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 Peterborough?
In Peterborough, 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. The guide for Peterborough reflects typical costs in the East of England, roughly 6% above the UK-wide figure. 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:
- Access for materials
- Heating type
- Drainage connection distance
- Size and layout
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 Peterborough?
The approval route for Peterborough 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.
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:
- External cladding or brickwork
- Insulated walls and roof
- Electrics and heating
- Foundations and drainage connections
- Planning drawings and application
- Glazed doors and windows
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 Peterborough
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 Peterborough coverage includes postcode districts PE1, and we also work in nearby places such as Stamford, March and Spalding.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about garden annexes in Peterborough
Do you build garden annexes in Peterborough?
Yes. We build garden annexes across Peterborough, including postcodes PE1. Every project starts with a free home visit.
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.
How much does a garden annexe cost in Peterborough?
In Peterborough, 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.
Can it be accessible?
Yes. Level access, wider doors and a wet room can be designed in.
