St Austell, Cornwall
Two-storey rear extension in St Austell
A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We design, get the approvals for and build two-storey rear extensions in St Austell and the surrounding area, with one contract from the first survey to building control sign-off.
St Austell sits in Cornwall, with postcode districts including PL25. In St Austell, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a two-storey rear extension cost in St Austell?
In St Austell, our guide for a two-storey rear extension is £1,870–£2,810 per square metre including VAT for a standard specification. South West prices run slightly above our West Midlands baseline; natural stone to match the house is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £56,000–£84,000 |
| 4 m × 6 m footprint, two floors (48 m²) | £90,000–£135,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a two-storey rear extension in St Austell?
The planning route for a two-storey rear extension in St Austell is set by England's householder rules and your council.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in St Austell like to extend?
Stone-built and rendered houses are common around St Austell, so matching the walling is a design decision in its own right: natural stone, reconstituted stone or a render finish across old and new.
How a two-storey rear extension in St Austell comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Two-storey rear extensions near St Austell
We also build two-storey rear extensions in nearby Bodmin (9.2 miles) and Truro (13.5 miles).
- Two-storey rear extension in Bodmin
- Two-storey rear extension in Truro
- Two-storey rear extension in Newquay
- Two-storey rear extension in Falmouth
- Two-storey rear extension in Redruth
Other work in St Austell:
FAQ
Two-storey rear extension questions in St Austell
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Is the site visit in St Austell free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
What is the 45-degree rule?
Many councils check that a two-storey extension does not cross a 45-degree line drawn from the nearest habitable window of the neighbouring house. We test it at the first drawing.
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.
Do you handle building control in St Austell?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
How long does a rear extension take to build in St Austell?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.