Penwith · TR19
Sennen extensions — a Penwith studio
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. Anchor any Sennen extension in the local fabric and the rest follows — Sennen is the most westerly mainland village, on the cliffs above Sennen Cove and the white-sand beach of Whitesand Bay, AONB-designated and entirely within Heritage Coast, with a building stock that leans toward granite cliff cottages and modern AONB-sensitive replacement dwellings.
Sennen sits in Penwith — covering TR19 from St Just in Penwith, Porthcurno outward.
- Conservation Area
- Cornwall AONB
- Coastal exposure zone
- Rural / open-countryside policy area
- ✓ Conservation Area experience built into the fee
- ✓ Cornwall Council regulars across every sub-area
- ✓ 30+ years of Cornwall Council approvals
- ✓ Measured-survey accuracy from day one
Local proof — We typically have one or two extension jobs live in the TR19 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewLocal context
Why Sennen is its own job.
The planning backdrop in Penwith is real, not abstract: conservation Area covers Sennen churchtown and the cove; AONB and Heritage Coast across the parish. Cliff-edge sites face strict controls on materials and ridge heights. For extension specifically, parts of Sennen sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; 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 Sennen drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure; 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. Treat the TR19 parish brief as the design brief and the Sennen application has somewhere to land. Whether the project is on granite cliff cottages in the centre or further out toward Porthcurno, the extension response is locally tuned.
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 Sennen.
01
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
02
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.
03
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
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 Sennen 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 Sennen homeowners pick a local studio for extension.
Building stock
Across Sennen (TR19) we work on granite cliff cottages, Edwardian guesthouses, 1960s coastal bungalows, modern AONB-sensitive replacement dwellings. Each stock type drives a different extension response — granite cliff cottages in particular needs careful detailing here.
Parish & policy
Sennen is its own town in Penwith, with planning history that's specific to the TR19 catchment.
Coverage
We cover TR19 from our studio, with regular extension jobs also running in St Just in Penwith, Porthcurno, St Buryan. Most Sennen site visits get booked within the same week.
What does a first Sennen consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a TR19 plot and follow up with a written feasibility note inside a week — no obligation either way.
Request a free visitFAQs
Sennen 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 Sennen specifically, we'd start by checking the Conservation Area boundary 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.
- 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.
- 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.
Sennen is the hub for these neighbourhoods
We run extensions across Sennen and the surrounding TR19 neighbourhoods — same studio, same site team.
- Porthcurno
TR19
Other services in Sennen
Nearby places we cover
Local neighbourhoods in Sennen
A extension in Sennen stands or falls on how well it reads the street — we treat that as the design brief, not an afterthought.