Opening property extents created from OS MasterMap Topography Layer

Authoritative property extents data will be available due to new freedoms to share

As part of the Public Sector Geospatial Agreement (PSGA), OS is giving new freedoms to share data.

One of these new freedoms is that from the 1 July 2020 PSGA members will be able to publish property extents created from OS MasterMap Topography Layer under Open Government Licence (OGL) terms, e.g. HM Land Registry and Registers of Scotland’s INSPIRE polygon datasets.

This, along with the new Open Identifier policy, will result in significantly more geospatial data being fully open for businesses and developers to use, free and without restriction. We will work with all PSGA members in the coming months to support them in understanding what this new freedom means for them.

Animated GIF showing a property extent boundary example of a single, domestic property

Property extent boundary example: single, domestic property. NB, red outline only.

In this example, an area of mapping shows roads and property polygons. A pink line is added to indicate the boundary of a single property. The background map is then removed so just the pink line remains, showing the shape of the boundary. 

What are property extents?

Property extents data consist of closed polygons (red lines in the images on this page) representing real-world features such as fences and walls, or non-real-world features such as where a driveway meets a pavement.

Animated GIF showing a property extent boundary example of a University

Property extent boundary example: University. NB, red outline only.

In this example, an area of mapping shows roads and property polygons with a large area in the middle showing a much larger building groups of buildings, a university. A pink line is added to indicate the boundary of the university. The background map is then removed so just the pink line remains, showing the shape of the boundary. 

Animated GIF showing a property extent boundary example of farm dwellings

Property extent boundary: farm dwellings example. NB, red outline only.

In this example, an area of mapping shows a few buildings, surrounded by green areas indicating fields and areas containing a woodland symbol. A pink line is added to indicate the boundary of the buildings and the associated fields. The background map is then removed so just the pink line remains, showing the shape of the boundary. 

FAQs about property extents data

Read some of our most frequently asked questions about property extents data.

Can I just publish the datasets without telling OS?

If you meet our simple publishing criteria, you don’t need to ask us permission to release your dataset – just simply let us know you're about to publish.

Why isn’t OS publishing a property extents dataset under OGL terms?

OS MasterMap Topography Layer shows the physical features on the ground at the time of survey, it never shows legal property boundaries, nor does it show ownership of physical features.

The vast majority of feedback received during engagement with the geospatial industry on this element of the Open MasterMap policy, stated that OS releasing a property extent dataset under OGL terms would cause confusion and be likely to lead to misuse of the data, for example, in the high value use case of conveyancing. This was due to the likelihood that it would be seen as authoritative, but would have no basis as such. The Geospatial Commission decided that OS should not release a property extents dataset under OGL, but deliver this element of the policy by removing OS restrictions on PSGA members publishing their authoritative data under these terms.

More information about the difference between OS data and HM Land Registry property data can be found on our property boundaries page.

Can I associate TOIDs or UPRNs with my extents?

Yes, in fact we would encourage you to do so.

Can I overlay my extents on non-OS data?

Yes, in line with the OGL license, we simply ask that you acknowledge us with "Contains OS data © Crown Copyright and database right (year)"

OS OpenData support

Large sections on some of my extents happen to coincide with building outlines. Is this OK?

Yes, we accept this is the inevitable outcome of the policy. All we ask is that you focus on the whole extent and make no attempt to attribute separate portions of your extents that either identify a section as being part of a building, or create a situation where a full detailed building footprint can be back-engineered from the data you release.

Related information

  • Publishing OS derived data

    If you use OS data to create a derived dataset, there are times when you’ll want to publish this. Discover how.

  • Open ID policy

    Our Open Identifiers (ID) policy makes it easier for third parties to share information and link datasets.