months (the period from 21 September to 21 March). Winter sun is singled out because it is the scarcest and most valued — a room that gets sun in high summer but is in permanent shade all winter is poorly served — so the test protects both the annual total and a minimum winter share. As with daylight, where a proposal reduces a neighbour's sunlight, the loss is generally within guidelines if the window still meets those targets, or if it retains at least 0.8 — 80% — of its former annual and winter sunlight; a drop below that proportional threshold is regarded as a noticeable loss.

In Wandsworth's terraced streets, orientation is everything for sunlight. A rear extension that projects towards a neighbour whose main windows face south or west can take away exactly the afternoon and evening sun that a rear garden and kitchen rely on, which is why sunlight objections are common on the south side of any proposal. Conversely, a scheme to the north of its neighbours may have little or no sunlight impact at all, because the neighbours' sunny aspect is away from the development. The APSH analysis, mapped window by window with the retained ratios, shows precisely where sunlight is affected and where it is not, which is often decisive in resolving a neighbour's objection.

For the proposed dwellings themselves, the 2022 BRE edition changed the sunlight test: rather than the old annual-hours measure, sunlight to new habitable rooms is now checked on a date in the late-winter to early-spring window, with the guidance treating a living room that receives sun as the priority and generally regarding a dwelling as satisfactory where at least one of its main rooms (preferably the living room) receives adequate sunlight. We apply the current method for new units and the established APSH test for existing neighbours, and we are explicit in the report about which test applies to which window.

Light to windows is only part of the picture; BRE also assesses sunlight to gardens and amenity areas, because a shaded garden is a real loss of amenity even if the windows behind it are fine. This is the overshadowing test. The BRE recommendation is that at least half of a garden or amenity area should receive at least two hours of direct sunlight on 21 March — the spring equinox, chosen because it represents average conditions midway between the extremes of summer and winter. A space that meets that standard is regarded as adequately sunlit; one that does not is overshadowed.

For existing neighbouring gardens, the test is again comparative: if a proposal reduces the sunlit area (the part receiving two hours of sun on 21 March) to less than 0.8 — 80% — of its former extent, or takes it below the half-the-area threshold where it was above it before, the loss of amenity is regarded as significant. This is a frequent issue in Wandsworth, where rear gardens are small: a two-storey rear extension or a tall new house on the south side of a neighbour's garden can plunge a large part of that garden into afternoon shade, and the overshadowing analysis quantifies exactly how much.

The overshadowing assessment is usually presented as shadow plots — 'before and after' plans and, for larger schemes, a series of hourly shadow diagrams through the day (transient overshadowing) that show how the shadow of the proposal moves across neighbouring gardens over the course of 21 March. These diagrams are among the most persuasive parts of a report because they are visual and intuitive: a case officer, a planning committee or a concerned neighbour can see at a glance whether a garden is thrown into shade or barely affected. Where the impact is modest, the shadow plots are often the single most reassuring piece of evidence in the whole application.

As with all the BRE tests, the overshadowing standard is applied with regard to context. In a dense inner-London setting some existing gardens are already heavily shaded by surrounding buildings, and the realistic question is whether the proposal makes a material difference rather than whether the garden meets an absolute ideal. A good report sets the garden's existing condition alongside the proposed condition, so the true effect of the scheme — not the pre-existing constraint — is what the decision turns on.

Before the full calculations, BR 209 offers two simplified rules of thumb that are invaluable for screening a scheme early — and that Wandsworth officers themselves use as first checks on householder applications. The first is the 45° rule, which is used mainly for domestic extensions. It is applied in two planes. In plan, a 45° line is drawn from the centre of the nearest habitable-room window on the neighbouring property; in section (elevation), a 45° line is drawn upward from the same window. If the proposed extension crosses both of those 45° lines, it is likely to cause a material loss of daylight to that window and a full assessment is warranted; if it stays clear of them, daylight loss is usually acceptable.

