House extension plans for a Purley home cost £645 drawings + £150 survey (£795 total) with us, fixed. That covers the measured survey, existing and proposed drawings, the application pack and submission to Croydon. Croydon's householder fee of £548 is paid to the council and shown separately on your quote.
On this page
- Which rules does Croydon use for a Purley extension now?
- Can I extend a detached Purley house without planning permission?
- What changes on the Webb Estate or in Upper Woodcote Village?
- Does the Brighton Road local heritage area need extra consent?
- Why does Croydon want a flood statement for a house on a hill?
- How long does Croydon take, and what follows approval?
- Frequently asked questions
What varies in Purley is not the fee but the route. Many Purley houses are detached and sit on large, sloping plots, so a good share of extensions can go ahead without a planning application at all. The ones that cannot usually turn on two things: whether the house is inside a conservation area, and how the extension sits against its neighbour.
Which rules does Croydon use for a Purley extension now?
Many Purley owners still find references online to Croydon's Suburban Design Guide, with its diagrams for rear and side extensions. Croydon revoked that guide on 26 July 2022 (Croydon Council). Advice built on its numbers is out of date.
Today an extension that needs permission is judged mainly against policy DM10 of the Croydon Local Plan. A Croydon committee report from April 2026 sets out the tests officers apply: the scale, height and massing should respect the pattern of the area, the design should suit its local context, and neighbours' amenity should be protected (Croydon Planning Sub-Committee, 9 April 2026). A revised Croydon Local Plan has been through examination; we check its status when we start your job, because its weight in decisions grows as it nears adoption.
Without fixed depths to aim at, the drawing has to make the case. On a Purley plot that means showing the neighbours' nearest windows, the fall of the land and the gap to each boundary, so the officer can see the extension does no harm.
Can I extend a detached Purley house without planning permission?
Often, yes. A single-storey rear extension to a detached house is permitted development up to 4 metres deep, and up to 8 metres through the larger home extension prior approval, where neighbours are consulted (MHCLG technical guidance). A side extension can also be permitted development if it is single storey and no wider than half the original house.
Two limits catch Purley owners. First, the "original house" means the house as first built or as it stood on 1 July 1948, so a garage wing or conservatory added in the 1980s already uses up part of the allowance. Second, the house must not be in a conservation area for some of these rights to apply. Our permitted development checker runs through both questions in a few minutes. If the answer is yes, a certificate of lawfulness proves it before you build (what a certificate costs); if the extension is deeper, see our prior approval guide.
What changes on the Webb Estate or in Upper Woodcote Village?
Two of Croydon's 21 conservation areas are in Purley: The Webb Estate and Upper Woodcote Village (Croydon conservation areas directory). The Webb Estate is the Edwardian garden suburb laid out by William Webb, with large houses set in wide, planted plots.
Inside a conservation area, side extensions and two-storey rear extensions need a planning application, and any extension is judged on whether it preserves or enhances the area's character. Croydon's validation list also asks for a heritage statement whenever a heritage asset is affected (Croydon validation list, May 2026). On the Webb Estate, the gaps between houses and the planting in front of them are a large part of that character, so a wide side extension that closes a gap gets far closer scrutiny than one at the back. What a heritage statement contains, and what it costs on its own, is set out in our heritage statement post; if your house needs one, we quote it with the drawings so you see the total before we start.
Does the Brighton Road local heritage area need extra consent?
No. Croydon lists Brighton Road (Purley) as a local heritage area, but the council states there are no additional consent requirements in local heritage areas and permitted development rights are not affected (Croydon local heritage areas). The difference matters when you need a full application anyway: Croydon's validation list treats a local area of special character as a heritage asset, so the application should include a short heritage statement explaining why the design fits.
Why does Croydon want a flood statement for a house on a hill?
Croydon is unusual: it asks for a flood risk assessment with every application, even outside flood risk areas. For a householder extension this is short. It is a brief statement, a check of the online flood maps and proportionate measures such as a water butt or permeable paving (Croydon validation list). Applications without one are held up at validation, so we confirm at the quote stage whether your house needs one and what it costs, before anything is drawn. A full flood risk assessment, needed only in a flood zone, is a separate fixed fee.
The same list asks for photographs in a separate confidential document, a 1:1250 location plan showing two adjoining streets, long and short sections for extensions, and no "do not scale" notes on the drawings. On a Purley slope, the sections do real work: they show how far the extension rises above the neighbour's garden.
How long does Croydon take, and what follows approval?
Croydon writes within 5 working days if anything is missing, and aims to decide 8, 13 or 16 weeks after validation depending on the application (Croydon Council). A householder extension falls in the shortest band.
After approval your builder needs building regulations drawings and usually structural calculations for steels where walls are opened up. Our planning and building regulations package covers all three at one fixed fee; the package cost explained sets out how. More Croydon detail is on our Croydon page, and our Croydon planning drawings page covers other projects in the borough. See our house extensions page for the service itself.
Frequently asked questions
Does the price change for a large detached house in Purley? No. £645 drawings + £150 survey (£795 total) is our published price for the service. If a house is unusually large or complex, we tell you before the survey, not after.
Is the Suburban Design Guide still used in Croydon? No. It was revoked on 26 July 2022. Extensions are judged against the Local Plan's design policy DM10 and the London Plan.
My road is in the Brighton Road local heritage area. Do I lose permitted development rights? No. Croydon says local heritage areas add no consent requirement and leave permitted development rights unchanged.
Do I really need a flood statement in Purley? Yes, if you make a planning application. Croydon asks for one with every application; for an extension outside a flood zone it is a short document, and we tell you at the quote stage whether it is in our fee or a separate one.
If the application goes through the Planning Portal, the Portal adds its own service charge: nothing, £99 or £149 including VAT, depending on the application type and complexity, paid to the Portal at submission and not normally refunded with a council fee (Ashford Borough Council, Planning Portal service charges, 11 September 2026). It is not ours and not the council's. Other submission routes exist; where your council accepts one without a charge, we can use it.
