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 Hertford?
In Hertford, a garden annexe typically costs £1,900–£2,950 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £66,500–£103,000. Prices across the East of England are typically 6% above the UK average for this kind of work, which is reflected in the range for Hertford. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £45,500–£71,000 |
| Typical project (35 m²) | £66,500–£103,000 |
| Larger project (49 m²) | £93,000–£144,500 |
| Rate per m² | £1,900–£2,950 |
The main things that change the cost:
- Drainage connection distance
- Access for materials
- Kitchen and bathroom
- Heating type
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 Hertford?
The approval route for Hertford 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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
On a typical garden annexe we handle:
- Kitchenette and shower room
- External cladding or brickwork
- Insulated walls and roof
- Foundations and drainage connections
- Glazed doors and windows
- Planning drawings and application
How long does it take?
Allow 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 Hertford
Across the East of England, 1930s and post-war semis, newer estates and rural cottages all feature, each with different extension and loft options.
We work across Hertford and neighbouring areas such as Hoddesdon, Welwyn Garden City and Hatfield. Postcodes we cover in Hertford include SG13.
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
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
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about garden annexes in Hertford
Who approves a garden annexe in Hertford?
Planning matters in Hertford go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How long does it take?
Typically 10 to 16 weeks on site.
Can an annexe be rented out?
Not without further planning permission, as that would make it a separate dwelling.
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.
How much does a garden annexe cost in Hertford?
In Hertford, a garden annexe typically costs £1,900–£2,950 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £66,500–£103,000. Your fixed price depends on the survey and drawings.