How New Buildings Affect Your Existing Right of Light

By RightsOfLight.org.uk · 19 September 2026

When a new building goes up near your property, the impact on your daylight can be dramatic. But at what point does a new development actually cross the line from being an annoyance into a legal infringement of your right of light? This is one of the most common questions property owners ask, and the answer depends on several factors that courts have developed over more than a century of case law.

A right of light is a legal entitlement to receive daylight through defined openings in your building. If you want to understand what a right of light is and how it comes into existence, the starting point is the Prescription Act 1832. Once a window or other aperture has received daylight without interruption for 20 years, the owner of that building acquires a legal right to continue receiving that light. The right attaches to the building, not the person. So even if the property changes hands, the right remains.

Infringement happens when a new building or extension reduces the daylight reaching your rooms below a level the law considers adequate. Courts do not require that all light be blocked. The test is whether the remaining light is sufficient for the ordinary use of the room. For a dwelling, that typically means enough natural light to read or work by in the daytime. For commercial premises, the standard is broadly similar, though context matters.

Surveyors assess this using a method known as the Waldram diagram, which maps exactly how much sky is visible from different points across a room. The standard benchmark is the 50/50 rule. If more than half the room measured at table height (roughly 850mm above floor level) falls below 0.2% of the sky factor, the room is considered inadequately lit. When a proposed or completed building pushes a room past this threshold, an actionable infringement exists. The technical side can seem daunting, but a specialist surveyor will handle the modelling and explain the results in plain terms.

What many property owners do not realise is that planning permission does not protect a developer from a rights of light claim. Local authorities grant planning consent based on public planning policy. Your right of light is a private legal right, and it operates entirely separately. A developer can have full planning approval and still face an injunction or a damages claim if their building interferes with your light. This distinction catches many people off guard, but it is well established in English law.

The type of building causing the interference matters less than the effect it has on your light. A tall office block, a new block of flats, or even a two storey residential extension can all infringe a right of light if they reduce your daylight below the adequate threshold. Location plays a big part too. In dense urban areas, even modest increases in building height can tip rooms that are already borderline into insufficiency.

If you believe a new building has reduced or will reduce the daylight in your home or business premises, the first step is to find out whether you can make a claim. Acting early gives you more options. Before construction starts, courts are far more willing to grant an injunction preventing the building from being completed in its current form. After the building is finished, the courts lean more towards awarding financial compensation instead, though injunctions including demolition orders remain possible in exceptional cases. The Supreme Court confirmed in Coventry v Lawrence (2014) that the court retains discretion to grant an injunction even where damages might seem more convenient.

Compensation in rights of light cases is typically calculated by reference to a share of the developer's profit from the part of the building that causes the infringement. You can read about how compensation is calculated in more detail, but the general idea is that the court looks at what a willing buyer and willing seller would have agreed to release the right. This often results in a meaningful sum, particularly where the development is large or the infringement is significant.

If you have noticed changes to the daylight in your property because of nearby construction, do not assume you have no options. Many property owners simply accept the change without investigating their legal position. Getting a professional assessment early on can make a real difference. You can request a free assessment to understand where you stand and what your next steps might be.

Reference: Prescription Act 1832; Colls v Home and Colonial Stores Ltd [1904] AC 179; Coventry v Lawrence [2014] UKSC 13