Croydon has no householder design guide any more
Much older advice about extending in Croydon points to the Suburban Design Guide, known as SPD2. Ignore it. The council revoked SPD2 in July 2022 and stopped using it to decide applications from 26 July that year. Its chapter on residential extensions went with it. Cabinet said a separate extensions document would follow, but the council's list of planning guidance shows no replacement.
So what do officers judge you against? Mainly Local Plan policy DM10, which the plan itself names as the policy for a household extension. It asks that neighbours don't lose much daylight or sunlight, that nobody is overlooked at close range, and that the roof shape and materials suit the street. There is no 45-degree line and no fixed depth for a back extension, which leaves room for a good design and for an officer to refuse a bad one.
Before paying for full drawings, you can use a householder pre-application service. It is a 20-minute online meeting with an officer, with a short written reply within 20 working days. Nobody visits the house, so send clear photos of the back and of next door.
Every application here needs a flood statement
This one surprises people. Croydon's validation list says every planning application needs a flood risk assessment, even where the land isn't at risk. For a householder job that can be a brief statement and a check of the online flood maps for river, surface water and groundwater risk.
Some places need more than a paragraph. Croydon's resilience team names Boswell Road, Brook Road and Norbury Avenue along the Norbury Brook, the Elmers End area along the Chaffinch Brook, and the culverted stretch under Brighton Road, which is Flood Zone 3a. Croydon also ranks 4th in England for surface water flooding, with South and Central Croydon, Brighton Road and Purley Cross carrying the most homes at risk. In Purley and Kenley the Caterham Bourne, normally dry, can rise from the chalk and run heavily about once every seven years.
Ground matters too. North of the town centre sits on London Clay, which the British Geological Survey calls very susceptible to volume change, shrinking as tree roots draw the water out. If a big tree stands near the new back wall in Thornton Heath or Norbury, the engineer needs to know before the footings are sized. Where trees sit on or next to the site, the validation list wants a tree survey with the application.
Picking the right type for a Croydon house
Semis and terraces make up nearly half the borough's homes, so start with what goes on the back of them.
Single-storey rear. The easy win on a semi in Coulsdon or a terrace in Selhurst. Without an application you can go 3 metres from the original back wall, or 4 metres on a detached house, up to 4 metres high. Prior approval stretches that to 6 or 8 metres, and the council then has 42 days to respond.
Side return. Made for the Victorian terraces around Broad Green, Selhurst and the streets west of the East India Estate, where a back wing leaves a thin yard beside it. Outside a conservation area it often fits the side extension rules.
Kitchen. Most Croydon extensions end up as a kitchen. On a north-facing terrace garden, a roof lantern or glazed strip does more for the room than an extra half metre of floor.
Wrap-around. The usual plan on a Victorian terrace with an outrigger, joining the side return to a rear addition. Because the side leg runs past the side wall, it needs permission in any conservation area.
Open plan. Taking out the back wall of a London Clay terrace puts the load on a steel beam and two pads. Those pads deserve as much care as the new trench footings.
Two-storey. Popular on the interwar semis of New Addington and around Rickman Hill, where a garage at the side tempts people to build over it. Expect the officer to test it against DM10 for light and outlook next door.
Ground-floor bedroom. Big plots in Kenley and Purley have room for it. Plan level access from the drive early, because the hillside roads there rarely give it for free.
Home office. With small back gardens on the older estates, a room joined to the house usually beats a cabin that eats half the lawn.
Planning. Check three things first. Is the home a flat? Flats get no permitted development. Does a conservation area boundary take in your street? Is it on Chatsworth Road?
Cost and value. No figures from us. Deeper footings near trees on clay, a flood statement or a heritage statement in Upper Norwood all change the job, and a builder has to see it.
Conservation areas, the Norbury Estate and Chatsworth Road
In Croydon's 21 conservation areas the national rules shrink. Side extensions, anything over one storey at the back and any cladding all need planning permission, and the larger prior approval route is closed. Local conservation guidance then sets the tone. A single-storey rear extension is generally acceptable if it stays subordinate to the house. A two-storey rear extension is unlikely to be accepted, because of overshadowing. Front extensions are generally unacceptable, and a side extension should sit well back from the front wall, or may be refused outright where the gap between houses is part of the street's character.
The Norbury Estate is tighter still. Its appraisal generally rules out front, side and roof extensions. Back gardens on the eastern half average about 14 metres, so a long extension also eats a big share of the garden.
Chatsworth Road has an Article 4 direction that removes the right to extend at all without permission. Rear and side extensions, porches, and even new windows and doors need an application. There is no fee for one made only because of the direction.
Where these facts come from
- Croydon Council: supplementary planning documents (SPD2 revocation)
- Croydon Local Plan 2018
- Croydon Local Validation List (May 2026)
- Croydon Customer Advice Note 1: pre-application advice (April 2023)
- Croydon Council: flood risk information (October 2020)
- Croydon Council: Conservation Area General Guidance (2013)
- Croydon Council: Norbury Estate appraisal
- Croydon Council: Chatsworth Road Article 4 further information
- British Geological Survey: swelling and shrinking soils
- GOV.UK: permitted development rights for householders, technical guidance
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Questions people in Croydon ask
I keep reading about SPD2 rules for rear extensions. Do they still apply in Croydon?
No. The council revoked SPD2 in July 2022 and no longer uses it for decisions. Your application will be judged mainly against Local Plan policy DM10, plus the conservation guidance if your street is in a conservation area.
We're nowhere near a river in Shirley. Do we really need a flood risk assessment?
Yes, in some form. Croydon's validation list asks for one with every application. For a house extension a short statement with a check of the online flood maps is often enough.
Can we build two storeys on the back of our house in the East India Estate?
Not as permitted development, because it's a conservation area. The council's conservation guidance says two-storey rear extensions are unlikely to be accepted, so a well designed single storey has a much better chance.
We live in Purley near the Bourne. Anything extra to think about?
The Caterham Bourne is fed by groundwater and runs heavily every few years, and Purley Cross is a Critical Drainage Area. Make sure the flood statement deals with groundwater, and ask your designer about floor levels.