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 Mangotsfield?
In Mangotsfield, a garden annexe typically costs £1,850–£2,850 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £65,000–£100,000. Prices in the South West sit near the national average for this kind of work, and the range for Mangotsfield reflects that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £44,500–£68,500 |
| Typical project (35 m²) | £65,000–£100,000 |
| Larger project (49 m²) | £90,500–£139,500 |
| Rate per m² | £1,850–£2,850 |
Your quote will depend mainly on:
- Access for materials
- Kitchen and bathroom
- Heating type
- Cladding and finishes
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 garden annexe in Mangotsfield?
The approval route for Mangotsfield 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
The work we manage on a garden annexe:
- Insulated walls and roof
- Electrics and heating
- External cladding or brickwork
- Foundations and drainage connections
- Planning drawings and application
- Glazed doors and windows
How long does it take?
The build itself usually takes 10 to 16 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Mangotsfield
In parts of the South West, protected landscapes and conservation areas shape what can be built, so materials and roof forms are chosen carefully.
If your home is in Mangotsfield or close by in Kingswood, Keynsham and Yate, a free home visit is the first step.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 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 Mangotsfield
Can it be accessible?
Yes. Level access, wider doors and a wet room can be designed in.
Who approves a garden annexe in Mangotsfield?
Planning matters in Mangotsfield go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
How much does a garden annexe cost in Mangotsfield?
In Mangotsfield, a garden annexe typically costs £1,850–£2,850 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £65,000–£100,000. Your fixed price depends on the survey and drawings.