Curtilage: what it includes and where the line falls

Curtilage is the land that forms part and parcel with a building, and there is no statutory definition of it and no size limit. It is the concept that decides whether you can build an outbuilding under permitted development, whether a barn at the end of the garden is protected as part of a listed building, and whether a paddock counts as garden at all.

Because it is a question of fact and degree, two houses on the same street can have different curtilages, and the answer for a listed building can differ from the answer for permitted development on the same plot.

Why size does not settle it

Early cases suggested curtilage was necessarily a small area close to the house, and that idea still circulates. The courts moved on from it. The position now is that curtilage is not confined by size, and that a large area can form part of the curtilage of a large building where the facts support it. A small area can equally fall outside it.

What the courts look at is whether the land serves the building in some necessary or useful way and is part and parcel with it, judged on three factors that have been applied consistently since the early 1980s.

• The physical layout of the land and the building, including walls, hedges, gates and changes in level that mark a boundary on the ground.
• The ownership of the land, past and present, and whether the land and building have been held together.
• The use or function of the land, past and present, and whether it has been used with the building rather than separately.

None of the three is decisive on its own. A field that has always been in the same ownership as the house, but has been farmed separately and is fenced off from the garden, will usually fall outside. A walled kitchen garden reached through a gate in the garden wall, used with the house for a century, will usually fall inside.

Curtilage and permitted development limits

For householder permitted development, the outbuilding class allows buildings and enclosures required for a purpose incidental to the enjoyment of the dwellinghouse, within the curtilage of the dwellinghouse, subject to conditions on height, position and the proportion of the curtilage that can be covered.

Three practical consequences follow.

The coverage limit is calculated against the curtilage, excluding the ground area of the original dwellinghouse, so getting the curtilage wrong gets the arithmetic wrong. On a large plot where part of the land is not curtilage, the available area is smaller than the title plan suggests.

Development forward of the principal elevation is excluded, which is a separate restriction and not a curtilage question, though the two are often conflated.

And building on land that is not curtilage is not permitted development at all. A garden room in a paddock beyond the garden hedge, on land that has been grazed and fenced separately, needs planning permission however modest it is. That is a common and expensive misunderstanding.

The planning unit, the red line on your application and the curtilage are three different things that often coincide and do not have to. Draw the red line to include everything necessary to carry out the development, and do not assume the red line proves the curtilage.

Curtilage listed structures

Listing has its own rule. Under section 1(5) of the Planning (Listed Buildings and Conservation Areas) Act 1990, a structure fixed to a listed building, and a structure within its curtilage that formed part of the land with the building before 1 July 1948, are treated as part of the listed building.

The effect is substantial. A coach house, a stable block, a garden wall, gate piers, a dovecote or a former dairy can all be protected to the same degree as the house itself, with listed building consent required for works affecting their special interest, and unauthorised works being a criminal offence rather than a planning breach.

Two tests run together here: whether the structure was within the curtilage, and whether it was there before the 1948 date. Historical evidence does the work, so map regression, aerial photographs, title deeds and estate records all matter. Our note on curtilage listing and section 1(5) works through what the provision actually catches.

Note that a structure built after 1948 within the curtilage is not curtilage listed by that route, though works to it can still affect the setting or the special interest of the listed building, which is a different consideration.

Paddocks, orchards and land beyond the garden

This is where most householder disputes arise, and the pattern is recognisable.

A house is bought with an adjoining paddock. The new owner mows it, puts up a post and rail fence, and starts treating it as garden. Some years later they apply to build a garage on it, or claim it is curtilage for permitted development purposes.

The change of use of land from agricultural or paddock use to residential garden is itself development requiring planning permission. It is not achieved by intention or by mowing. Authorities do enforce on it, particularly in the Green Belt and in National Landscapes where the extension of domestic curtilage into open countryside is resisted by policy.

Where the land has been used as garden for a long period, a certificate of lawfulness can establish the position. The immunity periods changed in England, so the date the use began determines the test that applies, and the evidence needs to cover the whole period rather than the start and the end.

Residential garden land also sits outside the national definition of previously developed land, which is why building a house in a back garden is treated as greenfield development in policy terms. Our notes on building a new house in a back garden and on council garden land policies cover how authorities approach it.

Evidencing the extent

If curtilage is likely to be contested, build the evidence before the application rather than during the appeal.

Historic Ordnance Survey editions showing the layout at different dates, which is the single most useful source. Title deeds and earlier conveyances showing how the land was held. Aerial photography with the capture date recorded. Photographs of the physical boundaries as they exist, with the fence line, wall or hedge clearly shown. Statutory declarations from people with direct knowledge where the use over time is the point.

Present it as a short appendix with a plan marked up to show what you say the curtilage is and why, rather than as an assertion in the covering letter. Where the building is listed, the same evidence usually belongs in the Heritage Statement supporting the application.

Where the answer is not clear, an application for a certificate of lawfulness for a proposed use or development gives you a determination you can rely on, and it is the only formal way to confirm that works would be lawful.

This is general guidance, not legal advice. Curtilage is a question of fact and degree in every case, so 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.

Enter your postcode on PlanScope to see the listing and designation constraints picked up for your property.