The second is the 25° line, which relates directly to the VSC target. Drawn in section from the centre of the lowest affected window on the neighbouring property, a line rising at 25° above the horizontal represents, roughly, the obstruction angle that corresponds to the 27% VSC target. If the proposed building stays below that 25° line, the window is likely to retain good daylight and detailed VSC calculations may be unnecessary; if the proposal rises above the line, a full VSC assessment is needed. The 25° line is the quick way to answer the question 'is this tall enough, close enough, to be a daylight problem?' before committing to the full modelling.

These rules are screening tools, not a substitute for the full report where impact is real. The 45° rule in particular is designed for the common domestic case — a rear or side extension next to a neighbour's perpendicular window — and it can be conservative or generous depending on geometry, so passing it is reassuring but not conclusive, and failing it means a proper VSC/APSH assessment is needed rather than that the scheme is automatically unacceptable. We use both rules at the feasibility stage of every Wandsworth extension to decide, quickly and cheaply, whether a full report is required and how the design should be shaped to keep within the guidelines.

Using the rules of thumb well is often what allows a scheme to avoid needing a full report at all. If we can show, on a section, that a rear extension sits comfortably below the neighbour's 45° and 25° lines, that is frequently enough to satisfy a householder case officer that daylight is not an issue, saving the cost and time of a full assessment. Where the geometry is tighter, the rules tell us exactly how much to pull the design back — the projection, the height, the set-off from the boundary — to bring it within the lines. Either way, the screening is what turns daylight from a late-stage risk into an early-stage design parameter.

A daylight and sunlight report that will actually help your Wandsworth application is a structured technical document, not a paragraph of reassurance. It should open with an introduction that identifies the site, the proposal and the surrounding properties assessed, and states the methodology — that the assessment follows BRE BR 209 (2022) — and the software and modelling assumptions used. It should describe the existing situation: the neighbouring buildings, the relevant windows and rooms, the gardens and amenity areas, and the site levels, all captured from a measured survey and, where necessary, from published or reasonably assumed internal layouts, with those assumptions stated openly.

The core of the report is the results, presented test by test and property by property. For each affected neighbouring window it should give the daylight results (VSC, and NSL where the layout allows) as 'before' and 'after' figures with the retained ratio against the 0.8 threshold; and, for windows within 90° of south, the sunlight results (APSH annual and winter) on the same basis. For gardens and amenity spaces it should give the overshadowing results with 'before and after' sunlit areas and shadow plots. Where the proposal creates new homes, the report should also assess the daylight and sunlight within those units against the current BRE/BS EN 17037 targets, so LP27 is addressed. Clear tables and annotated plans matter here: a case officer needs to see at a glance which windows pass and which do not.

Crucially, the report should not stop at the numbers. It must interpret them: which losses are within BRE guidelines and which are not; for those that are not, how significant the loss is (a small drop across a couple of windows in a dense street is a very different thing from a large reduction across many rooms); and how the results should be read in the context of the site's urban density and the existing baseline. This narrative — the professional judgement that turns figures into a planning case — is what distinguishes a report that persuades from one that merely reports. It should conclude with a clear summary of compliance and, where relevant, of why any shortfalls are acceptable in context.

Finally, the report should be honest and defensible. Overstating compliance or quietly omitting an affected window will be found out — by an objecting neighbour's own surveyor, or by the officer — and destroys the credibility of the whole document. A report that squarely acknowledges the windows that fall short, and makes the reasoned case for why the scheme is nonetheless acceptable, is far stronger in front of a case officer or a committee than one that pretends there is no impact. That combination of technical rigour and candid, context-aware judgement is the standard we work to.

We start with the survey and the model. An accurate daylight and sunlight report depends on an accurate three-dimensional model of the site and its surroundings — the neighbouring buildings, their window positions, the ground levels and any relevant obstructions such as boundary walls and significant trees, which the 2022 guidance now expects to be included. We build that model from measured survey information, from your proposed drawings, and from available data on the neighbouring properties, and we are explicit about where we have had to make reasonable assumptions (for example about a neighbour's internal room layout that we cannot see).

