Extending in a conservation area: Chichester and Arundel

By James Reilly, Swanbourne Construction Ltd · Published 15 October 2026 · Planning rules and local designations checked October 2026

You can extend a house in a conservation area, but fewer things are permitted development and design is judged more closely. In a conservation area — and in the South Downs National Park and the Chichester Harbour National Landscape — side extensions, rear extensions of more than one storey, the 6m and 8m larger home extension route, cladding, and every kind of dormer or roof enlargement need planning permission. A single-storey rear extension within the standard 3m or 4m depth can still be permitted development. Article 4 directions can remove more, and a listed building needs listed building consent for almost anything that affects its character, inside or out.

Chichester District Council has around 85 conservation areas including those in the National Park; Arun District Council says it has 29, including Arundel, Felpham, Rustington, several in Bognor Regis and Littlehampton, and Aldwick Bay. So this is not a rare situation around here. It is the normal one for a lot of the best houses on our patch.

What changes in a conservation area

A conservation area, a National Park and a National Landscape are all "Article 2(3) land" in the permitted development order. On that land:

Source: Planning Portal and the permitted development order, as in force October 2026.

Two more things come with a conservation area. Demolishing a building — an old garage, an outhouse, a boundary wall — to make room for an extension can need planning permission in its own right. And most trees are protected by a notice period: you have to give the council six weeks' written notice before cutting down or pruning them, which belongs at the front of the programme, not slotted in around it.

Article 4 directions

An Article 4 direction is a separate decision by the council to remove particular permitted development rights in a defined area — typically for changes to windows, doors, roofs, chimneys, boundary walls and frontages that would otherwise be allowed. They are published, and they vary a great deal from place to place.

• Chichester has Article 4 directions covering the Chichester city conservation area and several others, including Bosham, Boxgrove, Tangmere and West Itchenor. What each one controls is set out in the direction itself, and it is worth reading the one for your area rather than relying on a summary.
• Arun lists conservation-area Article 4 directions only at Craigweil House in Aldwick, plus a direction about houses in multiple occupation covering Marine and Hotham wards in Bognor Regis and River ward in Littlehampton. We have checked the conservation areas at Arundel, Bognor Regis and Felpham and found no Article 4 direction removing householder rights there.

Directions can be made at any time, so we check the address rather than rely on a list. Arun has an online postcode checker for conservation areas, listed buildings and Article 4 directions.

Arundel: who decides?

Arundel catches people out because of the South Downs National Park, which wraps around it. The town itself was left out of the Park when the boundary was drawn, while the castle and its grounds were included, and only part of the wider parish is inside. In practice:

• For most houses in Arundel town, including the conservation area, the planning authority is Arun District Council.
• For property inside the Park boundary, it is the South Downs National Park Authority, which pays close attention to visual impact, dark night skies, glazing and traditional materials.
• Building Control is Arun District Council everywhere in the district, National Park or not.

The Park's own boundary map is approximate, so a property anywhere near the line gets checked with the Authority rather than guessed at. Arundel's conservation area has not had a formal review for many years, and Arun has more recently been adopting appraisals for other areas, so the expectations are best judged from the street itself: its flint, red brick, clay tile, slate and timber windows. Arundel is also built on a hill of chalk, with narrow, steep streets, and both of those shape what an extension costs before anyone draws it — see our page on building in Arundel.

Chichester: inside the walls and out

Chichester is two building markets with a ring road between them. The Chichester City Conservation Area, first designated in 1970 and extended several times since, covers the historic centre, and its character appraisal sets out what makes it what it is: mostly red brick, often with blue-header chequerwork; knapped flint; steep handmade clay tile roofs on older buildings and Welsh slate on later ones; timber sliding sashes; and painted stucco on some of the grander streets. Inside that area, any extension beyond a modest single-storey rear one is an application, the scrutiny of mortars, joinery profiles and roof coverings is close, and nobody honest promises you a quick eight weeks through the conditions.

Outside the ring road — Parklands, Summersdale, Whyke — most houses are not in a conservation area and permitted development works as normal. Our Whyke Close loft conversion was permitted development; the same dormer inside a conservation area would have been an application.

Chichester District Council adopted its Local Plan 2021–2039 in August 2025. Inside the National Park, the National Park Authority is the planning authority, although Chichester District Council processes many of those applications on its behalf under an agency agreement renewed from October 2026. Around the harbour, the Chichester Harbour Conservancy is consulted on applications in the National Landscape.

Listed buildings

A listed building is different again. Listed building consent is needed for any work that affects its character as a building of special interest — and that means the inside as much as the outside, and structures within its grounds. Arun District Council puts it plainly: everything counts, from basement to chimney pots. Doing such work without consent is a criminal offence, and the builder can be liable alongside the owner.

• Listed building consent has no application fee. It sits alongside planning permission rather than replacing it; many extensions need both.
• Allow around eight weeks for a Grade II application, longer for Grade II* or I.
• Near a listed building, even if yours is not listed, planners must consider the effect on its setting.
• Approved Document L allows energy-efficiency requirements to be relaxed where meeting them would unacceptably alter a listed building's character, while still requiring improvement as far as reasonably practicable.

We do not hold a heritage accreditation and will not pretend to. We tell you before anything starts where consent is needed, and say plainly when a job wants a conservation specialist alongside us.

What planners expect

Every authority has its own guidance, but the principles in conservation areas are consistent:

• Subordinate. An extension that is clearly secondary to the house — lower ridge, set back from the main walls, smaller in scale — is far easier to approve than one that competes with it.
• Matching materials. Brick that matches in colour, texture and bond; flint panels with brick quoins where that is the local tradition; clay tile or natural slate at a pitch that suits it. Chichester's design guidance suggests minimum pitches of around 26.5° for slate and 42.5° for peg tile, and says flat roofs need more justification.
• Timber windows that follow the pattern of the house. uPVC on a principal elevation is likely to be resisted.
• Good modern design can be accepted where it is genuinely high quality and clearly distinct — a well-detailed glazed link, for example — rather than a poor imitation of the old.
• Rear elevations are judged less strictly than frontages, which is why most successful conservation-area extensions are at the back.

Pre-application advice from the council is worth paying for on anything significant in a conservation area or near a listed building. It turns a refusal into a conversation.

Practical points for a conservation-area job

• Timescales stretch. Add the application, any pre-application advice, and the time to discharge conditions on materials — samples of brick, tile and mortar are often required before work.
• Materials cost more. Reclaimed or handmade tiles, matched bricks and flint work take longer and cost more than modern equivalents, and the trades who do them well are in demand.
• Access can be the real cost. Central Chichester's controlled parking zone means skip permits and trader bays booked well ahead; Arundel's steep streets mean small plant and hand-carrying.
• Trees. Six weeks' notice to the council before cutting or pruning.

Questions people ask about conservation area extensions

Where these facts come from

• Planning Portal: extensions and designated land.
• Arun District Council: conservation areas.
• Chichester District Council: conservation areas and Article 4 directions.
• Chichester City Conservation Area Character Appraisal.
• South Downs National Park Authority: Arundel.
• Historic England: the National Heritage List.