Light Obstruction Notices

It’s time to optimise and protect the value of your investment. A Light Obstruction Notice (LON) prevents the acquisition of Rights to Light where no rights currently exist. GIA is experienced in leading this process and serving Light Obstruction Notices on behalf of clients.

We also advise owners of properties where notices have been served. GIA’s LONs service is managed by our In-House Lawyer. To find out more, email and a member of our dedicated team will get in contact. Alternatively download our LONs procedure or request a CPD.



Windows (or apertures) will acquire a legal right to light if they have had access to such light for 20 years.  In order to prevent this acquisition of a right to light, the light must be interrupted for a period of 12 months, or one year.  After this period of interruption, the building’s apertures will not acquire rights to light for a further 20 years.

The most obvious way of interrupting an aperture’s light is by constructing a building opposite. However, there is an alternative legal mechanism for interruption: a legal notice can be registered on the opposite building which ‘notionally obstructs’ the light. This is called a Light Obstruction Notice (LON). 

A LON is a charge that is entered on the Land Register on the title of a piece of land. According to Section 2 of the Rights of Light Act 1959, a developer is permitted to serve a LON on a nearby building to create a notional obstruction across the totality of the site boundary, as an alternative to a physical obstruction. From the point a LON is registered, the requisite one-year period of interruption begins. This prevents the acquisition of prescriptive rights of light.

If the LON is registered before a building has reached 19 years and 1 day old, and is successfully unchallenged, then the prescriptive clock will be reset to zero. The affected building owners will therefore be unable to exercise a prescriptive right to light over the development site for another 20 years.

The potential for the development of a site can be prevented, or at least hampered, if neighbouring properties have rights to light and any proposed construction would impact their legal rights.  It might be possible for such a neighbour to obtain an injunction to prevent (or at least reduce) the development. Alternatively, a developer could be ordered to pay the owner(s) of any impacted property a sizeable amount in compensation to enable any new construction to be built.

Lawyers have historically questioned whether LONs should be registered prior to a building (or it’s apertures) reaching 18 years and 1 day old. In GIA’s experience, LONs can still be successfully registered up to 19 years and 1 day. However, GIA suggests, as a matter of good practice, to register prior to the 18 year and 1 day mark.

For the proper registration of a LON, the law requires all relevant interests in the affected building to be notified (i.e. freeholders, leaseholders, tenants, mortgagees etc). Ensuring these notifications are properly notified is included as part of GIA’s offering.

From start to finish, applying, registering and serving notification of a LON takes around 3 months.

There are two different procedures to choose from when registering a LON:

  1. The Standard Procedure
  2. The Expedited Procedure – this route is recommended when there is a high likelihood that the apertures of the relevant properties are nearing 19 years and 1 day old. This procedure registers a LON more quickly (subject to an additional cost) to mitigate the risk of running out of time to prevent the neighbouring property from acquiring rights.

Using the expedited procedure ensures that the LON is registered prior to serving notice to the interest holders. Should this procedure be preferred, GIA can ensure that the LON is registered within 2-3 weeks. In contrast, if the normal procedure is elected the LON will be registered within 8-12 weeks.

Download our LONs procedure here.

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Deia Russell-Smith