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 Hendon?
In Hendon, 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. Building costs in London run about 30% above the UK average, and the figures for Hendon are adjusted to reflect that. 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:
- Access through the house for materials
- Length of the side return
- Party wall surveyor fees
- Moving drains and soil stacks
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a side return extension in Hendon?
Before anything is built in Hendon, we confirm which approvals apply in 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.
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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
The work we manage on a side return extension:
- Steel beams to remove the side wall
- Floor levelling, heating and electrics
- Survey of party walls, drains and the existing back addition
- Building control sign-off
- Drawings and planning or permitted development check
- Foundations and drainage, including any build-over agreement
How long does it take?
Allow 10 to 14 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Hendon
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
We work across Hendon and neighbouring areas such as Finchley, Mill Hill and Golders Green. Postcodes we cover in Hendon include NW4.
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 fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed 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 Hendon
How much does a side return extension cost in Hendon?
In Hendon, 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.
Do you build side return extensions in Hendon?
Yes. We build side return extensions across Hendon, including postcodes NW4. Every project starts with a free home visit.
Is a glass roof too hot or cold?
Modern solar-control double or triple glazing reduces glare and heat loss. Building regulations also limit how much glazing you can have unless the design shows it performs well enough.
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.
Does a side return extension need planning permission?
It depends on the design and where you live. In England a side return can sometimes be permitted development, but side extensions in conservation areas and on many terraced streets need an application. We check your house’s rights before designing.