Cornwall
Rear extensions in Penzance
From the first measured visit to building control sign-off, we handle rear extensions in Penzance under one contract.
Penzance is in Cornwall, with postcode districts including TR18. The nearest places we also cover are Helston (11.9 miles) and Camborne (12.5 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 Penzance
- 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 Cornwall:
- 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
- Larger home extension prior approval (England)
- Building Regulations for rear extensions
Rear extension prices in Penzance
South West prices run slightly above our West Midlands baseline; natural stone to match the house is the main variable.
| Example | Guide inc VAT |
|---|---|
| Single-storey, 3 m × 4 m (12 m²) | £23,500–£38,500 |
| Single-storey, 4 m × 6 m (24 m²) | £47,500–£77,500 |
| Two-storey, 3 m × 5 m footprint (30 m²) | £56,000–£84,000 |
| Side return, about 14 m² | £33,500–£55,500 |
| Wraparound, about 25 m² | £57,000–£93,500 |
What are homes in Penzance like to extend?
Stone-built and rendered houses are common around Penzance, so matching the walling is a design decision in its own right: natural stone, reconstituted stone or a render finish across old and new.
Planning rules for Penzance
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Planning and Building Regulations are separate in England: even a permitted development extension is inspected for foundations, drainage, structure, insulation, fire safety and ventilation, through the council or a registered building control approver, ending with a completion certificate.
Nearby towns
FAQ
Questions people ask
How much is a rear extension in Penzance?
A 3 m × 4 m single-storey rear extension is about £23,500–£38,500 including VAT at our South West England guide rates; the written price follows a survey.
Do I need planning permission in Penzance?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Is the site visit in Penzance free?
Yes, with no obligation.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.