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 Wembley?
In Wembley, a garden annexe typically costs £2,350–£3,650 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £82,000–£128,000. Building costs in London run about 30% above the UK average, and the figures for Wembley are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £56,500–£87,500 |
| Typical project (35 m²) | £82,000–£128,000 |
| Larger project (49 m²) | £115,000–£179,000 |
| Rate per m² | £2,350–£3,650 |
Your quote will depend mainly on:
- Drainage connection distance
- Heating type
- Kitchen and bathroom
- Access for materials
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a garden annexe in Wembley?
Here is how the rules work for a garden annexe 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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
What we take care of:
- Insulated walls and roof
- Glazed doors and windows
- Foundations and drainage connections
- Electrics and heating
- Kitchenette and shower room
- Building control sign-off
How long does it take?
Build time is typically 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 Wembley
Many London boroughs have conservation areas and detailed design guides, so early design advice saves time at the planning stage.
Wembley sits in Greater London, about 8 miles north-west of central London. We cover the whole of Wembley, including postcodes HA0.
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 pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about garden annexes in Wembley
How long does it take?
Typically 10 to 16 weeks on site.
Who approves a garden annexe in Wembley?
Planning matters in Wembley go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Can it be accessible?
Yes. Level access, wider doors and a wet room can be designed in.
How much does a garden annexe cost in Wembley?
In Wembley, a garden annexe typically costs £2,350–£3,650 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £82,000–£128,000. Your fixed price depends on the survey and drawings.
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.