A right to light is a private property right held by your neighbour, entirely separate from planning permission. If your extension cuts the light to a window that has an established right, you could face damages or, more rarely, an injunction. Before you finalise your design, commission a desktop or specialist right-to-light risk check from a surveyor.
TL;DR:
- A statutory right depends on 20 years of continuous, open enjoyment, measured backward from a claim; register a Light Obstruction Notice before that period ends.
- Planning consent and a 45 degree council guideline do not decide private rights: a neighbour may still claim if an established window loses adequate light.
- Start with a title check and desktop assessment before fixing designs; commission a full room by room Waldram or computational report only if risk appears.
- Courts can award compensation or order work stopped or reversed; recent decisions favor negotiating damages, but injunctions remain possible in some disputes.
- Check deeds and titles early, then price redesign against settlement; arrange neighbour discussions before construction and ask your broker about project insurance.
Table of Contents
- What is a right to light and where does it come from?
- How is a right to light acquired, and how can it be stopped?
- Does planning permission remove right-to-light risk?
- How do surveyors assess right-to-light risk, and what does it cost?
- What happens if a neighbour makes a claim?
- What should you do to prevent or manage right-to-light claims?
- When do right-to-light steps fit into your project timeline and budget?
- Why we build risk control into every extension
- How we can help you plan a risk-aware extension
- FAQ
- Sources
What is a right to light and where does it come from?
A right to light is a negative easement: it stops a neighbouring owner building in a way that cuts the natural light reaching a defined opening, such as a window or rooflight. It is a property right attached to your neighbour's land, and it can be enforced in court. It has nothing to do with the public-law amenity checks a council makes.
A right can arise by grant or prescription. One common route is the Prescription Act 1832, which provides for a right after 20 years of continuous, open enjoyment of light. The Law Commission's report on rights to light explains that these rights arise by grant or prescription, and that remedies include injunctions or damages.
How is a right to light acquired, and how can it be stopped?
Under the 1832 Act, the 20 years must be the period "next before some suit or action", so the clock is tested at the moment a claim is brought. A neighbour may have an established right where a window has enjoyed light for the required period, which is why older houses can carry rights on their side and rear elevations.
Lost modern grant and common-law prescription do the same job by different legal reasoning. In practice they are used less often than the statutory route, so most disputes turn on the 20-year test.
You can interrupt the process with a Light Obstruction Notice (LON) under the Rights of Light Act 1959. HM Land Registry's practice guide 62A explains that a properly registered LON acts as a notional obstruction, but the timing rules are strict. If a right is about to mature, a notice has to be registered before the 20 years are complete, so leave margin and take legal advice before relying on one.
Does planning permission remove right-to-light risk?
No. Councils judge daylight and amenity as a matter of public law. Many use simple heuristics, such as Birmingham's 45-degree code for residential extensions, where a line drawn from the nearest habitable window shows whether an extension is likely to be acceptable. That is a planning-era rule of thumb, not a legal test for rights of light. Our guide to the 45-degree check shows how to run it on your own plans.
Local guidance also makes the point that an established right to light is not a planning consideration, though developers should address it early to avoid delay and cost.
Picture a rear extension that passes the 45-degree test and gets consent. The neighbour's kitchen window could still lose enough light to support a civil claim. RICS warns that consent gives you no protection from that claim. If your side extension sits close to a boundary, our side extension planning rules cover the planning side of the same site.
How do surveyors assess right-to-light risk, and what does it cost?
Courts ask whether a room stays "adequately lit" for ordinary use. RICS guidance describes the Waldram method as an objective proxy for that test. The method assesses the light reaching points within a room against the standard of adequate light for ordinary use. A surveyor can explain which assessment method is appropriate for the project.
Typical fee bands show why an early check is cheap insurance:
- Desktop assessment: A preliminary view of whether a window is likely to be affected.
- Full Waldram or computational report for a small scheme: Room-by-room results you can use in negotiation.
- Complex modelling: Often used for multi-window or contested sites.
