How much does a granny annexe cost in the UK?
A granny annexe costs £60,000 on average in the UK. Most jobs fall between £30,000 and £150,000 installed. Annexe type: Garden annexe £30,000 to £60,000; Larger or brick-built annexe £60,000 to £100,000; Attached extension annexe £80,000 to £150,000. Prices reviewed June 2026.
A granny annexe, also called a granny flat, is a self-contained living space with its own kitchen and bathroom, in the garden or attached to the house. Cost depends on size, build type and the fit-out.
Granny annexe cost calculator
Use the calculator to price your granny annexe in 2026. Adjust the options and area for a UK cost range. Nothing is sent anywhere.
Granny annexe cost breakdown
Typical granny annexe costs, by option:
| Annexe type | Typical UK cost |
|---|---|
| Garden annexe (modular, one bed) | £30,000 to £60,000 |
| Larger or brick-built annexe | £60,000 to £100,000 |
| Attached extension annexe | £80,000 to £150,000 |
| + Full kitchen and bathroom fit-out | add £8,000 to £20,000 |
| + Utilities connected to the main house | add £3,000 to £10,000 |
What's included in the price?
Typical granny annexe prices include:
- The structure, insulated for year-round living
- Kitchen and bathroom fit-out
- Electrics, heating and plumbing
- Connection to services
What changes the price?
The things that move granny annexe prices most:
Garden annexe versus an attached extension
Size and number of rooms
Kitchen and bathroom spec
Connecting utilities to the main house
Does where you live change the cost?
In London, a granny annexe typically costs around £78,000 installed, about 30% above the UK average of £60,000. In the North, Scotland and Wales the guide figure is nearer £55,000.
| Region | From | Typical | Up to |
|---|---|---|---|
| Midlands / East (UK average) | £30,000 | £60,000 | £150,000 |
| London | £39,000 | £78,000 | £195,000 |
| South East / South West | £34,500 | £69,000 | £172,500 |
| North / Scotland / Wales | £27,500 | £55,000 | £138,000 |
Guide prices installed, scaled with the same regional multipliers as the calculator. Not quotes.
Granny annexe cost in major UK cities
| City | From | Typical | Up to |
|---|---|---|---|
| Belfast | £25,500 | £51,000 | £127,500 |
| Birmingham | £29,500 | £59,000 | £147,000 |
| Bristol | £33,000 | £66,000 | £165,000 |
| Cardiff | £28,000 | £56,500 | £141,000 |
| Edinburgh | £29,500 | £59,000 | £147,000 |
| Glasgow | £27,000 | £54,000 | £135,000 |
| Leeds | £28,000 | £56,000 | £139,500 |
| Liverpool | £27,500 | £55,000 | £138,000 |
| London | £39,000 | £78,000 | £195,000 |
| Manchester | £29,000 | £57,500 | £144,000 |
| Newcastle | £27,000 | £54,000 | £135,000 |
| Sheffield | £27,500 | £55,000 | £138,000 |
City guide estimates, scaled by local labour costs. Indicative averages for granny annexe, not quotes.
In London and the South East, figures run above the national figures, mainly on labour and groundwork.
Common questions
How much does a granny annexe cost?
A granny annexe costs roughly £30,000 to £150,000 installed in the UK, typically around £60,000. A modular one-bed garden annexe is £30,000 to £60,000, a larger or brick-built annexe £60,000 to £100,000, and an attached extension annexe £80,000 to £150,000. A full kitchen and bathroom fit-out and connecting utilities to the main house add to that.
Do I need planning permission for a granny annexe?
It depends on how it is used. A garden building used as an extra room can fall under permitted development, but a fully self-contained annexe with its own kitchen, bathroom and entrance, lived in independently, usually needs planning permission, because it counts as a separate dwelling. Always check with your council before building, as getting it wrong can mean an enforcement notice.
Do you pay council tax on a granny annexe?
Often, yes. A self-contained annexe can be banded separately for council tax, though there is a 50 percent discount where it is occupied by a dependent relative or used as part of the main home, and a full exemption in some cases such as an elderly or disabled relative living there. It is worth checking your council's rules, because the treatment varies by situation.
Is a granny annexe a good idea?
For keeping family close while giving everyone independence, an annexe can be well worth the £30,000 to £150,000, and it can add value or rental potential later. The things to weigh are the planning position, the council tax treatment, and whether the layout genuinely gives privacy for both households. Get the planning and council tax questions answered before committing, because they shape the whole project.
Is a granny annexe cheaper than an extension?
A modular garden annexe can undercut a full attached extension for the same floor space, because it is built off-site and needs less groundwork, while an attached or two-storey annexe costs as much as or more than an extension. It also keeps the accommodation separate, which is the point of an annexe. So it depends on whether you want separate, independent space or simply more room joined to the house.
Can I build a granny annexe myself?
If you are a capable builder you can self-build and save on labour, but most people buy a modular garden annexe, from £30,000 to £60,000, because it arrives largely finished. Foundations, drainage and connecting utilities to the main house, around £3,000 to £10,000, plus the kitchen and bathroom fit-out at £8,000 to £20,000, are where the skill and cost sit. Building regulations apply if someone will sleep there, so budget for sign-off.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.