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 Mid Glamorgan?
In Mid Glamorgan, a garden annexe typically costs £1,650–£2,600 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £58,000–£91,000. That range is adjusted for Wales, where domestic building work typically costs around 8% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £39,500–£62,500 |
| Typical project (35 m²) | £58,000–£91,000 |
| Larger project (49 m²) | £81,000–£127,500 |
| Rate per m² | £1,650–£2,600 |
The biggest cost drivers are:
- Drainage connection distance
- Size and layout
- Cladding and finishes
- Access for materials
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 Mid Glamorgan?
The approval route for Mid Glamorgan is set by planning law in Wales. In Wales an annexe with sleeping accommodation usually needs planning permission; outbuildings under permitted development must be incidental to the house.
Building regulations in Wales are set by the Welsh Government. Approval comes from the council’s building control service or a registered building control approver, with inspections during the work and a completion certificate 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:
- Electrics and heating
- Planning drawings and application
- Building control sign-off
- Kitchenette and shower room
- Insulated walls and roof
- Foundations and drainage connections
How long does it take?
Allow 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 Mid Glamorgan
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Towns we cover in Mid Glamorgan include Bridgend, Merthyr Tydfil, Pontypridd, Aberdare, Caerphilly and Maesteg.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 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 Mid Glamorgan
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
How much does a garden annexe cost in Mid Glamorgan?
In Mid Glamorgan, a garden annexe typically costs £1,650–£2,600 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £58,000–£91,000. Your fixed price depends on the survey and drawings.
Who approves a garden annexe in Mid Glamorgan?
Planning matters in Mid Glamorgan 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.
Do I need planning permission for a garden annexe in Mid Glamorgan?
In Wales an annexe with sleeping accommodation usually needs planning permission; outbuildings under permitted development must be incidental to the house.
How long does it take?
Typically 10 to 16 weeks on site.