North Cornwall · TR5 · Cornwall Council North
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 — just off the A39; 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
Free · No obligation
Free Trevellas feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Page purpose
Drawings only, or drawings through to handover in Trevellas?
Both routes are open on a TR5 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Trevellas clients take the drawings, tender them locally, then come back to us for the build if the numbers do not stack up.
- Route one: feasibility, planning and a tender-ready technical pack
- Route two: the same pack, then the build under one contract
- Either way the survey and feasibility work is identical, so the decision can wait
- Fees quoted per stage against the TR5 scope, not as one opaque figure
Scope
Scope options for Trevellas clients
These stages can be bought separately. Most TR5 projects use three of them.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Structural coordination
Calculations coordinated with the drawings so building control sees one consistent story.
Full design and build
One contract from first sketch to handover, with the same team on paper and on site.
Construction and technical drawings
1:10 and 1:20 details for the parts of the job builders normally have to guess at.
Building regulation drawings
Full Plans sets with sections, construction notes and coordinated structural information.
Local watch-list
The TR5 constraints that shape a extension brief.
Watch #1
AONB landscape-impact testing on anything read in long views across North Cornwall
Watch #2
World Heritage Site heritage assessment where changes are visible in the mining landscape
Watch #3
Exposure detailing on granite cottages — fixings, render systems and joinery specified for salt-laden air
Watch #4
Party Wall notices and shallow roof voids typical of granite cottages in the TR5 district
Who this is for
Straight facts about working with us here
- Applications for Trevellas are handled through Cornwall Council, with Bodmin the nearest planning office we deal with regularly.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
- Drawings, planning and building regulations are all produced in-house, so a extension enquiry does not get passed between firms.
Planning rules change and every site is different. For the final position on your address, check with Cornwall Council as the local planning authority or the Planning Portal.
What 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.
Quick check
Want a straight answer on whether your Trevellas project is worth pursuing?
Send a few details — we'll come back within 1 working day with a plain-English view on planning risk, likely cost band and whether it's a project we'd take on.
Free · No obligation
Get a free feasibility view
For projects in Trevellas and the TR5 area.
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.
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.
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.
- We live in the house. Can a extension in Trevellas be done while we stay put?
- Usually yes for single-storey and rear work, with a temporary kitchen or bathroom arrangement agreed before the start. Whole-house remodels and roof work in Trevellas are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
- 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.
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 →Keep reading
Where to go next from Trevellas
Trevellas is covered from our St Agnes run. Being a smaller place, the local detail matters more than the headline policy: lane access, neighbour proximity and what the immediate street already looks like.
Other services in Trevellas
Nearby places we cover
To sum up, our extension approach in Trevellas is built entirely around local Cornwall context, ensuring the best possible outcome for your property. Applications are dealt with through Cornwall Council, with Bodmin the office we deal with most for TR5.
Pencil in a free Trevellas visit this week We are on the A39 regularly.
Free · No obligation
Book a free visit in Trevellas
No obligation. Reply usually same working day.