Which permitted development rights are lost on designated land

Permitted development conservation area rights are not simply tightened. Specific limbs of specific classes are switched off, and the pattern is uneven: side extensions disappear entirely, dormers disappear entirely, outbuildings shrink only in the far part of the garden, and cladding becomes unlawful anywhere on the house. Knowing which limb applies to your proposal saves a wasted set of drawings.

The term the Order uses is article 2(3) land, and it covers more than conservation areas. If your property sits in any of those designations, work through the list below before the design starts.

What Article 2(3) land covers

Article 2(3) of the Town and Country Planning (General Permitted Development) (England) Order 2015 defines the designated land to which the tighter limits apply:

• Conservation areas.
• National Parks.
• Areas of outstanding natural beauty, now branded National Landscapes, with the statutory designation unchanged.
• The Broads.
• World Heritage Sites.
• Land in an area specified by ministers for the purposes of the countryside legislation, a narrow category that rarely arises.

Note what is not on that list. Sites of special scientific interest, Green Belt, Tree Preservation Orders, Archaeological Priority Areas and local wildlife designations are not article 2(3) land, and they do not trigger these restrictions. They can bring other consequences, and some classes exclude sites of special scientific interest separately, but the article 2(3) limits are the ones set out below.

Listed buildings are also a separate question. Permitted development rights still exist for a listed building in many respects, and listed building consent is a different consent with a different test, needed in addition to planning permission wherever the works affect the building's character as a building of special interest.

Side extensions and cladding removed from Class A

Class A of Part 1 permits the enlargement, improvement or other alteration of a dwellinghouse. On article 2(3) land three things change.

No extension beyond a wall forming a side elevation of the original dwellinghouse. That removes side extensions outright, including the narrow infill between a house and its boundary that is the most common householder project in a terrace or semi.

No extension of more than one storey beyond the rear wall of the original dwellinghouse. Two-storey rear extensions are therefore out, however modest.

No cladding of any part of the exterior with stone, artificial stone, pebble dash, render, timber, plastic or tiles. This one surprises people, because it applies to the whole house rather than to the extension, and rendering a rear elevation in a conservation area needs planning permission.

The larger home extension prior approval procedure, which allows single-storey rear extensions of up to 8 metres on a detached house and 6 metres otherwise, is also unavailable on article 2(3) land. The baseline limits of 4 metres and 3 metres apply instead, with no route to go further without a full application.

So in a conservation area the realistic Class A project is a single-storey rear extension within the baseline depth limits, with no side element and no new cladding.

Outbuilding limits tightened under Class E

Class E covers buildings and enclosures incidental to the enjoyment of the dwellinghouse. The article 2(3) restriction is specific and often misread.

Where any part of the proposed building sits more than 20 metres from any wall of the house, the total area of ground covered by buildings, enclosures, pools and containers more than 20 metres from the house must not exceed 10 square metres.

Read carefully, that leaves the inner part of the garden alone. A garden room within 20 metres of the house is governed by the ordinary Class E limits on height, position and the 50 per cent curtilage test, which is explained in the 50 per cent curtilage rule for garden outbuildings. It is only the far end of a long garden where the 10 square metre cap bites.

Measure the 20 metres from the nearest wall of the house, and remember that the cap is cumulative across everything already out there. An existing shed of 8 square metres at the bottom of the garden leaves 2 square metres.

Roof extensions excluded under Class B

Class B permits an enlargement of a dwellinghouse consisting of an addition to or alteration of its roof, which is the class that delivers dormer windows and rear roof extensions.

Class B development is not permitted at all on article 2(3) land. Not limited, not conditional, not subject to prior approval. A dormer in a conservation area needs planning permission, full stop.

Class C, which covers other alterations to a roof that do not extend beyond the plane of the existing slope, is still available. That is the class rooflights sit in, and the usual conditions apply, including the restriction on the principal elevation where it fronts a highway and the requirement that the alteration does not protrude more than 150 millimetres beyond the roof plane.

In practice conservation officers care a great deal about rooflights on front slopes, and many conservation areas have Article 4 directions removing Class C as well. Check before ordering anything.

Where permission is needed, the application has to engage with the character of the area, and a short Heritage Statement identifying the significance of the area and the effect of the proposal is what the conservation officer will look for.

Solar, antennas and flues restricted

Three smaller classes carry article 2(3) limits that catch retrofit projects.

Solar panels on a dwellinghouse, under Part 14, must not be installed on a wall forming the principal elevation of the house where that wall fronts a highway when the property is on article 2(3) land. Roof-mounted panels remain available subject to the general limits on projection and position, though in a conservation area the siting still needs thought.

Flues for biomass or combined heat and power, under Part 1 Class G, must not be fitted on a wall or roof slope forming the principal elevation of the house where that elevation fronts a highway. The same applies to a side elevation fronting a highway.

Antennas and satellite dishes, under Part 1 Class H, are limited in number and size everywhere, and on article 2(3) land an antenna must not be installed on a chimney, wall or roof slope facing and visible from a highway, with further restrictions in conservation areas and World Heritage Sites.

Air source heat pumps carry their own conditions on siting and noise rather than an article 2(3) exclusion, and those conditions have been amended, so read the current text of the relevant class rather than an older summary.

Hard surfacing is treated differently again. Class F is not restricted by article 2(3), and the permeable surfacing condition for front gardens over five square metres applies everywhere, as set out in front garden paving, permeable surfaces and Class F.

World Heritage Sites and the Broads

World Heritage Sites and the Broads sit in article 2(3) alongside conservation areas and attract the identical restrictions, and both are easy to overlook.

World Heritage Site boundaries are wide in some places and the designation is not always obvious from a property's address. A house in a village several miles from a famous monument can still be inside the inscribed area or its buffer zone, and the article 2(3) limits apply within the site itself.

The Broads is an executive area with National Park equivalence, and properties within it are on article 2(3) land even though the area is not called a National Park.

In a conservation area there is one further control worth knowing. Demolition of a building, including a boundary wall above the relevant height, can require planning permission for relevant demolition, so taking a structure down is a separate question from building something new.

Trees are controlled separately too. Works to a tree in a conservation area require six weeks' written notice to the council under section 211 of the Town and Country Planning Act 1990, whether or not a Tree Preservation Order applies.

Checking the designation before you design

Run these checks before the first drawing:

1. Search the national planning data service for conservation area, National Park, National Landscape and World Heritage Site boundaries at the property's coordinates.
2. Open the council's own constraints map, which carries the definitive local boundary and usually the conservation area appraisal.
3. Ask the council for the list of Article 4 directions affecting the street, because directions are often street-specific and remove rights that article 2(3) leaves in place.
4. Check whether the building is listed, and whether it sits within the curtilage of a listed building, which is a separate and stricter position.
5. Check for a Tree Preservation Order and for trees in the conservation area that will need a section 211 notice.
6. Where the conservation area has a published appraisal and management plan, read the sections on extensions, materials and boundary treatments, since they tell you what the conservation officer will say.

Boundaries do not follow property lines. A conservation area edge can run down the middle of a garden, and a proposal in the designated part is restricted while the same proposal twenty metres away is not. Get the boundary from the mapping rather than from a neighbour.

Where permitted development is unavailable, a householder planning application is the route, and a short Planning Statement addressing the area's character, the local design guidance and the effect on neighbours is usually enough. And if you need certainty that works already carried out were lawful, a Lawful Development Certificate under section 191 or 192 of the Town and Country Planning Act 1990 is the only formal way to establish it.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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