East Cornwall · PL15 · Cornwall Council East
House extension costs in Launceston — what PL15 homeowners actually pay
Most Launceston cost questions land in the same bracket: a single-storey rear sits roughly £2,200–£2,800/m² built, a two-storey side runs £2,000–£2,500/m², and anything touching a stone-fronted elevation tends to add 8–12% for materials and detailing. We quote on measured drawings, not guesses. 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. The way we approach extension in Launceston starts with a measured walk-round — Launceston is the ancient capital of Cornwall, just over the Tamar from Devon, with the Norman castle, walled medieval core and a substantial Conservation Area covering the historic streets, with a building stock that leans toward Edwardian villas and modern Bovis and Persimmon estates.
Launceston sits in East Cornwall — just off the A30; with Exeter the closest city; covering PL15 from Egloskerry, Lewannick outward.
- Conservation Area
- ✓ Typical Launceston single-storey rear: £55k–£85k build cost
- ✓ Two-storey side extension: £85k–£140k build cost
- ✓ Wrap-around / L-shaped: £110k–£180k build cost
- ✓ Design + planning + building regs fee from £4,800 (fixed)
Local watch-list
What usually catches extension projects out in Launceston.
Watch #1
Town walls and castle setting scrutiny on central plots
Watch #2
Steep medieval street grain restricting access
Watch #3
Conservation Area boundary cutting across mixed-age stock
Watch #4
Tamar Valley AONB at the east edge
Who this is for
In Launceston the extension brief is almost always a private homeowner improving a forever home — so we lead with feasibility and long-term value, not show-home rhetoric.
Local context
Why Launceston is its own job.
In Launceston the planning picture is specific: conservation Area is extensive, covering the medieval walled town, the castle approach and the southern Conservation Area at Newport. Listed buildings are common; significant edge-of-town development pressure on the A30. For extension specifically, parts of Launceston sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape. That local reading is what makes a Launceston (PL15) project different from a generic Cornwall scheme — and is the whole reason we work this way. On Edwardian villas in particular — the kind you'll also find toward North Petherwin — the extension brief always has to read the existing fabric first.
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 Launceston.
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.
Recent work nearby
Recent Southgate-adjacent shop-to-flat we delivered kept the Georgian shopfront and inserted a contemporary rear pod.
See more recent East Cornwall work →Our process
How a Launceston 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
Launceston Extensions — local questions answered.
- What's the average cost of a single-storey extension in Launceston?
- For a typical 20–30m² rear extension in Launceston (PL15) we'd expect £55k–£85k including VAT, depending on glazing spec and whether the kitchen is being reworked. Coastal exposure here pushes weather-tightness specs up, which is real money.
- Do extension costs in Launceston include planning and building regs?
- Our fixed-fee design package covers measured survey, planning drawings, building regs and a tendered cost plan. Build cost is separate and quoted from drawings — never guessed from a phone call.
- What pushes a Launceston extension over budget?
- Three things: ground conditions you didn't survey for, a planning condition that drives a material change, and "while we're at it" scope creep. We screen all three at feasibility stage so the number you start with is the number you finish on.
- 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. In Launceston specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
Launceston is the hub for these neighbourhoods
We run extensions across Launceston and the surrounding PL15 neighbourhoods — same studio, same site team.
- Warbstow
PL15
- North Petherwin
PL15
- Boyton
PL15
- South Petherwin
PL15
- Egloskerry
PL15
- Lewannick
PL15
- Altarnun
PL15
- Polyphant
PL15
- Tregadillett
PL15
Local proof — Most Launceston extension clients we work with are second-time builders — they've seen the templated approach fail once already.
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Nearby places we cover
Local neighbourhoods in Launceston
If you're scoping an extension in Launceston, the honest number depends on three things: ground conditions, finish level and how much of the existing fabric stays. We'll tell you which bracket you're in before you commit to a fee.
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