North Cornwall · PL27
House Extensions in Trebetherick
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 Trebetherick version of this work has its own character — Trebetherick is a holiday-coast settlement in the PL27 area, with strong second-home demand and exposed coastal building conditions, with a building stock that leans toward holiday lets and detached houses.
Trebetherick sits in North Cornwall — covering PL27 from Polzeath, Truro, St Austell outward.
- Cornwall AONB
- Coastal exposure zone
- ✓ One studio — design, planning and build under one roof
- ✓ Local to North Cornwall — not a national franchise
- ✓ Same team on paper as on site
- ✓ Fixed-fee planning packages, no surprise invoices
Local watch-list
What usually catches extension projects out in Trebetherick.
Watch #1
AONB landscape-impact scrutiny on visible elevations
Watch #2
Coastal exposure driving fixing, render and joinery spec
Who this is for
Trebetherick 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 Trebetherick is its own job.
Planning scrutiny often focuses on visual impact, occupancy, parking, overlooking and whether replacement buildings respect the coastal edge. 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; coastal salt-laden air around Trebetherick drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure. So every Trebetherick job runs as a PL27-specific piece of work — local policy, local fabric, local builders. Most of our extension work in Trebetherick lands on holiday lets, with detailing that has to nod to the wider Truro 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 Trebetherick.
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
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.
Our process
How a Trebetherick 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
Trebetherick 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 Trebetherick specifically, we'd start by checking AONB landscape sensitivity 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.
- 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.
- 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.
Trebetherick is part of Polzeath
Trebetherick sits inside the Polzeath catchment — we cover both as one extension territory.
See Extensions in Polzeath →Local proof — Recent extension enquiries from Trebetherick have clustered around holiday lets — we know the route through Cornwall Council on these.
Get a free feasibility viewOther services in Trebetherick
Nearby places we cover
If you're considering a extension project in the PL27 area, our deep understanding of Trebetherick's architectural character can help navigate the process smoothly.