Curtilage and why it limits outbuilding rights

Curtilage is the land that goes with your house, and it is not the same thing as the land you own. Part 1 of Schedule 2 to the General Permitted Development Order 2015 allows outbuildings incidental to the enjoyment of the dwellinghouse within its curtilage, and it caps the total ground covered by buildings, enclosures and containers at 50 per cent of the curtilage excluding the original house. So the curtilage permitted development meaning decides two separate things: where you may build at all, and how much of that land you may cover.

What curtilage means in planning terms

The Order does not define it. Curtilage comes from case law, and the test the courts have used looks at the physical layout of the land, the ownership past and present, and the use or function of the land in relation to the building.

For a house, the working test is the land used for the comfortable enjoyment of the dwelling. The garden, the yard, the drive, the path round the side. The land that serves the house in a domestic way.

That is narrower than a title boundary in most cases and occasionally wider. A terraced house with a long strip of land running to a back lane may have curtilage covering only the garden proper, with the far strip being something else. A farmhouse may have curtilage covering a yard the deeds treat as agricultural.

The question is one of fact, and it is answered by looking at how the land is laid out and used, not by reading the deeds.

Why it is not the same as the title boundary

Three situations show the divergence clearly.

A paddock behind the garden, fenced separately and grazed, is in the same ownership and is not curtilage. Putting a stable or a garden room on it relies on Part 1 rights that do not extend there.

A field bought from a neighbouring farm and absorbed into the lawn ten years ago may now be curtilage in fact, and the change of use from agriculture to residential garden was itself development requiring permission. If that permission was never obtained and the change is not immune from enforcement, the land is not lawfully residential and relying on Part 1 there is risky.

And a shared access or a flying freehold arrangement can put land inside your title that serves a purpose other than your domestic curtilage.

The practical consequence is that the 50 per cent calculation depends on getting the denominator right. Measure the curtilage, not the title, and if the two differ be able to explain why.

The coverage limit on buildings and enclosures

The limit in Class E is specific about what counts. The total area of ground covered by buildings, enclosures and containers within the curtilage, other than the original dwellinghouse, must not exceed 50 per cent of the total area of the curtilage excluding the ground area of the original dwellinghouse.

Three features of that wording catch people out.

The original dwellinghouse point is the one that bites on a house already extended twice. A 1960s semi with a 1985 rear extension and a 2004 side extension has already used up part of its allowance before the new outbuilding is drawn, because those extensions are not part of the original dwellinghouse.

Enclosures are the quiet one. A walled bin store, a brick-sided raised planter and a hard-sided log store can each count, and on a small urban garden a handful of them will move the percentage noticeably.

Remember too that Class E has its own dimensional limits running alongside the coverage cap, including the 2.5 metre height limit within two metres of a boundary, and height is measured in a particular way, as measuring height under Part 1 from adjacent ground explains.

Land added to a garden later

This is where householders most often go wrong, and the sequence matters.

Changing the use of land from agriculture, paddock or amenity land to residential garden is a material change of use and needs planning permission unless it is immune from enforcement. Councils in rural areas and on the edge of settlements take this seriously, because garden extension into open countryside is a recognised policy issue.

Until that change of use is lawful, the land is not part of the planning unit's curtilage, so Part 1 rights do not run on it and nothing you build there is permitted development.

There is a further consequence for the coverage sum. If the land is lawfully curtilage, it enlarges the denominator and gives you more allowance. If it is not, including it in the calculation produces a figure that is wrong in your favour, which is exactly the error an enforcement officer looks for.

Paddocks, orchards and the agricultural edge

On a rural property the boundary between domestic and agricultural land is often invisible on the ground and very visible in the planning history.

Signals that land is not curtilage include a separate access, separate fencing, grazing, a crop, an agricultural rating assessment, and a use that serves something other than the house. Signals that it is curtilage include mown lawn, ornamental planting, domestic storage, children's play equipment and a continuous open relationship with the garden.

Mixed signals are common. An orchard that was commercial in 1950 and has been mown as part of the garden since 1990 is probably curtilage now, and establishing that may need evidence rather than assertion.

Where the land is agricultural, different rights may apply instead. Part 6 permits certain agricultural buildings on holdings above a size threshold, with its own conditions and a prior notification procedure, and it is a different regime from Part 1 rather than an extension of it.

Evidence of the curtilage as it existed

Where the position is contested, assemble the evidence before the argument starts.

Historic Ordnance Survey mapping shows boundaries, enclosures and the extent of garden at successive dates. Aerial photography shows ground cover and mowing patterns. The registered title and its plan show ownership and any changes. Council tax and rating records sometimes show how land has been treated. And the planning history will show whether any change of use was ever applied for.

Photographs matter more than people expect. Dated images showing lawn, planting and domestic use over a period are the most direct evidence that land has functioned as garden, and they are also what you need if you are relying on immunity from enforcement, a subject covered in enforcement time limits for permitted development breaches.

Then measure properly. Produce a plan showing the curtilage boundary, the original dwellinghouse footprint, every existing building, enclosure and container with its footprint area, and the arithmetic of the 50 per cent calculation. That single drawing answers most of what an officer will ask.

Where a certificate settles the point

A professional view on curtilage is an opinion. The only formal way to establish that works or a use are lawful is a Lawful Development Certificate, under section 192 of the Town and Country Planning Act 1990 for something proposed and section 191 for something that already exists.

For a disputed curtilage, a section 192 application is the sensible step before building. It is decided on the legal and factual position rather than on planning merits, a positive certificate binds the authority, and the fee is a fraction of the cost of taking a building down.

Set the case out as you would any legal argument: the curtilage plan, the evidence of use, the measured coverage calculation and the reasoning. A Planning Statement structure works well for it. Other alterations have their own separate regimes, and external works are a good example, as painting and external alterations under Part 2 shows.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it, and remember that only a Lawful Development Certificate formally confirms that works are lawful.

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