What is a single-storey extension?
A single-storey extension is a ground-floor addition, usually at the rear of a house, that enlarges a kitchen, living or dining space. Most are built with cavity walls on concrete foundations and finished with a flat roof and roof lantern or a pitched tiled roof.
How much does a single-storey extension cost in Brecon?
In Brecon, a single-storey extension typically costs £1,800–£2,650 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £36,000–£53,000. Prices across Wales are typically 8% below the UK average for this kind of work, which is reflected in the range for Brecon. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £25,000–£37,000 |
| Typical project (20 m²) | £36,000–£53,000 |
| Larger project (28 m²) | £50,500–£74,000 |
| Rate per m² | £1,800–£2,650 |
The biggest cost drivers are:
- Roof type and the size of any lantern or roof windows
- Floor area and the length of new wall
- How much of the existing house is opened up
- Glazing: sliding and bifold doors cost more than French doors
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 single-storey extension in Brecon?
Whether you need planning permission depends on your house and its location in Wales. In Wales a single-storey rear extension is often permitted development: up to 4 metres beyond the rear wall and up to 4 metres high, with eaves no higher than 3 metres within 2 metres of a boundary and no more than half the land around the original house covered. Wales has no larger home extension prior approval route, so deeper extensions need a planning application, as do extensions to flats, listed buildings and houses whose rights have been removed.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
Handled as part of most single-storey extensions:
- First and second fix electrics, heating and plastering
- Foundations, drainage and any build-over agreement
- Doors, windows and roof glazing installed
- Knock-through to the existing house with steel beams
- Cavity walls, insulation and roof to current building regulations
- Measured survey and design drawings
How long does it take?
The build itself usually takes 10 to 14 weeks on site for a typical rear extension, after approvals. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Brecon
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Projects in Brecon (LD3) are surveyed in person before we quote, so the price reflects your actual property.
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
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about single-storey extensions in Brecon
How long does a single-storey extension take?
Once approvals are in place, a typical rear extension takes 10 to 14 weeks on site. Design and approvals usually take another 6 to 12 weeks beforehand, depending on whether a planning application is needed.
How much does a single-storey extension cost in Brecon?
In Brecon, a single-storey extension typically costs £1,800–£2,650 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £36,000–£53,000. Your fixed price depends on the survey and drawings.
Do I need planning permission for a single-storey extension in Brecon?
In Wales a single-storey rear extension is often permitted development: up to 4 metres beyond the rear wall and up to 4 metres high, with eaves no higher than 3 metres within 2 metres of a boundary and no more than half the land around the original house covered. Wales has no larger home extension prior approval route, so deeper extensions need a planning application, as do extensions to flats, listed buildings and houses whose rights have been removed.
What is a build-over agreement?
If a public sewer runs within 3 metres of the extension, the water company normally has to agree to the work before it starts. We check sewer records during design and apply where needed.
Can I stay in the house during the build?
Usually yes. We build the shell before opening up the back wall, so the house stays weathertight for most of the job. There will be a few weeks when the kitchen or back room is out of use.
Do you build single-storey extensions in Brecon?
Yes. We build single-storey extensions across Brecon, including postcodes LD3. Every project starts with a free home visit.