Green Belt and grey belt: can it be built on?

Green Belt keeps land permanently open to prevent urban sprawl ¹. It serves five purposes ¹:

• checking the unrestricted sprawl of large built-up areas;
• preventing neighbouring towns merging into one another;
• safeguarding the countryside from encroachment;
• preserving the setting and special character of historic towns;
• assisting urban regeneration, by encouraging the recycling of derelict and other urban land.

It is about openness, not beauty. A Green Belt field need not be attractive countryside, and much attractive countryside is not Green Belt. Landscapes protected for their beauty are National Parks and National Landscapes (the former Areas of Outstanding Natural Beauty), where major development should be refused other than in exceptional circumstances ⁴.

At 31 March 2026, Green Belt covered about 1,632,730 hectares, around 12.5% of England's land, and 177 of England's 296 local authorities had some ³.

Development that is not on national policy's list of acceptable kinds is inappropriate: harmful by definition, and to be refused unless very special circumstances clearly outweigh the harm, with substantial weight given to the harm to the Green Belt ¹. The acceptable kinds include ¹:

• buildings for agriculture and forestry;
• limited infilling in villages, and limited affordable housing for local needs;
• redevelopment of previously developed land that doesn't cause substantial harm to openness;
• development on grey belt, under the conditions below;
• homes or mixed-use schemes within reasonable walking distance of a well-connected station ^1,2.

Boundaries can also be changed through the Local Plan, where exceptional circumstances are fully evidenced: for example, where the council can't meet its need for homes after using brownfield land, building at higher densities and looking outside the Green Belt ¹. When land is released, previously developed land comes first, then grey belt, then other Green Belt ¹.

Grey belt is Green Belt land that is previously developed, or that does not strongly contribute to three of the five purposes: checking the sprawl of large built-up areas, stopping towns merging, and preserving historic towns ². National policy sets out how councils assess this, and says villages don't count as large built-up areas or towns for the purpose ⁵.

So grey belt is not the same as brownfield. A greenfield site can be grey belt if it does little to stop sprawl or merging, for example a field enclosed by existing development.

Building on grey belt is not inappropriate when all four of these apply ¹:

• it doesn't fundamentally undermine the purposes of the remaining Green Belt across the plan area;
• there is an evidenced unmet need for that kind of development: for housing, the council can't show a five-year supply of housing land or scored below 75% in the Housing Delivery Test ^1,6;
• the site is in a sustainable location;
• major housing schemes meet the golden rules.

See our guide to five-year housing land supply for how councils fall short.

Major housing schemes (10 homes or more, or a site of half a hectare or more) on land released from the Green Belt, or on Green Belt sites, must meet three golden rules ^1,2:

Green Belt still makes a field much less likely to be built on, but less so than before grey belt was introduced, especially at the edge of a town or village and where the council is short of housing land. Check That Field scores Green Belt at a town or village edge as a possible grey belt site, a smaller penalty than Green Belt elsewhere: see how the score works.