North Cornwall · TR5
Extensions for Trevellas (TR5)
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. Trevellas sits in North Cornwall, and that geography ends up in the drawings — Trevellas is a coastal village in the TR5 area, where sea exposure, views and seasonal pressure shape most building decisions, with a building stock that leans toward bungalows and granite cottages.
Trevellas sits in North Cornwall — covering TR5 from St Agnes, Mount Hawke, Mithian outward.
- Cornwall AONB
- Cornish Mining World Heritage Site
- Coastal exposure zone
- ✓ Same team on paper as on site
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Local to North Cornwall — not a national franchise
- ✓ One studio — design, planning and build under one roof
Our process
How a Trevellas 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 — Most Trevellas extension clients we work with are second-time builders — they've seen the templated approach fail once already.
Get a free feasibility viewWhat we focus on
Extensions considerations specific to Trevellas.
01
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
02
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
03
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
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.
Local context
Why Trevellas is its own job.
In Trevellas the planning picture is specific: coastal setting and landscape sensitivity mean rooflines, glazing, drainage and external materials need careful handling from the first sketch. For extension specifically, 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; the wider area forms part of the Cornish Mining World Heritage Site, which adds a heritage assessment layer to most material changes; coastal salt-laden air around Trevellas drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure. That local reading is what makes a Trevellas (TR5) project different from a generic Cornwall scheme — and is the whole reason we work this way. On bungalows in particular — the kind you'll also find toward Goonbell — 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 TR5 constraints that shape a extension brief.
Watch #1
AONB landscape-impact scrutiny on visible elevations
Watch #2
World Heritage Site assessment on changes visible in the mining landscape
Watch #3
Coastal exposure driving fixing, render and joinery spec
Trevellas is part of St Agnes
Trevellas sits inside the St Agnes catchment — we cover both as one extension territory.
See Extensions in St Agnes →Local fabric
What sets a Trevellas extension brief apart.
Building stock
Across Trevellas (TR5) we work on granite cottages, rendered coastal houses, holiday homes, bungalows, replacement dwellings. Each stock type drives a different extension response — bungalows in particular needs careful detailing here.
Parish & policy
Trevellas sits in the parish of Trevellas, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR5 from our studio, with regular extension jobs also running in St Agnes, Mount Hawke, Mithian. Most Trevellas site visits get booked within the same week.
Can you handle both planning and build in Trevellas?
Yes — design, planning, building regs and full construction run under one roof. For clients with an existing Trevellas builder we can stop at a tender-ready Full Plans pack instead.
Request a free visitWho this is for
Trevellas 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
Trevellas 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 Trevellas specifically, we'd start by checking AONB landscape sensitivity 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.
- 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.
- 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.
Other services in Trevellas
Nearby places we cover
Every Trevellas extension we work on is treated as a TR5 job in its own right — local fabric, local policy, local builders.