East Cornwall · PL22 · Cornwall Council East
House extension costs in Lostwithiel — what PL22 homeowners actually pay
Most Lostwithiel 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. Working in Lostwithiel means starting from the PL22 context — Lostwithiel is a medieval town on the river Fowey, formerly the capital of Cornwall, with a strong antiques trade, a Norman church and an extensive Conservation Area, with a building stock that leans toward Victorian terraces and post-war estates.
Lostwithiel sits in East Cornwall — just off the A38; covering PL22 from Fowey, Lerryn outward.
- Conservation Area
- ✓Typical Lostwithiel 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 Lostwithiel?
Both routes are open on a PL22 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Lostwithiel 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 PL22 scope, not as one opaque figure
Scope
Scope options for Lostwithiel clients
These stages can be bought separately. Most PL22 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
The PL22 constraints that shape an extension brief.
Watch #1
Conservation Area controls on materials, window proportions and roof form through central Lostwithiel
Who this is for
Straight facts about working with us here
- Applications for Lostwithiel are handled through Cornwall Council, with Liskeard 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 Lostwithiel.
01
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.
02
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
03
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
04
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
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For projects in Lostwithiel and the PL22 area.
Local context
Why Lostwithiel is its own job.
In Lostwithiel the planning picture is specific: conservation Area is extensive, covering the medieval streets, the church and the riverside. Listed buildings are very common; flood zone designation affects properties near the river. For extension specifically, parts of Lostwithiel 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 Lostwithiel (PL22) project different from a generic Cornwall scheme — and is the whole reason we work this way. On Victorian terraces in particular — the kind you'll also find toward Tywardreath — the extension brief always has to read the existing fabric first. On older stock, the practical constraint is usually joinery, render and roof line rather than the extension itself. We draw those details out early so an extension submission is not sent back for missing information. Confirm listing status with the local planning authority before assuming permitted development.
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 Lostwithiel 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
Lostwithiel Extensions — local questions answered.
- What's the average cost of a single-storey extension in Lostwithiel?
- For a typical 20–30m² rear extension in Lostwithiel (PL22) 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 Lostwithiel 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 Lostwithiel 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 Lostwithiel specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- We live in the house. Can an extension in Lostwithiel 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 Lostwithiel 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.
Keep reading
Where to go next from Lostwithiel
We cover Lostwithiel and the wider PL22 district directly. Extensions enquiries here are common enough that we know the constraints before the first visit.
If you're scoping an extension in Lostwithiel, 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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