South Cornwall · TR10
Treverva extensions — a South Cornwall studio
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. On a Treverva site, the brief always meets the place — Treverva is a rural parish in the TR10 area, with farmsteads, lanes and scattered homes defining its built character, with a building stock that leans toward farmhouses and converted barns.
Treverva sits in South Cornwall — covering TR10 from Falmouth, Flushing, Budock Water outward.
- Rural / open-countryside policy area
- ✓ Free first site visit, no obligation
- ✓ Plain-English feasibility before any drawings
- ✓ Cornwall Council regulars across every sub-area
- ✓ Local to South Cornwall — not a national franchise
Who this is for
Treverva 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 watch-list
What usually catches extension projects out in Treverva.
Watch #1
Tighter Local Plan tests on isolated rural dwellings
Local proof — Most Treverva extension clients we work with are second-time builders — they've seen the templated approach fail once already.
Get a free feasibility viewFAQs
Treverva Extensions — local questions answered.
- 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. In Treverva specifically, we'd start by checking the latest parish-level planning history before committing to a direction.
- How long does the whole process take?
- Allow roughly three months for design and approvals, then twelve to twenty weeks on site for a typical single-storey extension. Wraparounds and two-storey add-ons take longer, mostly through approval and groundworks.
- 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.
- 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.
Local context
Why Treverva is its own job.
The planning backdrop in South Cornwall is real, not abstract: open-countryside policy, access lanes, drainage and agricultural building history all need to be addressed before drawings go too far. 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. Treat the TR10 parish brief as the design brief and the Treverva application has somewhere to land. Whether the project is on farmhouses in the centre or further out toward Falmouth, 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 Treverva.
01
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
02
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
03
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
04
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.
Our process
How a Treverva 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
Choosing a extension team that actually knows TR10.
Building stock
Across Treverva (TR10) we work on farmhouses, converted barns, rural cottages, smallholdings, scattered modern homes. Each stock type drives a different extension response — farmhouses in particular needs careful detailing here.
Parish & policy
Treverva sits in the parish of Treverva, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR10 from our studio, with regular extension jobs also running in Falmouth, Flushing, Budock Water. Most Treverva site visits get booked within the same week.
What does a first Treverva consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a TR10 plot and follow up with a written feasibility note inside a week — no obligation either way.
Request a free visitTreverva is part of Falmouth
Treverva sits inside the Falmouth catchment — we cover both as one extension territory.
See Extensions in Falmouth →Other services in Treverva
Nearby places we cover
From initial feasibility to final handover, we manage extension projects across Treverva with careful attention to what makes South Cornwall unique.