What is a side return extension?
A side return extension fills the narrow passage that runs alongside the back addition of many Victorian and Edwardian terraced houses. It widens a galley kitchen into a proper kitchen-diner, usually with a sloping glazed roof to keep the room bright.
How much does a side return extension cost in Dulwich?
In Dulwich, a side return extension typically costs £3,000–£4,300 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £36,000–£51,500. That range is adjusted for London, where domestic building work typically costs around 30% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £24,000–£34,500 |
| Typical project (12 m²) | £36,000–£51,500 |
| Larger project (17 m²) | £51,000–£73,000 |
| Rate per m² | £3,000–£4,300 |
The biggest cost drivers are:
- Glazed roof specification
- Access through the house for materials
- Moving drains and soil stacks
- Party wall surveyor fees
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a side return extension in Dulwich?
Approvals for a side return extension in Dulwich follow the rules for England. In England a side return infill is treated as a side extension. It may be permitted development if it is single-storey, no more than 4 metres high and no wider than half the original house, but not in a conservation area. Because side returns sit on the boundary, party wall notices are almost always needed.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
On a typical side return extension we handle:
- Foundations and drainage, including any build-over agreement
- Floor levelling, heating and electrics
- Drawings and planning or permitted development check
- Building control sign-off
- Steel beams to remove the side wall
- Party wall advice and notices
How long does it take?
Expect 10 to 14 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Dulwich
Many London boroughs have conservation areas and detailed design guides, so early design advice saves time at the planning stage.
Dulwich sits in Greater London, about 4 miles south-east of central London. We cover the whole of Dulwich, including postcodes SE21.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side return extensions in Dulwich
How much does a side return extension cost in Dulwich?
In Dulwich, a side return extension typically costs £3,000–£4,300 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £36,000–£51,500. Your fixed price depends on the survey and drawings.
Who approves a side return extension in Dulwich?
Planning matters in Dulwich go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Can I stay in the house?
Usually, though the kitchen will be out of action for several weeks. We plan a temporary kitchen area where possible.
How much space does a side return add?
Typically 1.5 to 2.5 metres of width along the back addition. It often turns a narrow galley kitchen into a family kitchen-diner.
Will I need a party wall agreement?
Almost certainly in England and Wales, because side returns sit on or near the boundary. Notices must be served before work starts, and a party wall surveyor may be appointed if the neighbour does not consent.