A desktop check may cost less than a redesign mid-build, but ask for a project-specific quote.
What happens if a neighbour makes a claim?
Courts can choose between two remedies: an injunction, which stops or reverses the works, or damages, which compensate for the loss. Recent case law points towards money. A 2025 decision on Ludgate House illustrates that courts may award negotiating damages rather than an injunction. Injunctions remain possible, so a low chance is not a zero chance.
The outcome depends on the circumstances of the dispute. Approaching the neighbour early can help you explore a resolution.
If a risk turns up before you build, negotiating with the affected neighbour, including paying compensation, is usually the cheapest route. Litigation is slow, uncertain and typically costs more than a settlement.
What should you do to prevent or manage right-to-light claims?
RICS standards cover practitioner testing, remedies, ADR and insurance, and urge project-specific legal advice. Work through the steps in this order:
- Check your deeds and title for any registered rights or restrictions on neighbouring windows.
- Commission a desktop survey before the design is fixed.
- If risk appears, redesign with a set-back, lower eaves or a rooflight, or weigh that against the cost of a settlement.
- Open a conversation with the affected neighbour and aim for a deed of release, with compensation if needed.
- Use mediation or another form of ADR if talks stall, rather than going straight to court.
- Ask your broker about insurance cover for the scheme.
Pro Tip: Ask the surveyor to price both a redesign and a likely settlement, so you compare real figures before committing to either.
Rooflights and lanterns can help here, as this partner article on lighting a kitchen shows for your own interior.
When do right-to-light steps fit into your project timeline and budget?
Slot each check into the stage where it costs least:
- Pre-design: title check and a desktop scan, using the lower fee band above.
- Design stage: full survey only if the desktop result shows risk, so you only pay for it when needed.
- Pre-construction: neighbour negotiation, any LON strategy, and Party Wall notices, since these have their own notice periods.
- Build stage: insurance in place and a contingency held back for settlement or minor redesign.
Party Wall Act notices and permitted development timelines run alongside right-to-light action, so plan them together. For help budgeting your drawings, see our note on extension planning drawings. Our semi-detached extension ideas cover planning and party wall surprises on shared boundaries. Settlement figures vary widely, so ask your surveyor for a site-specific range rather than relying on a general figure.
Why we build risk control into every extension
Disputes can start in the first design sketch, not on site. A neighbour's window can sit close to the boundary, go unchecked, and prompt an objection once the scaffolding is up. That risk can be reduced through early checks.
We run one team across design, planning and building regulations, so potential light impacts can be considered while the drawings can still change. Clear budgets reduce late surprises. A contested claim may still need a specialist solicitor, and we will tell you when that applies.
— Raja
How we can help you plan a risk-aware extension
If you want an extension that is designed with your neighbours' windows in mind from day one, our managed service keeps the whole job under one roof. Contact us at concept or pre-planning stage, so surveys and neighbour conversations happen before drawings are fixed.
- Managed design and build, with planning and building regulations handled by us
- Realistic budgets set before any site survey
See our extension services or use our West Midlands extension cost guide to start budgeting, then ask us for a site-specific check.
FAQ
Is there a right to light law in the UK?
Yes. A right to light is a private easement, most often acquired under the Prescription Act 1832 after 20 years of uninterrupted enjoyment. It sits apart from planning law.
Can I extend 4 metres without planning permission?
Permitted development rules can allow some rear extensions without a full application, subject to conditions on your house type and location, so check your site before you rely on it. Permission under those rules does not remove a neighbour's private right to light, so the risk check still applies.
Can I extend more than 6 metres?
Larger extensions usually need more than the standard permitted development route, such as prior approval or a full application, depending on your property. Greater depth also tends to raise right-to-light risk for neighbouring windows, so a survey is sensible before you commit.
Can I refuse a neighbour access to build an extension?
Access arrangements are normally dealt with under the Party Wall Act process rather than by simple refusal, and a neighbour's refusal can complicate a project. Take advice early, as this is a legal question that depends on your boundary and the works involved.