Rights of Light – A Dark Art

Guest article from Dr Peter Defoe - Partner and Business Systems Manager at Calfordseaden LLP  

A small group of Surveyors and others practice in the field of rights of light.  Few people outside this group understand what they do and why



Source: Google Images

Rights of Light, as an easement, have existed for nearly a thousand years with the first notion of time immemorial being 1189 and any building with windows constructed prior to this date being assumed to automatically have a right to light through those windows. Fast-forward to 1832 and the Prescription Act formalised the principle that any window that had existed for twenty years or more would have a right to light and this continues to be the case unless there is any legal agreement to the contrary.

In 1904 the law was clarified (Coll v Home and Colonial Stores 1904) to state that the right was only to sufficient light for ordinary purposes. Simply, this means that a property does not necessarily have a right to the same amount of light but that it can lose the benefit of light down to what is considered to be an acceptable minimum.

The main role of a rights to light surveyor is to be aware of the relevant law, to assess the likelihood of an actionable level of loss and to advise the client accordingly. From this they may then be instructed to advise on the possible alternatives, including reducing the scale of proposed development; calculate actual predicted losses; negotiation of settlements or appear in Court as expert witness.

First Contact

Most commonly the first approach, be it from the developer or the affected party, arrives in the form of a question asking if the development is causing or is likely to cause a rights of light issue.

What does the Surveyor do First?

The surveyor needs information and the first action is to accumulate as much as is available.

The quality of any advice is solely dependent on the information obtained so the surveyor is looking for existing and proposed drawings, surveys, and legal documents such as deeds for all properties, photographs and anything else that may be relevant.

From this the surveyor can form an initial view on the following:



·         Is the affected property older than 20 years or might the windows be in the same location as the previous property on the site, which existed for more than 20 years.

·         Is the proposed development close enough and large enough that the daylight to the subject room(s) will be affected?

·         Is there any known reason the window may or may not have acquired a right to light through prescription?

·         Does the room benefit from light through other windows that are unaffected?

 

The Surveyor should then visit the site. All too often the information that has been provided is found to be incomplete and it is only through actually visiting the site that this can become apparent.



One of the most significant factors in assessing loss will be the internal arrangement of the rooms that may be affected. For example, a window in the main part of a typical terraced house next to the rear extension will be in one corner of the room meaning that a large proportion of the room already has limited sky visibility. Very often, when acting for the developer, access is not available and the surveyor has to use local knowledge, possibly sales particulars to ascertain likely layout.

If the surveyor forms the view that there will possibly be actionable loss then the client will have to make a decision as to whether they want to instruct the surveyor to prepare actual calculations of loss. This can be an expensive process and the surveyor will make sure that his client is aware of this before proceeding.

What happens next?



The surveyor will calculate the estimated loss of daylight. The accuracy of this estimate will depend upon the accuracy of information provided. At the low end he counts bricks for window sizes. At the high end he has a cloud survey which, if he is lucky, also gives room sizes. Usually it is a combination of the various methods.

What is being measured is a representation of sky visibility at each point in the room with the threshold value being 0.2% of the total modified sky dome. The sky dome is modified because the value of the light from the sky on the working plane varies with the height above the horizon from which the light comes. Light coming from 45 degrees above the working working plane has a higher value than that coming from near the horizon or above 45 degrees. To account for this in our calculations we treat this as a modified sky dome which, when plotted on a piece of paper produces what is known as a Waldram Diagram (see below).

 

Dr P S Defoe PrD(BE) DipArb FRICS FCIArb MCQI CQP

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