Cardiff and the Vale
Rear extensions in Cardiff
From the first measured visit to building control sign-off, we handle rear extensions in Cardiff under one contract.
Cardiff is in Cardiff and the Vale, with postcode districts including CF3, CF5, CF11, CF14 and CF23. The nearest places we also cover are Whitchurch (2.8 miles) and Penarth (2.9 miles).
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
Rear extensions we build in Cardiff
- Single-storey rear extensions
- Two-storey rear extensions
- Kitchen-diner rear extensions
- Side return extensions
- Wraparound extensions
- Glazed and glass-box rear extensions
- Rear extensions for terraced houses
- Rear extensions for semi-detached houses
- Rear extensions for bungalows
- Rear extension plans and planning applications
Also available across Cardiff and the Vale:
- Rear extensions for detached houses
- Flat-roof rear extensions
- Pitched and lean-to roof rear extensions
- Knocking through to a rear extension
- Roof lanterns and rooflights for rear extensions
- Permitted development rear extensions
- Building Regulations for rear extensions
Rear extension prices in Cardiff
Prices in Wales sit below our West Midlands baseline; sloping sites are the main variable.
| Example | Guide inc VAT |
|---|---|
| Single-storey, 3 m × 4 m (12 m²) | £21,000–£34,500 |
| Single-storey, 4 m × 6 m (24 m²) | £42,500–£69,000 |
| Two-storey, 3 m × 5 m footprint (30 m²) | £50,000–£75,500 |
| Side return, about 14 m² | £30,000–£49,500 |
| Wraparound, about 25 m² | £51,000–£83,500 |
What are homes in Cardiff like to extend?
Older terraces near the centre and post-war semis further out are typical of Cardiff. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start.
Planning rules for Cardiff
The Welsh Government's householder rules let many homes add a single-storey rear extension up to 4 metres deep and 4 metres high without a planning application. Deeper projects go through a householder application, because Wales has no prior approval route.
Welsh building regulations apply to every rear extension. The council or a registered approver checks the work against the Welsh Approved Documents and issues a completion certificate.
Nearby towns
FAQ
Questions people ask
How much is a rear extension in Cardiff?
A 3 m × 4 m single-storey rear extension is about £21,000–£34,500 including VAT at our Wales guide rates; the written price follows a survey.
Do I need planning permission in Cardiff?
Often not for a single-storey rear extension of up to 4 metres under Welsh permitted development. Wales has no prior approval route for deeper extensions.
Is the site visit in Cardiff free?
Yes, with no obligation.
Do I need a party wall agreement?
In Wales, usually yes if the extension is on or near a shared boundary or close to a neighbour's foundations. We serve the notices.