We then run the BRE tests — VSC and NSL for daylight, APSH for sunlight, and the overshadowing analysis for gardens — for every affected window and amenity area, in the 'before and after' comparison that the guidance requires, and, for new dwellings, assess the light within the proposal against the current targets. Because we are architects as well as assessors, we do this iteratively: if the first run shows a window or a garden falling below the 0.8 threshold, we can adjust the design — pull back the projection, lower the ridge, set the massing off the boundary, reshape the roof — and re-run the test, so the scheme that goes forward is one shaped to pass rather than one merely measured after the fact.

This is the real advantage of having the assessment done by the team that is also designing the building. A standalone surveyor can tell you your scheme fails; they cannot redesign it for you. Because Crown produces the architecture and the daylight and sunlight analysis together, the feedback loop is immediate and the design and the light case move forward as one. Time and again, an early assessment turns a scheme that would have attracted a light objection into one that sits within the guidelines, at no loss to the accommodation that actually matters.

Finally, we write the report for its audience — the Wandsworth case officer and, where a scheme goes to committee, the members and the public — with clear tables, annotated plans, shadow diagrams and a narrative that ties the results to the borough's amenity and housing-standards policies. And because the report is one document among several the application needs, we coordinate it with the design and access statement, the drawings and any other supporting studies so the whole submission tells a single, consistent story. The result is a report that does not just satisfy validation but actively helps to win the permission.

A daylight and sunlight report rarely travels alone. On a Wandsworth application it sits within a package of drawings and supporting documents, and it is strongest when it is consistent with the rest of them. The existing and proposed drawings define the massing that the report assesses, so the two must match exactly — a common failing is a report modelled on a slightly different scheme from the one submitted, which an objector or officer will spot. The design and access statement, where one is required, should reference the daylight and sunlight findings as part of its account of how the scheme responds to context and protects amenity.

For larger residential schemes, the report interacts with the housing-standards case: Policy LP27 requires both adequate internal space and adequate daylight in the new homes, so the daylight and sunlight assessment of the proposed units and the accommodation schedule need to align. On sensitive sites the report may sit alongside a heritage statement (where conservation-area character or a listed building's setting is engaged), a tree survey (relevant because trees now feature in the daylight modelling and because their retention affects both light and layout), and, on low-lying sites near the Wandle or the Thames, a flood risk assessment. None of these changes the daylight tests, but a coordinated set of documents that do not contradict each other is far more convincing than a pile of separately authored studies.

The report also has a role in managing neighbour relations, which in Wandsworth's tight streets can make or break an application. Neighbour objections on light grounds are among the most common the borough receives, and a clear, honest report — especially its shadow diagrams — can pre-empt or answer those objections directly. Where we can show a neighbour, in advance, that their windows and garden are barely affected, an objection may never be lodged; where there is a real but modest impact, the report gives the officer the evidence to conclude it is acceptable rather than being swayed by an unquantified complaint.

In short, the daylight and sunlight report is one strand of a coherent application, and its value is multiplied when it is prepared as part of the whole rather than commissioned in isolation. That is how we approach it: as the piece of technical evidence that supports the design story the rest of the submission is telling, prepared and coordinated by the team responsible for the scheme as a whole.

The most common and most avoidable mistake is leaving daylight and sunlight to the end. A scheme designed to the client's brief without regard to the neighbours' light, then assessed only when the application is being assembled, frequently turns out to breach the guidelines — and by then the choice is a hard one: submit and risk refusal, or redesign at cost and delay. Assessing early avoids that trap entirely. The second common mistake is not commissioning a report at all where one is plainly needed, and being caught out mid-application when the officer or a neighbour raises light: the council then requests the report, the clock stops, and the applicant scrambles to produce under pressure the very evidence that should have been in from the start.

On the technical side, mistakes include modelling the wrong scheme (a report that does not match the submitted drawings), omitting affected windows or gardens (which undermines credibility the moment they are noticed), ignoring the internal-layout dimension so that only VSC is reported when the no-sky-line is the real issue, and using out-of-date methods — reporting internal daylight by the superseded average-daylight-factor approach, or forgetting that trees now belong in the model. Each of these gives an objector or officer an easy reason to discount the report, which is the opposite of what you are paying for.

