Penwith · TR19 · Cornwall Council West
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 — just off the A30; 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 West sub-area regulars
- ✓30+ years of Cornwall Council approvals
- ✓Measured-survey accuracy from day one
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Free Sennen feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
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.
Scope
What we can draw, survey and build around Sennen
These stages can be bought separately. Most TR19 projects use three of them.
Planning application drawings
Existing and proposed plans, elevations, site and block plans drawn to validation standard.
Full design and build
One contract from first sketch to handover, with the same team on paper and on site.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
Construction and technical drawings
1:10 and 1:20 details for the parts of the job builders normally have to guess at.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Page purpose
Drawings only, or drawings through to handover in Sennen?
Both routes are open on a TR19 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Sennen 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 TR19 scope, not as one opaque figure
Keep reading
Follow the chain: survey, drawings, build
Sennen works as a hub for us: the same extension team covers Porthcurno, Escalls and the surrounding TR19 villages, so a site visit here often takes in more than one address.
Who this is for
Why this page exists, and who it is for
- Drawings, planning and building regulations are all produced in-house, so a extension enquiry does not get passed between firms.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
- Applications for Sennen are handled through Cornwall Council, with Truro the nearest planning office we deal with regularly.
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.
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.
Quick check
Want a straight answer on whether your Sennen 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.
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Get a free feasibility view
For projects in Sennen and the TR19 area.
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.
- We live in the house. Can a extension in Sennen 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 Sennen 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.
- 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
- Escalls
TR19
Other services in Sennen
Nearby places we cover
Local neighbourhoods in Sennen
To sum up, our extension approach in Sennen is built entirely around local Cornwall context, ensuring the best possible outcome for your property. Applications are dealt with through Cornwall Council, with Truro the office we deal with most for TR19.
Decide the route after the free Sennen visit Free first visit, TR19 included.
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