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 Borehamwood?
In Borehamwood, 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 Borehamwood. 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 biggest cost drivers are:
- Cladding and finishes
- Heating type
- Access for materials
- Size and layout
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a garden annexe in Borehamwood?
Approvals for a garden annexe in Borehamwood follow the rules for 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
From survey to sign-off, the job normally involves:
- Kitchenette and shower room
- Glazed doors and windows
- Foundations and drainage connections
- Building control sign-off
- Planning drawings and application
- Insulated walls and roof
How long does it take?
Expect 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 Borehamwood
Across the East of England, 1930s and post-war semis, newer estates and rural cottages all feature, each with different extension and loft options.
Our Borehamwood coverage includes postcode districts WD6, and we also work in nearby places such as Edgware, Mill Hill and Stanmore.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about garden annexes in Borehamwood
How long does it take?
Typically 10 to 16 weeks on site.
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
How much does a garden annexe cost in Borehamwood?
In Borehamwood, 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.
Do you build garden annexes in Borehamwood?
Yes. We build garden annexes across Borehamwood, including postcodes WD6. Every project starts with a free home visit.
Can it be accessible?
Yes. Level access, wider doors and a wet room can be designed in.