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 Greenford?
In Greenford, 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 Greenford 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 |
What moves the price most:
- Cladding and finishes
- Access for materials
- Heating type
- Drainage connection distance
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 Greenford?
Before anything is built in Greenford, we confirm which approvals apply 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
The work we manage on a garden annexe:
- Kitchenette and shower room
- Glazed doors and windows
- Building control sign-off
- Insulated walls and roof
- Electrics and heating
- External cladding or brickwork
How long does it take?
Build time is typically 10 to 16 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Greenford
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
Our Greenford coverage includes postcode districts UB6, and we also work in nearby places such as Northolt, Southall and Ealing.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 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
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about garden annexes in Greenford
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
Can an annexe be rented out?
Not without further planning permission, as that would make it a separate dwelling.
Who approves a garden annexe in Greenford?
Planning matters in Greenford 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 Greenford?
In Greenford, 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.