Daylight & Sunlight Report for Planning: 2026 Guide
You have drawn up plans for your extension or new build. Then the council, or a neighbour, mentions “loss of light”. Suddenly you are being asked for a daylight and sunlight report — and you are not sure what it is, whether you really need one, or what happens if you skip it. This guide explains it all in plain English.
What is a daylight and sunlight report?
It is a short technical report that measures how much natural light your project would take away from the buildings around it. It looks at your neighbours’ windows and gardens, works out how much daylight and sunshine they get now, and how much they would get after your project is built. The results are compared against national guidance, so the council gets numbers instead of opinions.
That last part matters. Without a report, a “you’ll block my light” objection becomes one person’s word against another’s. With a report, there is a clear answer either way.
Who sets the rules?
In the UK, the rulebook is a guide published by the Building Research Establishment, known as BRE guidance (the current version came out in 2022). Almost every council in the country uses it. It is technically guidance rather than law, but planning officers and appeal inspectors lean on it heavily. If your scheme passes the BRE tests, a loss-of-light objection rarely succeeds.
The three simple tests
The BRE guide sounds complicated, but the main tests boil down to three ideas.
- The 45-degree rule. Draw a line at 45 degrees from your neighbour’s nearest window. If your extension pokes through that line, the council will want a closer look. Most officers use this as a quick first check.
- How much sky the window can see. This is called the Vertical Sky Component, or VSC. If a neighbour’s window can still “see” a good amount of sky after your project is built (27% is the benchmark), it will stay well lit. And here is the most useful number in the whole guide: even if a window falls below that benchmark, the loss only counts as noticeable if the window keeps less than 80% of the light it had before. Keep every affected window above 80% of its old light and you are usually in safe territory.
- Sunshine and gardens. For windows that face south (or close to it), the guide checks hours of sunshine across the year and in winter. Gardens have their own test: at least half of the garden should still get two hours of direct sun on 21 March. If your project overshadows most of a neighbour’s garden, expect that to be a problem.
When will the council ask for a report?
Not every project needs one. A small single-storey extension with generous gaps to the neighbours usually does not. But a report is commonly needed when:
- your project comes close to a shared boundary,
- you are building two storeys near a neighbour’s windows,
- you are building flats, or anything taller than the buildings next door,
- the site is in a tight urban street where homes are close together,
- a neighbour has objected about light, or
- the council’s validation list simply requires one for your type of scheme.
If you are unsure, ask the council’s planning department, or check the validation requirements on their website before you submit.
Why it helps you get approved
People think of a daylight report as a hurdle. Used properly, it is the opposite — it is evidence in your favour. Three ways it helps:
First, it deals with objections. If a neighbour claims your extension will make their kitchen dark, and your report shows their window keeps 85% of its light, the objection loses its force. Officers have to weigh evidence, and numbers beat feelings.
Second, it catches problems while they are cheap to fix. If the report shows one window failing a test, a small design change — pulling back a metre, lowering a roof slope, angling a wall — can often fix it before you apply. That is far cheaper than a refusal.
Third, it speeds up the decision. Applications with the right documents attached move through validation and assessment faster. Missing documents are one of the most common reasons applications stall.
What does it cost, and how long does it take?
Prices vary with the size of the job, but for a typical householder scheme a daylight and sunlight report is one of the cheaper documents in your application — usually a few hundred pounds, not thousands. Specialist firms work from your existing and proposed drawings, so you rarely need a site visit. Fixed-fee providers such as Fortress Associates (details at https://clockfortress.com/fortress-associates/) deliver BRE-based reports in around 4 to 5 working days from your drawings, which fits neatly into most application timetables.
One tip: have your existing and proposed drawings ready before you ask for quotes. Every assessor will need them, and sending them with your first email gets you an accurate price and timeline straight away.
A quick word about “right to light”
You may have heard the phrase “right to light”. That is a separate legal matter between property owners, decided under property law — not planning. A planning daylight report and a legal right-to-light claim are different things. Getting planning permission does not remove a neighbour’s legal rights, and vice versa. For most home projects, the planning tests are what matter; right-to-light disputes are rare and mainly affect larger city schemes.
The bottom line
If your project is close to neighbours, assume light will come up. Check the 45-degree rule yourself on your drawings. If it looks tight, get a daylight and sunlight report early — not after an objection lands. It is quick, it is one of the cheapest reports you will buy, and it turns the weakest point of your application into evidence that supports it. In planning, the applicant with the numbers usually wins.
Fortress Associates – https://clockfortress.com
