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A wrap around extension combines a side return infill with a rear extension, and those two elements sit under different permitted development conditions. Treating the scheme as one project is the most common planning error made with this design.
The rear element usually survives local restrictions. The side element frequently does not, and it is the side element that determines whether you need a full application. A wrap around extension is therefore assessed twice, even though it gets built once.
Quick answer: A wrap around extension is a side return infill combined with a rear extension. Side extensions are removed from permitted development entirely in conservation areas, while rear extensions of 3 metres on attached houses and 4 metres on detached ones generally survive. This means a wrap around in a conservation area always needs a full planning application, and outside one, both elements must satisfy their own separate conditions.
What Permitted Development Conditions Apply to Each Half?
Each element carries its own limits, and both must be satisfied at once.
The rear element allows 3 metres beyond the original rear wall on an attached house, or 4 metres on a detached one, with a maximum height of 4 metres. The 6 and 8 metre prior approval route can extend that, currently costing £249.
The side element is more restricted. It must be single storey, and it must not exceed half the width of the original house. There is no prior approval route for a side extension at all.
Both count towards the same overall limit: all buildings together must stay within 50 percent of the curtilage of the original house.
Why Does the Side Element Decide the Planning Route?
Because side extensions of any size are removed from permitted development on designated land, which includes conservation areas.
The rear element generally survives that removal, reducing to 3 metres on all house types including detached. The side element has no equivalent fallback.
The practical consequence is straightforward. Inside a conservation area, a wrap around extension requires a full householder application regardless of how modest it is. You cannot build the rear half under permitted development and the side half under something else, because they form a single building.
Do Croydon Conservation Areas Remove Wrap Around Extension Rights?
Yes, within the designated areas, and Croydon has somewhere in the region of 20 to 24 of them depending on which count you use.
Designated areas include Central Croydon, Church Street, Broad Green and Selhurst, Park Hill, Sanderstead, Upper Woodcote, the Webb Estate, Addington Village, Forestdale, Chatsworth Road, The Waldrons and Kenley Aerodrome, with further control in Addiscombe, South Norwood and Upper Norwood. The Webb Estate carries particularly strict controls.
The majority of Croydon’s residential stock sits outside those boundaries, which is why the borough is more permissive than most inner London authorities. Experienced Croydon Architects check the address against the boundary before anything else, because the answer changes the entire route.
Which Croydon Article 4 Directions Affect Extensions?
Croydon has no borough wide Article 4 direction for standard householder work, but it operates targeted directions inside specific conservation areas.
The Chatsworth Road direction is the clearest example. It took effect on 21 January 2016, and as a result planning permission is required for:
- The extension, improvement or other alteration of a dwelling house
- All alterations to the roof
- The construction of a porch outside any external door
- Hard surfaces within the curtilage
- Gates, fences, walls or other means of enclosure
- A new means of access to the highway
- Painting the exterior of any building
Comparable directions operate at The Waldrons and Kenley Aerodrome. Separately, the borough controls conversion of a house to a small house in multiple occupation in designated wards, and office to residential change of use in parts of the town centre.
Conservation area status and Article 4 status need checking separately, since clearing one tells you nothing about the other.
What Is Changing in Croydon Right Now?
The council announced a conservation area review in December 2025, with nine areas under consideration for designation, reportedly including Sanderstead Village and the Civic Quarter.
If your property sits near one of those, the position could change during your design period. That is worth confirming before committing to a permitted development route, since designation would remove the side element’s fallback and turn the project into a full application.
How Does Croydon’s Housing Stock Affect a Wrap Around?
Croydon spans two quite different conditions, and the design answer differs between them.
Victorian and Edwardian terraces through Thornton Heath, South Norwood and Addiscombe have the classic narrow side return, typically a metre to a metre and a half wide. Infilling it adds only around five to eight square metres, but it converts a galley kitchen into a proper room, which is the real gain.
Interwar semis and detached houses in Purley, Sanderstead, Shirley and Coulsdon sit on more generous plots. There the constraint is usually design and amenity policy rather than available space, and a substantial rear extension may be viable without a wrap at all.
Sloping sites across the southern hills add a further variable, since level changes affect both the structural design and the threshold arrangement.
What Does a Wrap Around Need Technically That a Rear Extension Does Not?
Two structural openings rather than one, and a corner condition where they meet.
Removing both the rear wall and the side return wall means two beams and a junction that has to carry loads from two directions. That is more engineering than a straightforward rear extension, and the calculations go to Building Control under Part A.
Drainage frequently complicates the side return specifically, because the existing soil stack and gully are often located exactly where the new floor needs to go. Relocating them fixes falls beneath the slab, and those decisions are permanent once concrete is poured.
Daylight is the third. A wrap around creates a deeper plan, which pushes the middle of the house further from any window. A rooflight running the length of the side return is generally the most effective response, since top light reaches further into a plan than a vertical window of the same area.
What Should You Confirm Before Designing a Wrap Around?
Four checks, all free, and all capable of changing the design rather than merely informing it.
Confirm whether the address sits inside a conservation area, then separately whether an Article 4 direction applies to the street. Establish whether the property is a house rather than a flat, since flats have no permitted development rights for extensions at all. Locate the original rear wall from the planning record, because the rear depth allowance is measured from there rather than from the current building. Then add up existing outbuildings against the 50 percent curtilage limit.
Croydon granted 87.3 percent of the householder applications it decided across 2025 Q2 to 2026 Q1, which puts it in the middle of the London range. The borough is not unusually difficult. It is simply a borough where the answer depends entirely on which side of a boundary line your house sits.
