Mid Cornwall · PL25
Extensions that reads Trewoon properly
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. Reading Trewoon on the ground is half of the extension job — Trewoon is a commuter village in the PL25 area, with everyday family housing, edge-of-village plots and quick routes to its parent town, with a building stock that leans toward post-war semis and modern estates.
Trewoon sits in Mid Cornwall — covering PL25 from St Austell, Bugle, St Dennis outward.
- Rural / open-countryside policy area
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Measured-survey accuracy from day one
- ✓ One studio — design, planning and build under one roof
- ✓ Local to Mid Cornwall — not a national franchise
Local watch-list
Common Trewoon pitfalls we plan around.
Watch #1
Tighter Local Plan tests on isolated rural dwellings
Who this is for
Trewoon runs the full mix — owner-occupier, holiday-let, commercial and the occasional smallholding — so we scope every extension enquiry from the use-class up.
Local context
Why Trewoon is its own job.
Around Trewoon (PL25), applications here usually turn on neighbour amenity, parking, overlooking and whether new work fits the rhythm of existing streets. For extension specifically, 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. Reading Trewoon properly up front saves more time than any drawing tool ever will. Most of our extension work in Trewoon lands on post-war semis, with detailing that has to nod to the wider Bugle streetscape.
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 Trewoon.
01
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.
02
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.
03
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
04
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
Our process
How a Trewoon 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.
FAQs
Trewoon Extensions — local questions answered.
- 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. In Trewoon specifically, we'd start by checking the latest parish-level planning history before committing to a direction.
- 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.
- Can you handle the build as well as the design?
- Yes — that's the whole point of the studio. One contract, one point of contact, no finger-pointing between architect and builder when something needs a decision on site.
- 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.
- Do I need planning permission for an extension?
- Often no — single-storey rear extensions, side extensions and modest two-storey additions can sit inside permitted development on a typical detached house. Conservation Areas, AONB and Article 4 zones remove some of those rights, so we always check the address first.
Trewoon is part of St Austell
Trewoon sits inside the St Austell catchment — we cover both as one extension territory.
See Extensions in St Austell →Local proof — Most Trewoon homeowners come to us after a extension quote elsewhere felt vague on planning — we lead with feasibility instead.
Get a free feasibility viewOther services in Trewoon
Nearby places we cover
On a Trewoon site the success of a extension is decided in week one — by reading the constraints right, not by drawing them away.