Can a dormer window cause a Legal Right to Light problem for my neighbour?

Absolutely, in certain situations, most commonly when neighbours have windows over 20 years of age.

When we consider small dormer windows that penetrate from the front or rear roof slope of a main house roof, the windows in the main vertical house wall of houses either side will not be able to see the dormer (as it will be out of site), and thus will not be affected at all.

In the case of terraced or some semi-detached houses, where rear offshoots are present built off the rear of the main house wall, again, the windows in the offshoot (commonly ground floor kitchen windows and first floor bathroom, landing or bedroom windows) will face at right angles to the main house, and will rarely be affected by a dormer window in the neighbouring main house roof slope.

So, where do problems arise?

Typically, problems can arise when people erect large dormer windows to the rear offshoot of a terraced or semi-detached house.

In such situations, neighbouring houses with rear offshoots, will look directly towards the subject house that is to have the dormer added to. 

When assessing legal right to light claims, the assessment point is a working plane at the height of 850mm above internal floor level.  This lower perspective means that often, the working plane within a room, can look out and up over a neighbour’s sloping roof covering, enabling some sky view from this lower-level perspective.



After a dormer extension to a rear offshoot, the view of the sky from the neighbour’s rear offshoot window, usually at ground floor level, can be blocked by the new mass of the dormer; the view over the sloping roof coverings is replaced by the vertical face of the dormer window, thus, sky view is reduced or eliminated.




This is where legal right to light injuries can be caused.

If light at the working plane is reduced to a certain level in the neighbouring room or rooms (that is, such that less than between 50% and 55% of the neighbour’s room(s) can see 0.2% of the sky dome), then a legal injury will occur.   Remedies available for an affected neighbour can be such that they may be able to pursue and injunction, or, compensation.

So, if you are thinking of a rear dormer window, do consider the potential impact on neighbouring windows, particular if they are over 20 years of age, where legal rights may have been established.

If you have any queries, please do contact us at [email protected], we would be pleased to answer any queries that you may have.

We have more information available on right to light assessments and issues for homeowners planning an extension or a new build. Alternatively, you can contact our team and speak with our experts. 


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