South Cornwall · PL26 · Cornwall Council Mid
House extension costs in Pentewan — what PL26 homeowners actually pay
Most Pentewan cost questions land in the same bracket: a single-storey rear sits roughly £2,200–£2,800/m² built, a two-storey side runs £2,000–£2,500/m², and anything touching a coastal elevation tends to add 8–12% for materials and detailing. We quote on measured drawings, not guesses. Extensions are the bread and butter of Cornish homes — adding the kitchen-diner the original layout never had, the bedroom for a growing family, or the light and views the back of the house should always have had. Anchor any Pentewan extension in the local fabric and the rest follows — Pentewan is an AONB former china clay shipping village south of St Austell, with a tight planned Conservation Area around the silted-up harbour and the holiday park inland, with a building stock that leans toward modern AONB-sensitive infill and Edwardian houses.
Pentewan sits in South Cornwall — just off the B3273; with Truro the closest city; 0 miles from Pentewan, 5 miles from St Austell.
- Conservation Area
- Cornwall AONB
- Coastal exposure zone
- Rural / open-countryside policy area
- ✓ Typical Pentewan single-storey rear: £55k–£85k build cost
- ✓ Two-storey side extension: £85k–£140k build cost
- ✓ Wrap-around / L-shaped: £110k–£180k build cost
- ✓ Design + planning + building regs fee from £4,800 (fixed)
Local proof — We typically have one or two extension jobs live in the PL26 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewLocal context
Why Pentewan is its own job.
Locally, conservation Area covers the harbour village; AONB across the parish. Former harbour silting and Pentewan Sands holiday park shape most local planning conversations. For extension specifically, parts of Pentewan sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; the surrounding landscape falls inside the Cornwall Area of Outstanding Natural Beauty, so massing, height and landscape impact carry extra weight in any planning decision; coastal salt-laden air around Pentewan drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure; Cornwall Council's Local Plan applies tighter tests to isolated rural dwellings here, so design rationale and policy fit need to be set out clearly from the outset. Which is why we scope Pentewan projects parish-up, not template-down — the PL26 context shapes the design from day one. Whether the project is on modern AONB-sensitive infill in the centre or further out toward Gorran Haven, the extension response is locally tuned.
Planning note
Most extensions in Cornwall are either permitted development or a straightforward householder application — but Conservation Area and AONB sites need a more careful design conversation upfront.
What we focus on
Extensions considerations specific to Pentewan.
01
Extensions over a certain proportion of the original house trigger full Part L upgrade obligations to the existing building — worth knowing before brief is set.
02
Permitted development for rear extensions runs to four metres on a detached house, three on a semi or terrace — but Article 4 areas remove this in some parishes.
03
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
04
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
Our process
How a Pentewan extension project runs.
Step 1
Brief
We meet on site, talk through how you live now and what's missing from the current layout.
Step 2
Design
Two or three sketch directions with rough budgets, then refinement of the chosen route.
Step 3
Approvals
Planning or Cert of Lawfulness, then a full building regs package.
Step 4
Build
Either through your own builder with our drawings, or as a full build by our team.
Step 5
Handover
Snag, certify, hand over the keys to your new space.
Typical single-storey rear extensions run twelve to twenty weeks on site; two-storey and wraparound projects sixteen to thirty weeks.
Local fabric
Why Pentewan homeowners pick a local studio for extension.
Building stock
Across Pentewan (PL26) we work on planned harbour cottages, Victorian villas, Edwardian houses, modern AONB-sensitive infill, holiday park static caravans. Each stock type drives a different extension response — modern AONB-sensitive infill in particular needs careful detailing here.
Parish & policy
Pentewan sits in the parish of St Austell Bay, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover PL26 from our studio, with regular extension jobs also running in Pentewan, St Austell, Gorran Haven. Most Pentewan site visits get booked within the same week.
What does a first Pentewan consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a PL26 plot and follow up with a written feasibility note inside a week — no obligation either way.
Request a free visitRecent work nearby
Inner-harbour cottage we worked on retained the slate-hung gable and reorganised behind.
See more recent South Cornwall work →FAQs
Pentewan Extensions — local questions answered.
- What's the average cost of a single-storey extension in Pentewan?
- For a typical 20–30m² rear extension in Pentewan (PL26) we'd expect £55k–£85k including VAT, depending on glazing spec and whether the kitchen is being reworked. Coastal exposure here pushes weather-tightness specs up, which is real money.
- Do extension costs in Pentewan include planning and building regs?
- Our fixed-fee design package covers measured survey, planning drawings, building regs and a tendered cost plan. Build cost is separate and quoted from drawings — never guessed from a phone call.
- What pushes a Pentewan extension over budget?
- Three things: ground conditions you didn't survey for, a planning condition that drives a material change, and "while we're at it" scope creep. We screen all three at feasibility stage so the number you start with is the number you finish on.
- Will my house be liveable during the build?
- For most rear and side extensions, yes — we sequence the works so the kitchen and one bathroom stay functional until the new build is watertight and connected. In Pentewan specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- What about the Party Wall Act?
- If you share a wall with a neighbour or build close to a boundary, the Act applies. We flag it early, recommend a surveyor and keep the programme aligned with the notice period.
- How much does an extension cost in Cornwall?
- Build costs in Cornwall typically run from around £2,200 to £3,200 per square metre for a good-quality single-storey extension, more for kitchen-grade fit-out or complex glazing. We give a realistic budget before drawings start, not after.
Pentewan is the hub for these neighbourhoods
We run extensions across Pentewan and the surrounding PL26 neighbourhoods — same studio, same site team.
- Pentewan
PL26
Other services in Pentewan
Nearby places we cover
Local neighbourhoods in Pentewan
If you're scoping an extension in Pentewan, the honest number depends on three things: ground conditions, finish level and how much of the existing fabric stays. We'll tell you which bracket you're in before you commit to a fee.
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