England
Rear extensions in Cornwall
We design and build rear extensions across Cornwall, from Redruth and Falmouth to St Austell, covering single-storey kitchen extensions, two-storey additions, side returns and wraparounds.
What are homes in Cornwall like to extend?
Cornwall has Victorian terraces nearer the centre and post-war semis on the edges. Sloping gardens are frequent, which affects floor levels and steps down to the patio.
Rear extension prices in Cornwall
South West prices run slightly above our West Midlands baseline; natural stone to match the house is the main variable. Per square metre including VAT, standard specification:
| Extension | Per m² |
|---|---|
| Single-storey rear extension | £1,980–£3,220 |
| Two-storey (per m² across both floors) | £1,870–£2,810 |
| Side return | £2,390–£3,950 |
| Wraparound | £2,290–£3,740 |
| Glass-led | £2,910–£4,990 |
Planning and building rules in Cornwall
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part 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.
Because rear extensions often sit on or near the boundary, the Party Wall etc. Act 1996 usually applies in England. Notices go out one or two months before work depending on the type of work, and a surveyor's award is only needed if a neighbour does not consent.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent.
Rear extensions we build in Cornwall
- Rear extensions for bungalows
- 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)
- Rear extension plans and planning applications
- Building Regulations for rear extensions
- 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 detached houses
Towns and districts in Cornwall
The main places we cover in Cornwall include Redruth, Falmouth and St Austell, across postcode areas PL and TR.
| Town | Postcode districts | Nearest town we also cover |
|---|---|---|
| Redruth | TR15, TR16 | Camborne (3.5 miles) |
| Falmouth | TR11 | Truro (7.7 miles) |
| St Austell | PL25 | Bodmin (9.2 miles) |
| Truro | TR1 | Falmouth (7.7 miles) |
| Camborne | TR14 | Redruth (3.5 miles) |
| Newquay | TR7 | Truro (10.4 miles) |
| Penzance | TR18 | Helston (11.9 miles) |
| Bodmin | PL31 | St Austell (9.2 miles) |
| Saltash | PL12 | Plymouth (4.5 miles) |
| Helston | TR13 | Camborne (7.7 miles) |
Areas near Cornwall
FAQ
Questions people ask
How much does a rear extension cost in Cornwall?
As a guide, £1,980–£3,220 per square metre including VAT for a standard single-storey extension at South West England rates.
Do I need planning permission in Cornwall?
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.
Which towns in Cornwall do you cover?
10 towns and districts, including Redruth, Falmouth and St Austell.
Do you handle building control?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.