Checking site constraints on the national planning data service

The national planning data service will tell you in about four minutes whether a plot sits in a conservation area, inside the Green Belt, within a National Landscape or under an Article 4 direction. It will not tell you that a plot is clear. That distinction is the whole skill of using it, because the platform is assembled from data published by individual planning authorities and national bodies, and publication is uneven. A blank map means nobody has published a dataset covering that square, not that nothing is designated there.

Used properly, the service is the fastest first pass available for a site check, and it is free.

What the platform holds

The service brings together national designations and locally published ones in a single map and a set of dataset pages. National layers include Green Belt, National Parks, National Landscapes, sites of special scientific interest, ancient woodland and heritage designations drawn from the statutory lists. Locally published layers include conservation areas, Article 4 directions, tree preservation order zones, local plan boundaries, brownfield land registers and site allocations.

Each record on the map is an entity with its own page. That page gives a reference, a name, a geometry, the organisation that published it, a start date and, where the designation has been revoked or superseded, an end date. The end date is the field most people miss.

Some things are deliberately absent. Flood zones live on the Environment Agency flood map for planning, and protected species records, nutrient neutrality catchments and other natural environment layers live on Defra's mapping service. Neither is duplicated here.

Checking by address and by boundary

Start with the postcode search to get to the right place, then switch to working with the boundary rather than the point. A point check answers whether the centre of a plot is in a designation. It does not answer whether the designation clips the corner where you intend to build, and on a long garden plot that difference decides the application.

Zoom in until individual buildings are distinguishable and turn layers on one at a time. Turning everything on at once produces a wash of overlapping colour that hides thin linear designations such as a conservation area boundary running along a rear garden line.

Check the surroundings as well as the site. A listed building 40 metres away puts your proposal in its setting, which engages the statutory duty under the Planning (Listed Buildings and Conservation Areas) Act 1990 whether or not your own plot carries any designation at all. Ancient woodland within 50 metres brings a buffer expectation. A protected tree in a neighbouring garden can still dictate your foundation design and will need a tree survey to BS 5837:2012 before layout is fixed.

Reading an entity record properly

Open the record rather than trusting the colour on the map. Three fields decide how much weight it carries.

The organisation field tells you who published it, which tells you whether it is the statutory body or a local authority transcription. The start date tells you when the designation took effect, which matters for Article 4 directions because permitted development removed by a direction is removed only from the date the direction comes into force. The end date, where present, tells you the designation has gone.

Geometry accuracy varies. Conservation area boundaries digitised from a paper appraisal map can be out by several metres, which is the difference between inside and outside for a plot on the edge. Where the boundary runs close, the designation document held by the council is the authority, not the digitised line.

Where coverage is thin

Article 4 directions are the clearest example. Many authorities have published them, some have not, and a direction that removes householder permitted development across a whole suburb may simply not appear. The same applies to tree preservation orders, where some authorities publish full order polygons, some publish indicative points and some publish nothing.

Local plan allocations and policies map layers are patchier still. Neighbourhood plan areas, local green space, employment allocations and settlement boundaries are all locally published and frequently absent.

Treat the platform as complete for national designations and indicative for local ones. That single rule prevents most of the mistakes people make with it.

What the check does not reach

Several constraints that will stop a scheme never appear on any planning map. Coal mining legacy is one: a shaft or shallow workings under a plot is recorded by the mining records authority rather than the planning system, and mine entries and coalfield conditions routinely appear as conditions on permissions in referral areas.

Others include restrictive covenants on the title, rights of way not yet recorded on the definitive map, private drainage easements, utility apparatus, ransom strips and any pending designation that has been consulted on but not made. Land in a National Landscape carries a statutory duty on the decision maker, and how that duty is applied is a policy question the map cannot answer.

Flood risk deserves its own step. Check the Environment Agency flood map for planning for zones 2 and 3, and check surface water risk separately, because a site in Flood Zone 1 can still need a Flood Risk Assessment where it exceeds one hectare or where surface water risk is recorded.

Cross-checking against the council's own map

The adopted local plan policies map is the authoritative local document, and it is published by the authority rather than by the platform. Open it alongside the national service and reconcile the two. Where they disagree, the policies map wins for plan-level designations and the statutory register wins for statutory ones.

Four registers are worth going to directly:

1. The National Heritage List for England, for listed buildings, scheduled monuments and registered parks, including the list entry text that describes what is protected.
2. Defra's magic mapping service, for sites of special scientific interest, special areas of conservation, special protection areas, priority habitat and ancient woodland.
3. The Environment Agency flood map for planning, for flood zones and the associated data the authority will expect you to cite.
4. The council's own conservation area, Article 4 and tree preservation order registers, which are usually held as documents rather than as map layers.

A sequence worth repeating

Run the same steps in the same order on every site and record the output, because a constraints check has a shelf life and you will be asked when it was done.

1. Draw or upload the red line boundary, not a point.
2. Run the national platform layer by layer and screenshot each hit with the entity reference visible.
3. Run the heritage list, the Defra map and the flood map for planning.
4. Open the adopted policies map and compare.
5. Check the council's Article 4 and tree preservation order registers directly.
6. Write down the date of each check and the source, in a single table at the front of the file.

That table is what goes into the planning statement and what an officer will read first. It also tells you, before you spend anything on drawings, which specialist reports the site is going to need.

Browse all 66 PlanScope report types and start a draft once you know what the constraints check has turned up.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.