West Cornwall · TR13
Extensions for Trewennack (TR13)
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. The way we approach extension in Trewennack starts with a measured walk-round — Trewennack is a small rural hamlet in the TR13 area, with scattered homes, lanes and a deliberately quiet settlement pattern, with a building stock that leans toward converted barns and small infill homes.
Trewennack sits in West Cornwall — covering TR13 from Helston, Breage, Ashton outward.
- Rural / open-countryside policy area
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Measured-survey accuracy from day one
- ✓ Same team on paper as on site
- ✓ Plain-English feasibility before any drawings
Our process
How a Trewennack 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 proof — We typically have one or two extension jobs live in the TR13 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewWhat we focus on
Extensions considerations specific to Trewennack.
01
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
02
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
03
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.
04
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.
Local context
Why Trewennack is its own job.
In Trewennack the planning picture is specific: the main planning test is usually whether the proposal remains subordinate, locally detailed and acceptable on access, drainage and neighbour amenity. 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. That local reading is what makes a Trewennack (TR13) project different from a generic Cornwall scheme — and is the whole reason we work this way. On converted barns in particular — the kind you'll also find toward Sithney — the extension brief always has to read the existing fabric first.
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.
Local watch-list
The TR13 constraints that shape a extension brief.
Watch #1
Tighter Local Plan tests on isolated rural dwellings
Trewennack is part of Helston
Trewennack sits inside the Helston catchment — we cover both as one extension territory.
See Extensions in Helston →Local fabric
One TR13 studio, one extension job — start to finish.
Building stock
Across Trewennack (TR13) we work on cottages, farmhouses, converted barns, bungalows, small infill homes. Each stock type drives a different extension response — converted barns in particular needs careful detailing here.
Parish & policy
Trewennack sits in the parish of Trewennack, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR13 from our studio, with regular extension jobs also running in Helston, Breage, Ashton. Most Trewennack site visits get booked within the same week.
Can you handle both planning and build in Trewennack?
Yes — design, planning, building regs and full construction run under one roof. For clients with an existing Trewennack builder we can stop at a tender-ready Full Plans pack instead.
Request a free visitWho this is for
Trewennack runs the full mix — owner-occupier, holiday-let, commercial and the occasional smallholding — so we scope every extension enquiry from the use-class up.
FAQs
Trewennack Extensions — local questions answered.
- 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. In Trewennack specifically, we'd start by checking the latest parish-level planning history 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.
- 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.
- 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.
Other services in Trewennack
Nearby places we cover
The TR13 stretch of West Cornwall has its own rhythm; our extension work respects it, and Cornwall Council usually responds in kind.