This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol3", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
The expression "right to light," though often used, is apt to mislead by engendering false ideas concerning the true nature of the issues, when there are disputes between neighbouring proprietors about windows in houses, whether new or old, and about structures which interfere with the free access of light to those windows.
Really the question at issue when a "light" case comes to trial in a Court of Law is not whether an owner or occupier has a right to open one or more new windows or to enlarge old ones, but whether, under the circumstances of each case, the owner or occupier of the building in which the windows are, has a right to demand that the owners or occupiers of neighbouring land and buildings should not obstruct the light which would ordinarily reach the windows but for the obstruction. Every owner of land is entitled to the free use of all the light which reaches his land, whether it comes vertically or across the land of his neighbours. Also an owner is prima facie entitled (subject to any laws or authorised bye-laws or special contracts affecting his rights) to build upon his land where and when he pleases, and to erect any kind of buildings in any position and of any extent and height, and to open just as many windows as he likes, and in any positions. He is under no legal obligation to consult his neighbours when planning his own buildings, and (assuming that his property is not burdened as a servient tenement by restrictive easements in favour of neighbouring properties) his neighbours will have no right to interfere with his building operations, and he cannot be compelled to close or in any way to alter the position or size of any of his windows new or old.
The right of a man to build as and when he likes on his own land is a natural attribute of the ownership of land, and his right to take in light through any openings he may select follows from his natural right to use and enjoy all or any part of the light which reaches his land from any direction.
A neighbour can only acquire a right to object if he can show that the owner, in building, has committed some trespass or other actionable wrong. He must allege and prove either a breach of contract or a "tort" in the nature of a nuisance of which the law can take cognisance. A common ground of objection to new buildings is that they wrongfully obstruct the enjoyment of some easement appertaining to the ownership of a neighbouring tenement.
An easement is a kind of privilege appertaining to the ownership of a particular tenement, which entitles the owner or occupier for the time being, in virtue of his ownership or occupancy, to restrain the owner or occupier of a neighbouring tenement from doing anything to interfere with the enjoyment of the privilege.
An objector who sets up an easement claims to be especially privileged in so far as he sets up claims which, if established, will give him a right to restrain the free and full enjoyment of his natural rights by a neighbouring owner. For example, a neighbouring owner or occupier may say to the person building, " there have been windows in certain definite positions on my property to which light has passed uninterruptedly across your land for more than twenty years, and I have a prescriptive right to restrain you from interfering with the light which would reach my windows but for your action in building so as to interrupt the free flow of light to these windows." He thus claims dominant rights for his tenement over the neighbouring tenement.
Most disputes about "light" between owners of neighbouring properties take the form of disputes about an alleged right to have free access of light to particular window spaces from across a neighbour's land.
In the absence of specific contracts restricting the natural rights there can be no dispute about the right of an owner to open windows in his own tenements, but only about a right to stop light en route to particular places.
An easement to uninterrupted light can only be claimed with reference to windows in buildings. There can be no light easement for a piece of open ground which has never been built upon, so that although, as before stated, the owner of the open land can freely use and enjoy all the light which reaches it at any time, he cannot restrain his neighbours from erecting buildings all round which may have the effect of diminishing to any extent the total light which can reach his open space. It has been held that an easement of light cannot be acquired by prescription for an open saw pit. It has also been held that a built-up open structure of scaffolding, or open floors, or stages supported on piles, was not such a building as to support a claim for easement of light. Usually a definite covered building with definite openings or windows to admit light are necessary before any claim for ancient lights can be established, although the right may be preserved even after the demolition of the original buildings for the benefit of other buildings to be erected on the same site.
Until some definite easement rights have been acquired, all neighbours are on an equal footing as regards their rights to build ; and while they may all open any windows they please, as before stated, they may also all build as they like and block each other's lights to any extent, provided, of course, that they do not so build as to trespass on their neighbour's land by overlapping or by any other means.
If next-door neighbours build in opposition to each other, he who builds the highest is able to obtain the greatest quantity of light, and ultimately to obtain an easement of light over neighbouring properties, unless the neighbours are able in time to run up walls or screens so as to block the higher windows which face over their land.
With reference to what has been said about the right of every owner to open windows anywhere he likes on his own property, it is important to know that the neighbours cannot acquire any legal right to restrain the opening of any window on the ground that privacy will be invaded by people looking through the window into their gardens or other places within their tenements which they would like to keep private.