A subtler failing is a report that gives numbers but no judgement. In a dense borough like Wandsworth, some breaches of the absolute targets are inevitable and acceptable; a report that simply lists them without explaining their significance and context invites the officer to treat every shortfall as harm. Conversely, a report that overstates compliance and glosses over real losses will be exposed and will taint the whole application. The reports that succeed are candid about the impacts and make the reasoned, context-aware case for why the scheme is nonetheless acceptable.

Finally, applicants sometimes conflate the planning report with a right-to-light position, and are surprised later by a neighbour's private claim. The planning report addresses the council's amenity tests; it does not resolve private easements of light, which are a separate legal matter. Where a scheme has right-to-light exposure — typically taller development close to long-established neighbouring windows — we flag it so you can take specialist advice early, rather than discovering it after permission is granted. Avoiding all of these pitfalls comes down to the same discipline: assess early, model the actual scheme accurately and completely, use the current methods, judge honestly, and coordinate the report with the rest of the application.

A daylight and sunlight report is one of a family of technical documents a Wandsworth residential application may need, and understanding how it relates to the others helps you plan the whole submission. The design and access statement is the narrative document that explains the design and how it responds to context and amenity; on schemes where a DAS is required it should draw on the daylight and sunlight findings. The drawings — existing and proposed plans, elevations and sections — are the basis the daylight report models, and must be identical to the version submitted.

Where the site is in one of Wandsworth's forty-six conservation areas or affects a listed building or its setting, a heritage statement will be needed, and its conclusions on scale and massing often sit alongside the daylight case, because a scheme kept lower or set further back to protect a neighbour's light is frequently also the one that respects the townscape. An arboricultural (tree) survey is relevant not only in its own right but because trees now form part of the daylight and sunlight model under the 2022 guidance, and their retention shapes both light and layout. On the borough's low-lying land near the Wandle, the Thames, Beverley Brook or the Graveney, a flood risk assessment may be required. Larger schemes may also need transport, air quality, noise or energy statements.

For new homes, the daylight and sunlight report connects directly to the housing-standards evidence: the accommodation schedule and space-standard compliance under Policy LP27 go hand in hand with the assessment of daylight within the units, because the plan requires both. Getting these documents to agree with one another — same scheme, same numbers, same story — is a large part of a smooth validation and a persuasive application, and it is much easier when they are produced or coordinated by one team.

We prepare and coordinate the full set of documents a Wandsworth application needs, so the daylight and sunlight report is not an orphan study but an integrated part of a coherent submission. If your scheme needs only a daylight and sunlight report and drawings, that is what we do; if it needs the wider package, we assemble it, keeping every document consistent with the design and with each other.

The cost of a daylight and sunlight report depends chiefly on the complexity of the assessment: how many neighbouring properties and windows are affected, whether the internal no-sky-line analysis is required, whether gardens need overshadowing and transient-shadow diagrams, and whether the light within proposed new homes must be assessed as well as the impact on neighbours. A straightforward screening for a modest householder extension — checking a scheme against the 45° and 25° rules on a section — is a small piece of work and may show that no full report is needed at all. A full BRE assessment of a scheme affecting several neighbours, or a block of flats requiring both neighbour and internal analysis, is a larger commission.

It is worth being clear-eyed about the economics. Set against the cost of a refused application — the wasted planning fee, the professional time, the months of delay, and the redesign needed to try again — a daylight and sunlight report is inexpensive, and an early assessment that shapes the design to pass is cheaper still, because it avoids the abortive work altogether. On schemes where light is genuinely a risk, the report is one of the highest-value pieces of the whole application; skimping on it to save a modest sum is a false economy if it leads to refusal.

