The angles the planners draw from next door's window
Chichester District Council still works from its own Planning Guidance Note 3 on alterations and extensions, last revised in September 2009. It's advisory, but the officers use it. There's no fixed limit on how far back you can go. Instead they take a line from the middle of your neighbour's nearest ground floor habitable window. For a single storey addition that line is drawn at 60 degrees. For two storeys it tightens to 45. If next door has already built out at the back, the 60 degree line comes from their first floor window instead.
Sketch those lines on a plan of your garden before you fall in love with a layout. They usually decide the depth.
The same note asks for a gap. Two-storey and first floor side additions should normally sit at least one metre in from the shared boundary, so a row of detached houses doesn't fuse into a terrace. It wants about 10 metres of garden left behind the house, though it accepts a modest ground floor addition can take you under that. And it is wary of flat roofs. A flat-roofed rear addition needs more justification, and a flat roof at first floor will normally be resisted.
Roof pitch gets real numbers too. Slate generally wants at least 26.5 degrees, peg tiles are usually fine at 42.5, and the guidance says to avoid 45 because it lacks visual interest. Match the roof on the house.
Where the Lavant runs, and what's under it
The Lavant is a chalk stream that mostly flows in winter, and it runs in culverts under the city. The Environment Agency's flood warning area for it covers central Chichester, including Whyke and the area round Chichester College. The council's flood study notes that groundwater flooding here can last for several weeks.
If your house is in Flood Zone 2 or 3, the application needs a flood risk assessment. For a householder job that follows the Environment Agency's standing advice, which wants the new floor at least 600 millimetres above the estimated flood level, or flood-resistant construction to that height. Check the flood map for planning before the architect starts drawing.
The ground varies too. Much of the coastal plain is brickearth, a wind-blown silt, lying over chalk, and the British Geological Survey records solution pipes in the chalk across the district. North of the city there are Lavant gravels, and made ground round the edges. A trial hole before pricing the footings is money well spent.
Picking a type for a Chichester house
Every type below has its own full guide.
Planning first. Inside the city conservation area, the Article 4 direction takes away the right to extend where the work fronts a road, open space or waterway, on top of the usual conservation area limits. In the South Downs National Park, the park authority decides instead of the district.
Single-storey rear. On an East Broyle detached house, 4 metres beyond the original back wall needs no application, or 8 with prior approval. A semi gets 3, or 6 with approval. The council's 60 degree line still matters if you go to full planning.
Kitchen. The usual reason people extend here. Near the harbour, the joint guidance is wary of reflective glass and big picture windows, so a kitchen there may need smaller openings than you'd draw in the city.
Side return. Somerstown and Whyke have the terraces with a narrow side passage. Both sit in the conservation area, where no side addition is permitted development, so plan on a full application.
Open plan. Knocking through to a new room means a steel on new pads. On brickearth over chalk, let the engineer see a trial hole before he sizes them.
Two-storey. This is where the 45 degree line and the one-metre side gap both bite. Summersdale's Edwardian semis often have room down the side, but keep the new ridge below the old one.
Wrap-around. The side leg always takes it into a planning application. It suits the larger 1960s and 1970s plots north-west of the city better than a tight Victorian terrace.
Ground-floor bedroom. A sensible choice on the bungalows of The Drive and the villages. In a flood zone, raising the floor helps with the assessment but makes level access harder, so design the ramp and the threshold together.
Home office. An attached study keeps you warm and on the house's broadband. In the city conservation area the Article 4 direction covers outbuildings too, so a cabin by the road isn't the easy option it looks.
Cost and value. We don't print prices. A flood assessment, deeper footings in chalk or flint walling to match a Fishbourne cottage can each move the number a long way. Get three builders to see the site.
Round the harbour, a different rulebook
Chichester Harbour is a National Landscape, and the district and Havant adopted joint guidance for it in May 2017. For a big addition it suggests no more than a 50% increase on the original footprint, and no more than 25% on the silhouette of any side seen from the wider landscape, which includes from the water. Being protected land, it also loses the permitted side additions and the permitted two-storey rear ones.
It cares about looks as much as size. Dark roofs, muted colours, timber, flint and brick are favoured. New England style cladding is unlikely to be accepted, and the guidance prefers more building than window. The Harbour Conservancy comments on around 300 applications a year and gives advice before you apply. I'd use it.
Where these facts come from
- Design Guidelines for Alterations to Dwellings and Extensions, 2009 (Chichester District Council)
- Joint Chichester Harbour AONB SPD, 2017 (Chichester District Council)
- Chichester Harbour Conservancy: planning
- Chichester District Council: Article 4 directions
- Article 4 directions for Chichester Conservation Area, Cabinet appendix (2018)
- Level 1 Strategic Flood Risk Assessment, 2018 (Chichester District Council)
- Chichester on the River Lavant flood warning area (Environment Agency)
- Flood risk assessment standing advice (GOV.UK)
- Chichester and Bognor sheet explanation (British Geological Survey)
- Permitted development for householders, technical guidance (GOV.UK)
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Questions people in Chichester ask
How far back can I build before my neighbour's window becomes a problem?
The council doesn't set a fixed depth. Its 2009 guidance draws a 60 degree line from the middle of the neighbour's nearest ground floor habitable window for a single storey, and 45 degrees for two storeys. If the new wall crosses that line, expect a refusal or a redesign.
Our house in Whyke is near the Lavant. Will it complicate an extension?
Look up the flood map for planning first. In Flood Zone 2 or 3 you'll need a flood risk assessment with the application, and the floor of the new room will normally need raising or building to resist flooding. Groundwater can sit high for weeks after a wet winter, which affects drainage and footings too.
We live near the harbour. Is there a limit on how big we can go?
The joint harbour guidance points to no more than a 50% increase on the original footprint and 25% on any elevation seen from the wider landscape. It's guidance, not a ceiling, and the officers weigh how the house sits in the view.
Can a two-storey side addition go right up to our boundary?
Normally not. The council asks for two-storey and first floor side additions to be set in at least one metre from the shared boundary, so neighbouring houses don't join up into a terrace.