Building on the Green Belt.

Its boundary is drawn in the local plan, and the Framework names openness and permanence as its essential features. Policy GB2(1) of the Framework published on 17 August 2026 gives it five purposes: checking the sprawl of large built-up areas, preventing neighbouring towns from merging, safeguarding the countryside from encroachment, preserving the setting and special character of historic towns, and helping urban regeneration by recycling derelict and other urban land. Scotland, Wales and Northern Ireland set their own Green Belt policy. Section 01 shows how to check whether a site is inside the line.

The three that count are checking the sprawl of large built-up areas, preventing neighbouring towns from merging and preserving the setting and special character of historic towns. Safeguarding the countryside from encroachment is deliberately left out of the test, which is why ordinary open fields inside the Green Belt can still qualify as grey belt. Previously developed land in the Green Belt counts as grey belt as well. Land drops out again where some other designation, a heritage asset or a flood risk for instance, would itself be a strong reason to refuse.

Until local plan policies are updated, the affordable housing contribution is set at fifteen percentage points above the highest affordable requirement that would otherwise apply to the site, capped at fifty per cent. Where no requirement applied before, it is fifty per cent by default. Since August 2026 the Framework gives substantial weight to the importance of complying with the rules, which is a different and narrower steer than the old wording in favour of permission. The rules apply to major housing development, so a single house on a grey belt plot is not caught by them.

The original building means the house as it stood on 1 July 1948, or as first built if it went up after that, not the house as it is today. Since August 2026 the house itself has to be lawful and of permanent and substantial construction. Every extension since counts against the allowance, so a property that has been added to two or three times may have little headroom left. Most authorities publish a percentage they treat as proportionate. Permitted development rights are worth checking first in any case, because where they are available they sidestep the argument entirely.

Size and siting decide most of these. Something tucked against the house and subordinate to it reads differently from a separate structure standing in an open paddock, because openness is what the policy protects. Permitted development rights cover much of what people want from an outbuilding and they are the first thing to check. An annexe meant to be lived in independently is a different question again, because that is a new dwelling rather than an outbuilding.

What does switch it off is a conservation area, a National Park, a National Landscape, the Broads or a World Heritage Site, along with listing and a handful of other designations. Green Belt is not on that list. Where the right is not available, the redevelopment of previously developed land is the route worth looking at instead, since a working farm building is land that has been built on. An Article 4 direction or a condition on an earlier permission can remove the right, so both belong in the first afternoon of checking.

The test is that harm to the Green Belt from inappropriateness, plus any other harm, must be clearly outweighed by other considerations. Substantial weight is given to the Green Belt harm before the balance starts, so the case has to be strong from the outset. Unmet housing need on its own is rarely enough. What tends to carry weight is a benefit only this site can deliver. It is the hardest route on this page and the least predictable. In our experience it is where the most money gets spent for the least certainty.

Authorities are expected to review Green Belt boundaries where they cannot otherwise meet their housing need and to give priority to previously developed land and grey belt when they do. Getting a site considered means promoting it through the plan process, with evidence, over a period measured in years rather than months. It runs on an entirely different timetable from a planning application and the two are often pursued side by side rather than one after the other.