Glossary and Jargon Buster

A–Z Rights of Light Glossary

A — Actionable Interference

A substantial interference with an established right to light that is serious enough to give the affected owner a potential legal remedy.

 

A — Aperture

A defined opening, normally a window, through which natural light enters a building and to which a right to light may attach.

 

B — Beneficial Use

The ordinary use of a room for which sufficient natural light is required; the legal assessment is concerned with adequate light for ordinary purposes rather than maximum possible light.

 

C — Compensation

Money awarded or negotiated to compensate a property owner for an actionable loss of their right to light, instead of—or in some circumstances alongside—other remedies.

 

C — Cooper & Ors v Ludgate House Ltd

A leading 2025 High Court rights-of-light case confirming that an actionable infringement can result in substantial negotiating damages even where the court exercises its discretion not to grant an injunction. Read about Cooper & Ors vs Ludgate House Ltd here.

 

D — Damages

Financial compensation awarded by a court following an infringement of a right to light, where damages are considered an appropriate remedy.

 

D — Daylight

Natural light entering a building from the sky; in a rights-of-light context, the relevant question is whether sufficient daylight remains for the ordinary use of the affected room.

 

D — Deed of Release

A legal document by which a property owner releases or gives up a right to light, usually in return for an agreed payment from a developer.

 

D — Dominant Tenement

The land or property that benefits from an easement, such as a right to light.

 

E — Easement

A legal right enjoyed by one piece of land over another; a right to light is a type of private property easement.

 

F — Fifty–Fifty Rule (50:50 Rule)

A commonly used rights-of-light measurement under which a room is generally considered adequately lit where at least 50% of its working area receives at least 0.2% of the sky’s light under the Waldram method; it is a technical convention, not a statutory rule.

 

I — Injunction

A court order that can prevent, restrict or require the alteration of building works that infringe a right to light; the availability and appropriateness of an injunction depends on the circumstances of the case.

 

I — Infringement

An actionable interference with an established right to light, typically caused when a development substantially reduces the protected light reaching a building.

 

L — Light Obstruction Notice (LON)

A statutory notice that can be used to interrupt the acquisition of rights to light by prescription by registering a notional obstruction; it is particularly important because statutory time limits can apply after service. Learn more about Light Obstruction Notices.

 

L — Loss of Light

A reduction in the amount of natural light reaching a property, usually assessed to determine whether an established right to light has been infringed.

 

L — Loss of Daylight

A general description of reduced natural illumination. It is important to distinguish this from a legal right of light, which is a private property right and is assessed differently from planning-based daylight assessments.

 

N — Natural Light

Daylight entering a building from the sky rather than artificial illumination; sufficient natural light is the subject matter protected by a right to light.

 

O — Obstruction

A building, extension or other structure that blocks or reduces the amount of natural light reaching a window or other protected aperture.

 

P — Prescription Act 1832

The legislation under which many rights of light are acquired through long, uninterrupted use; section 3 provides the statutory basis for acquiring a right after 20 years' enjoyment in the circumstances prescribed by the Act. Read the Prescription Act 1832.

 

P — Private Legal Easement

A private property right benefiting one property and burdening another; a right of light is a form of private easement rather than a planning permission or public right.

 

R — Right of Light

A legal easement giving a property the right to receive sufficient natural light through defined apertures, such as windows, for the ordinary use of the building.

 

R — Right of Light Assessment

A technical and legal assessment examining whether a development is likely to infringe an existing right of light, commonly involving a Waldram analysis together with examination of title and other legal documents.

 

R — Right of Light Claim

A legal claim brought where an established right to light is alleged to have been infringed by a neighbouring development or other obstruction. Learn more about right of light claims.

 

R — Right of Light Injunction

An application for a court order seeking to prevent or restrict development, or require offending works to be altered, because of an alleged infringement of a right to light. Learn more about right of light injunctions.

 

R — Right of Light Surveyor

A specialist surveyor who assesses the technical impact of development on rights of light, commonly using the Waldram method and related analysis.

 

S — Servient Tenement

The land or property over which an easement exists and which is subject to the rights benefiting another property.

 

S — Settlement

An agreement between the affected property owner and developer resolving a rights-of-light dispute, commonly involving payment of compensation and/or other agreed terms.

 

S — Sky Factor

The proportion of light from the sky reaching a reference point compared with the light that would reach the same point under an unobstructed sky; the 0.2% benchmark is traditionally associated with the Waldram approach.

 

S — Sufficiency of Light

The legal concept that a property is entitled to sufficient light for the ordinary use of the room, rather than an absolute right to preserve every existing ray of daylight.

 

T — Title Deeds

Documents relating to ownership and property rights which can help establish whether a right of light exists and whether it has been granted, reserved, released or otherwise affected.

 

W — Waldram Method

This is the traditional technical method used to assess rights of light by determining how much of a room receives at least the accepted minimum level of sky illumination. It originated from the work of Percy Waldram and is still widely used in rights-of-light surveying.

 

W — Working Plane

Used when assessing the distribution of daylight, it is a horizontal reference plane within a room, traditionally representing the level at which normal activities such as reading or working take place.

 

20-Year Rule

The commonly encountered rule that a right to light may be acquired through 20 years of uninterrupted enjoyment under the Prescription Act 1832, subject to the precise legal requirements and circumstances.