South Cornwall · PL25 · Cornwall Council Central
One studio for extension in Charlestown
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. Charlestown sits in South Cornwall, and that geography ends up in the drawings — Charlestown is a Georgian-planned harbour village south of St Austell, World Heritage designated for its china clay shipping history, with tall ships still moored in the harbour, with a building stock that leans toward modern carefully matched coastal homes and Georgian harbour cottages.
Charlestown sits in South Cornwall — just off the A39; covering PL25 from St Austell, Carlyon Bay outward.
- Conservation Area
- Cornish Mining World Heritage Site
- Coastal exposure zone
- ✓One studio — design, planning and build under one roof
- ✓Local to South Cornwall — not a national franchise
- ✓Fixed-fee planning packages, no surprise invoices
- ✓Measured-survey accuracy from day one
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Free Charlestown feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Page purpose
Drawings only, or drawings through to handover in Charlestown?
Both routes are open on a PL25 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Charlestown 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 PL25 scope, not as one opaque figure
Scope
Scope options for Charlestown clients
Clients in Charlestown take different slices of this list, and that is deliberate.
Full design and build
One contract from first sketch to handover, with the same team on paper and on site.
Construction and technical drawings
1:10 and 1:20 details for the parts of the job builders normally have to guess at.
Building regulation drawings
Full Plans sets with sections, construction notes and coordinated structural information.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Local watch-list
Charlestown-specific issues we screen on the first visit.
Watch #1
Conservation Area controls on materials, window proportions and roof form through central Charlestown
Watch #2
World Heritage Site heritage assessment where changes are visible in the mining landscape
Watch #3
Exposure detailing on Georgian harbour cottages — fixings, render systems and joinery specified for salt-laden air
Watch #4
Party Wall notices and shallow roof voids typical of Georgian harbour cottages in the PL25 district
Who this is for
Straight facts about working with us here
- Applications for Charlestown are handled through Cornwall Council, with Truro the nearest planning office we deal with regularly.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
- Drawings, planning and building regulations are all produced in-house, so an extension enquiry does not get passed between firms.
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.
What we focus on
Extensions considerations specific to Charlestown.
01
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
02
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.
03
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.
04
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
Quick check
Want a straight answer on whether your Charlestown 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 Charlestown and the PL25 area.
Local context
Why Charlestown is its own job.
Two things shape a Charlestown application: parish character and policy. On policy — conservation Area covers the entire historic harbour; World Heritage Site status applies. The Charlestown Estate operates a strong design code on materials and layout. For extension specifically, parts of Charlestown sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; the wider area forms part of the Cornish Mining World Heritage Site, which adds a heritage assessment layer to most material changes; coastal salt-laden air around Charlestown drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure. Get that local reading right and the rest of the Charlestown programme tends to run on time. On modern carefully matched coastal homes in particular — the kind you'll also find toward St Austell — the extension brief always has to read the existing fabric first. Historic fabric changes the sequence: survey first, then design around what the building can take. Consent routes for listed buildings sit separately from ordinary planning, so treat any general guidance here as a starting point and check with Cornwall Council. Coastal sites tend to raise questions about roof form, glazing exposure and how a scheme reads from public viewpoints. Those are policy judgements rather than fixed rules, so the local planning authority or the Planning Portal should confirm the position for a given plot.
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.
Our process
How a Charlestown 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
Charlestown Extensions — local questions answered.
- How much does an extension cost in Charlestown?
- 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. In Charlestown specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
- 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.
- 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.
- We live in the house. Can an extension in Charlestown 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 Charlestown are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
Charlestown is part of St Austell
Charlestown sits inside the St Austell catchment — we cover both as one extension territory.
See Extensions in St Austell →Keep reading
Where to go next from Charlestown
Charlestown is covered from our St Austell run. Being a smaller place, the local detail matters more than the headline policy: lane access, neighbour proximity and what the immediate street already looks like.
Other services in Charlestown
Nearby places we cover
In short: take the drawings and run your own build in Charlestown, or keep it under one contract. Both routes start the same way. Parish-level consultation in St Austell is worth planning for, not reacting to.
Drawings only, or the full Charlestown build? Bring the deeds, we will bring the survey kit for the extension.
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