Ordnance Survey MasterMap for Planning Applications

What the Topography Layer provides

The data represents mapped physical features such as buildings, roads, paths, land and structures in a detailed, structured form. A plan supplier or design team can use an extract as the base for a location plan, block plan or CAD drawing.

The date of the extract matters, but no mapping product should be assumed to show a site change immediately. Compare the map with the current site and flag material differences to the designer or planning authority.

Topography is not legal title

A wall, fence, hedge or other line on OS mapping records a physical feature within the product specification; it is not proof of who owns it or exactly where the legal boundary lies. HM Land Registry title plans usually show general boundaries and serve a different registration purpose.

• Define the red planning application site deliberately
• Use title documents to investigate ownership, not as a substitute planning map
• Obtain legal or surveying advice where an exact disputed boundary matters
• Do not infer private rights of access from the map alone

Licensing, output and UK coverage

Use an extract and output licensed for the intended planning or design use, and keep the required acknowledgement and licence details on the issued sheet. PDF, CAD and GIS outputs can all derive from the same source data; file format does not increase the surveyed accuracy of that data.

OS MasterMap covers Great Britain. Northern Ireland has separate OSNI products, including the official address-centred ACEmap service described by nidirect.

Check currency against the site

Use the most recent suitable extract available, then compare important features with the site as it exists. Recent construction, demolition, access changes, fences, paths or planting may not yet appear in the data, and a planning drawing should not present a known historic layout as current.

• Record the extract or issue date
• Inspect current aerial or site evidence only as a check, not as an unlicensed substitute map
• Add verified existing features from appropriate survey information
• Explain a material discrepancy where it affects how the proposal is understood

Know when a measured survey is needed

MasterMap is often an effective base for locating and contextualising a proposal, but it is not designed to supply every project measurement. Obtain measured building, topographical, tree or utility survey information where the design depends on accurate levels, eaves and ridge heights, boundary clearances, drainage, retaining walls or construction setting-out.

Keep the source of each layer clear. Combining OS context and survey data in CAD does not make them the same type or accuracy of information.