There are the usual application costs to factor in alongside the report: the council's planning application fee (set nationally and depending on the type and scale of the proposal), and, where the officer advises it, the cost of Wandsworth's pre-application service, which can be well worth it on a scheme where light is likely to be contentious because it surfaces the council's view before you commit to a full submission. On development that creates new floorspace, the Community Infrastructure Levy will usually also apply. None of these is the report itself, but they belong in the budget for the project as a whole.

We give a clear, fixed fee for the daylight and sunlight work once we understand the scheme and the surrounding properties, so there are no surprises. Where a quick screening at feasibility shows a full report is not needed, we will tell you and save you the cost; where it is needed, we quote it up front. Because we can produce the report alongside the design, we also avoid the coordination cost and duplication that come from bringing in a separate consultant late in the day.

The daylight and sunlight report fits into the wider Wandsworth application process, which runs from feasibility through design to submission and decision. At feasibility we survey the site and its surroundings and screen the scheme for light impact, using the rules of thumb to establish whether a full report will be needed. During design we run the BRE tests and shape the massing to keep within the guidelines, so the light case develops alongside the drawings rather than after them. When the design is fixed, we finalise the report to match the submitted scheme exactly.

The application is then submitted to Wandsworth Council for validation. The council checks that the required documents — potentially including contextualised daylight and sunlight information under its local validation checklist — are present before it registers the application; supplying a proper report up front avoids the delay of being asked for it later. Once validated, the application is publicised, neighbours are consulted, and the case officer assesses it against the Local Plan. On schemes where light is a live issue, the daylight and sunlight report and its shadow diagrams are among the documents the officer, and any objecting neighbours, will scrutinise most closely.

Wandsworth, like all authorities, works to statutory determination targets — commonly around eight weeks for a householder or minor application, longer for major schemes or where an extension of time is agreed. Where daylight or sunlight is contentious, or where a scheme goes to the planning committee, a clear and honest report is a real asset: it gives the officer the evidence to recommend approval and answers objections with numbers and diagrams rather than assertion. On genuinely marginal or sensitive sites, pre-application advice is often worthwhile, because it lets us test the council's view on the light impact before committing to a full application.

Throughout, Crown manages the process on your behalf: preparing and coordinating the report and the rest of the submission, liaising with the case officer, responding to consultation comments and, where a design change would resolve an issue, adjusting the scheme and re-running the assessment. The aim is a validated application that the officer can support and a permission granted without the avoidable delays that unquantified light concerns so often cause.

The distinctive thing about the way Crown handles daylight and sunlight is that we are the architects as well as the assessors. A standalone daylight consultant can measure your scheme and tell you whether it passes; they cannot redesign it when it does not. Because we produce the architecture and the daylight and sunlight analysis under one roof, the assessment becomes a design tool: we test early, and where a window or garden falls below the guidelines we adjust the massing and re-run the numbers, so the scheme that goes to Wandsworth is one shaped to succeed rather than one measured after the event. That feedback loop is where the real value lies.

We work to the current standard — BRE BR 209 (2022) and, for internal daylight, the BS EN 17037 metrics it now references — and we write reports for their audience: clear tables, annotated plans and shadow diagrams, with a narrative that ties every result back to Wandsworth's amenity and housing-standards policies. We are candid about the impacts a scheme has, because an honest report that makes the reasoned case for a modest, context-justified loss is far stronger in front of a case officer or committee than one that overstates compliance and is picked apart by an objector's surveyor.

We know Wandsworth. We understand the borough's tight terraced grain and small gardens, the way its 2023 Local Plan and its design and amenity policies treat light, its validation expectations, and the character constraints of its conservation areas — and we prepare daylight and sunlight reports that answer the questions this council actually asks. And because we coordinate the report with the drawings, the design and access statement and any other supporting documents, the whole application tells a single, consistent story rather than a set of contradictory ones.

Above all, we treat the report as a means to an end: your permission. Everything we do with it — assessing early, shaping the design to pass, presenting the results clearly and honestly, coordinating it with the rest of the submission, and managing the process with the council — is aimed at getting a scheme you want approved without the delay and cost that unaddressed light concerns cause. Send us the site and the scheme, and we will tell you honestly what the light position is and how best to handle it.