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 the West Midlands?
In the West Midlands, a garden annexe typically costs £1,750–£2,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £61,000–£94,500. Prices in the West Midlands sit near the national average for this kind of work, and the range for the West Midlands reflects that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £42,000–£65,000 |
| Typical project (35 m²) | £61,000–£94,500 |
| Larger project (49 m²) | £86,000–£132,500 |
| Rate per m² | £1,750–£2,700 |
Your quote will depend mainly on:
- Access for materials
- Size and layout
- Kitchen and bathroom
- Cladding and finishes
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 the West Midlands?
The approval route for the West Midlands is set by planning law 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
Handled as part of most garden annexes:
- Kitchenette and shower room
- Planning drawings and application
- External cladding or brickwork
- Glazed doors and windows
- Electrics and heating
- Foundations and drainage connections
How long does it take?
The build itself usually takes 10 to 16 weeks on site. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in the West Midlands
Across the West Midlands, inter-war and post-war semis make up much of the housing, giving good scope for two-storey side extensions and hip-to-gable lofts.
Towns we cover in the West Midlands include Birmingham, Coventry, Wolverhampton, Dudley, Walsall and Solihull.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about garden annexes in the West Midlands
Does a garden annexe need planning permission?
Usually yes if it is used as living accommodation. Outbuildings under permitted development must be incidental to the house, such as a gym or office, not bedrooms.
Can it be accessible?
Yes. Level access, wider doors and a wet room can be designed in.
Do you build garden annexes in the West Midlands?
Yes. We build garden annexes across the West Midlands, including postcodes B1, B10, B11, B12 and B13. Every project starts with a free home visit.
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 the West Midlands?
In the West Midlands, a garden annexe typically costs £1,750–£2,700 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £61,000–£94,500. Your fixed price depends on the survey and drawings.