What is a garden annexe?

A garden annexe is a single-storey building in the garden with its own living space, bathroom and often a kitchenette, used by relatives, older children or guests. Unlike a garden room, it is built as habitable accommodation with foundations, insulation and services.
How much does a garden annexe cost in Rushden?
In Rushden, a garden annexe typically costs £1,700–£2,650 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £59,500–£93,000. Prices across the East Midlands are typically 5% below the UK average for this kind of work, which is reflected in the range for Rushden. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £41,000–£63,500 |
| Typical project (35 m²) | £59,500–£93,000 |
| Larger project (49 m²) | £83,500–£130,000 |
| Rate per m² | £1,700–£2,650 |
What moves the price most:
- Cladding and finishes
- Heating type
- Size and layout
- Drainage connection distance
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a garden annexe in Rushden?
Whether you need planning permission depends on your house and its location in England. In England an annexe used as living accommodation usually needs planning permission. Outbuildings built under permitted development must be incidental to the house, such as a gym or office, not a bedroom.
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 garden annexe we handle:
- Planning drawings and application
- Kitchenette and shower room
- External cladding or brickwork
- Glazed doors and windows
- Insulated walls and roof
- Building control sign-off
How long does it take?
Expect 10 to 16 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Rushden
The East Midlands has a mix of red-brick terraces, inter-war semis and newer estates, so rear extensions and garage conversions are common projects.
Rushden sits in Northamptonshire, about 12 miles east of Northampton. We cover the whole of Rushden, including postcodes NN10.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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 garden annexes in Rushden
Can an annexe be rented out?
Not without further planning permission, as that would make it a separate dwelling.
Will council tax apply?
Annexes can be banded separately, though discounts or exemptions apply in some cases when occupied by family. Check with your council.
How much does a garden annexe cost in Rushden?
In Rushden, a garden annexe typically costs £1,700–£2,650 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £59,500–£93,000. Your fixed price depends on the survey and drawings.
Who approves a garden annexe in Rushden?
Planning matters in Rushden go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How long does it take?
Typically 10 to 16 weeks on site.
