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 Plymouth?
In Plymouth, 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. Building costs in the South West are close to the UK average, so the figures for Plymouth are close to our national guide. 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 |
The main things that change the cost:
- Size and layout
- Kitchen and bathroom
- Cladding and finishes
- Drainage connection distance
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a garden annexe in Plymouth?
Before anything is built in Plymouth, 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
What we take care of:
- Foundations and drainage connections
- Electrics and heating
- External cladding or brickwork
- Planning drawings and application
- Kitchenette and shower room
- Insulated walls and roof
How long does it take?
Build time is typically 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 Plymouth
The South West mixes stone and render cottages with post-war and newer estates, and local materials matter more here when matching an extension.
We work across Plymouth and neighbouring areas such as Paignton, Newton Abbot and St Austell. Postcodes we cover in Plymouth include PL2 and PL4.
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
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about garden annexes in Plymouth
How much does a garden annexe cost in Plymouth?
In Plymouth, 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.
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.
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
Do you build garden annexes in Plymouth?
Yes. We build garden annexes across Plymouth, including postcodes PL2 and PL4. 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.