What is a single-storey extension?
A single-storey extension is a ground-floor addition, usually at the rear of a house, that enlarges a kitchen, living or dining space. Most are built with cavity walls on concrete foundations and finished with a flat roof and roof lantern or a pitched tiled roof.
How much does a single-storey extension cost in Hendon?
In Hendon, a single-storey extension typically costs £2,550–£3,750 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £51,000–£75,000. The guide for Hendon reflects typical costs in London, roughly 30% above the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £35,500–£52,500 |
| Typical project (20 m²) | £51,000–£75,000 |
| Larger project (28 m²) | £71,500–£105,000 |
| Rate per m² | £2,550–£3,750 |
Your quote will depend mainly on:
- Kitchen, flooring and finishes, which we can include or leave to you
- Floor area and the length of new wall
- Ground conditions and foundation depth
- Roof type and the size of any lantern or roof windows
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 single-storey extension in Hendon?
Here is how the rules work for a single-storey extension in England. In England a single-storey rear extension is often permitted development: broadly up to 3 metres deep on a semi-detached or terraced house and 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary, and covering no more than half the garden. The larger home extension scheme allows up to 6 or 8 metres if you notify the council first and neighbours have a chance to comment. In conservation areas, National Parks and National Landscapes the larger home extension route, side extensions and cladding are not permitted development. Flats and houses whose rights have been removed need a planning application, and listed buildings need listed building consent.
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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
Handled as part of most single-storey extensions:
- First and second fix electrics, heating and plastering
- Structural calculations for steels and lintels
- Foundations, drainage and any build-over agreement
- Doors, windows and roof glazing installed
- Knock-through to the existing house with steel beams
- Measured survey and design drawings
How long does it take?
The build itself usually takes 10 to 14 weeks on site for a typical rear extension, after approvals. Before that, surveys, drawings and approvals usually take 6 to 12 weeks, longer if the council asks for changes.
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
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 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 single-storey extensions in Hendon
Can I stay in the house during the build?
Usually yes. We build the shell before opening up the back wall, so the house stays weathertight for most of the job. There will be a few weeks when the kitchen or back room is out of use.
How long does a single-storey extension take in Hendon?
Typically 10 to 14 weeks on site for a typical rear extension, after approvals. Design and approvals beforehand usually take 6 to 12 weeks.
What is a build-over agreement?
If a public sewer runs within 3 metres of the extension, the water company normally has to agree to the work before it starts. We check sewer records during design and apply where needed.
Do I need planning permission for a single-storey extension?
Not always. Many small rear extensions are permitted development, within limits on depth, height and how much of the garden is covered. The limits depend on which nation you live in and on protected areas such as conservation areas, and flats or houses whose rights have been removed need an application. We check this at the survey and can apply to the council for formal confirmation.
How much does a single-storey extension cost in Hendon?
In Hendon, a single-storey extension typically costs £2,550–£3,750 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £51,000–£75,000. Your fixed price depends on the survey and drawings.