What is a wraparound extension?
A wraparound extension combines a side return and a rear extension into one L-shaped addition. It gives the largest possible ground floor, often creating an open-plan kitchen, dining and living space across the whole width of the house.
How much does a wraparound extension cost in Streatham?
In Streatham, a wraparound extension typically costs £2,850–£4,150 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £80,000–£116,000. Building costs in London run about 30% above the UK average, and the figures for Streatham are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £57,000–£83,000 |
| Typical project (28 m²) | £80,000–£116,000 |
| Larger project (39 m²) | £111,000–£162,000 |
| Rate per m² | £2,850–£4,150 |
The biggest cost drivers are:
- Drainage changes
- Party wall surveyor fees for one or both neighbours
- Steelwork and propping of the existing house
- Access for materials on terraced streets
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a wraparound extension in Streatham?
Approvals for a wraparound extension in Streatham follow the rules for England. In England a wraparound extension combines side and rear elements, which normally takes it outside permitted development, so a householder planning application is made.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
We check this for your address before design work starts, so there are no surprises later.
What we handle
The work we manage on a wraparound extension:
- Removal of internal and external walls
- Party wall notices and surveyor liaison
- Building control completion
- Underfloor heating option, electrics and plastering
- Design and planning application
- Structural engineer’s design for steels and supports
How long does it take?
Allow 12 to 18 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Streatham
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
Our Streatham coverage includes postcode districts SW16, and we also work in nearby places such as Balham, Tooting and Clapham.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about wraparound extensions in Streatham
Is a wraparound worth it?
It gives the biggest ground-floor space without going upwards. Whether it adds value depends on your street and house, so we suggest checking local sale prices before committing.
How much does a wraparound extension cost in Streatham?
In Streatham, a wraparound extension typically costs £2,850–£4,150 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £80,000–£116,000. Your fixed price depends on the survey and drawings.
Will both neighbours be affected?
Usually only the neighbour on the side return side, but rear foundations near either boundary can trigger party wall notices.
Can we keep a separate living room?
Yes. Many clients keep the front room separate and open up only the back of the house.
How long does a wraparound extension take in Streatham?
Typically 12 to 18 weeks on site. Design and approvals beforehand usually take 3 to 4 months.