West Cornwall · TR13 · Cornwall Council West
Design, planning and build for Helston 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 TR13 plot rarely works elsewhere — Helston is the gateway to the Lizard Peninsula and Cornwall's most westerly market town, famous for the Furry Dance and a steep granite-paved Coinagehall Street, with a building stock that leans toward modern estates at Trannack and post-war semis.
Helston sits in West Cornwall — just off the A394; with Truro the closest city; covering TR13 from Porthleven, Mullion outward.
- Conservation Area
- ✓ Conservation Area experience built into the fee
- ✓ 30+ years of Cornwall Council approvals
- ✓ Same team on paper as on site
- ✓ Fixed-fee planning packages, no surprise invoices
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 viewLocal context
Why Helston is its own job.
Cornwall Council's lens on Helston is consistent: the Conservation Area covers the medieval core and Coinagehall Street; shop frontages, sash windows and listed building stock dominate the design conversation. RNAS Culdrose to the south sets some height and roofline constraints in the southern parishes. For extension specifically, parts of Helston sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape. That's why we treat every Helston project as a TR13-area job first — not a generic Cornwall job with a postcode bolted on. The modern estates at Trannack that dominate Helston (and continue out toward Porthleven) 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 Helston.
01
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
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.
Our process
How a Helston 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 Helston homeowners pick a local studio for extension.
Building stock
Across Helston (TR13) we work on Georgian townhouses, granite-and-slate terraces, Victorian villas, post-war semis, modern estates at Trannack. Each stock type drives a different extension response — modern estates at Trannack in particular needs careful detailing here.
Parish & policy
Helston is its own town in West Cornwall, with planning history that's specific to the TR13 catchment.
Coverage
We cover TR13 from our studio, with regular extension jobs also running in Porthleven, Mullion. Most Helston site visits get booked within the same week.
How quickly can you visit a Helston site?
Usually within the same week. Helston (TR13) is on our regular West Cornwall run, alongside Porthleven, Mullion. First visits are free and you'll get an honest feasibility view inside seven days.
Request a free visitRecent work nearby
Helston farm barn conversion last winter ran as a Class Q with full planning fallback.
See more recent West Cornwall work →FAQs
Helston Extensions — local questions answered.
- 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. In Helston specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
- 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.
- 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.
Other services in Helston
Nearby places we cover
Designing a extension in Helston is as much about reading the parish as reading the brief; we do both, and the planning outcomes follow.