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)
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Page purpose
Drawings only, or drawings through to handover in Launceston?
Both routes are open on a PL15 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Launceston 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 PL15 scope, not as one opaque figure
Scope
Scope options for Launceston clients
These stages can be bought separately. Most PL15 projects use three of them.
Building regulation drawings
Full Plans sets with sections, construction notes and coordinated structural information.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Planning application drawings
Existing and proposed plans, elevations, site and block plans drawn to validation standard.
Commercial drawings
Change of use, fit-out and access documentation for Class E and mixed-use premises.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
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
Straight facts about working with us here
- Design and build are offered from the same studio, which means the person answering your Launceston questions has seen the detail built.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
- Sites we know on the ground here include the area around Launceston Castle and Southgate Arch.
- 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 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.
Quick check
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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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For projects in Launceston and the PL15 area.
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. 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.
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.
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.
Keep reading
Where to go next from Launceston
We cover Launceston and the wider PL15 district directly. Extensions enquiries here are common enough that we know the constraints before the first visit.
Other services in Launceston
Nearby places we cover
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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