Lizard Peninsula · TR12
Design, planning and build for Goonhilly extension
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. What works on a TR12 plot rarely works elsewhere — Goonhilly is a moorland-edge hamlet in the TR12 area, where exposed weather, narrow lanes and rural character set the brief, with a building stock that leans toward stone cottages and small rural infill.
Goonhilly sits in Lizard Peninsula — covering TR12 from St Keverne, Truro, St Austell outward.
- Cornwall AONB
- Rural / open-countryside policy area
- ✓ 30+ years of Cornwall Council approvals
- ✓ AONB experience built into the fee
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Measured-survey accuracy from day one
Local proof — Most Goonhilly homeowners come to us after a extension quote elsewhere felt vague on planning — we lead with feasibility instead.
Get a free feasibility viewLocal context
Why Goonhilly is its own job.
Cornwall Council's lens on Goonhilly is consistent: rural policy, landscape impact and services such as drainage are usually the key constraints, especially outside settlement boundaries. 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; 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's why we treat every Goonhilly project as a TR12-area job first — not a generic Cornwall job with a postcode bolted on. The stone cottages that dominate Goonhilly (and continue out toward St Austell) set the tone for any extension scheme here.
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 Goonhilly.
01
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.
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
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
Our process
How a Goonhilly 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
Why Goonhilly homeowners pick a local studio for extension.
Building stock
Across Goonhilly (TR12) we work on stone cottages, farm buildings, isolated houses, converted barns, small rural infill. Each stock type drives a different extension response — stone cottages in particular needs careful detailing here.
Parish & policy
Goonhilly sits in the parish of Goonhilly, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR12 from our studio, with regular extension jobs also running in St Keverne, Truro, St Austell. Most Goonhilly site visits get booked within the same week.
How quickly can you visit a Goonhilly site?
Usually within the same week. Goonhilly (TR12) is on our regular Lizard Peninsula run, alongside St Keverne, Truro, St Austell. First visits are free and you'll get an honest feasibility view inside seven days.
Request a free visitFAQs
Goonhilly 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 Goonhilly specifically, we'd start by checking AONB landscape sensitivity before committing to a direction.
- 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.
- 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.
Goonhilly is part of St Keverne
Goonhilly sits inside the St Keverne catchment — we cover both as one extension territory.
See Extensions in St Keverne →Other services in Goonhilly
Nearby places we cover
Designing a extension in Goonhilly is as much about reading the parish as reading the brief; we do both, and the planning outcomes follow.