St Austell side return extensions, designed and built
We design and build side return extensions for houses in St Austell, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in St AustellFrom £18,000 inc VAT
- PlanningOften permitted development; party wall notice usual
- Build time10–14 weeks on site
- Postcode districtsPL25
Do I need planning permission in St Austell?
In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
Included in a typical project
- Glazed, sloping or flat roof with rooflights
- Kitchen-ready shell or full finish
- Removal of the side wall and new steelwork
- Party wall notice support (England and Wales)
- Survey of the outrigger, boundary wall and drainage
- New boundary wall or raised party wall
Side return extension prices in St Austell
These guide figures apply our South West England adjustment (×1.02) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in St Austell: £2,140 to £3,880 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £18,000 – £22,000 | £19,500 – £24,500 | £24,000 – £31,500 |
| 2 m × 5.5 m 11 m² | £23,500 – £28,500 | £26,500 – £34,000 | £33,500 – £43,000 |
| 2.2 m × 7 m 15 m² | £32,000 – £38,500 | £36,500 – £46,000 | £45,500 – £58,500 |
For a figure based on your own dimensions, use our guide-price tool.
Local to St Austell
We cover St Austell and the postcode districts PL25. Nearby, we also take on projects in Bodmin (9 miles), Truro (13 miles), Newquay (14 miles), Falmouth (18 miles).
South West homes range from terraced streets in the cities to stone cottages and bungalows in the countryside, and conservation areas are common in historic centres.
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Your questions about a side return extension in St Austell
Do you cover all of St Austell?
Yes. We cover St Austell and the surrounding parts of Cornwall. Site visits are free and there is no obligation.
Will my neighbours in St Austell be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
How long does a side return extension take to build in St Austell?
On site, typically 10 to 14 weeks once approvals are in place. Before that, allow 6–12 weeks design and approvals.
Will the kitchen be darker?
Not if the roof is designed well. A glazed roof or a line of rooflights along the boundary usually makes the room brighter than before.
How much does a side return extension cost?
Our guide range is about £2,140 to £3,880 per m² including VAT, so a typical 2 m × 5.5 m infill lands around £26,500 to £34,000 at standard spec in St Austell, more in London.
Book a free site visit in St Austell
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.