South Cornwall · PL22 · Cornwall Council Central
House Extensions in Lerryn
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 Lerryn version of this work has its own character — Lerryn is a creekside settlement in the PL22 area, with waterside homes, wooded valleys and narrow-lane access shaping the brief, with a building stock that leans toward boat sheds and waterside homes.
Lerryn sits in South Cornwall — just off the A39; covering PL22 from Lostwithiel, St Winnow, Lanlivery outward.
- Conservation Area
- ✓One studio — design, planning and build under one roof
- ✓Local to South Cornwall — not a national franchise
- ✓Same team on paper as on site
- ✓Fixed-fee planning packages, no surprise invoices
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Free Lerryn feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Local watch-list
The PL22 constraints that shape a extension brief.
Watch #1
Conservation Area controls on materials, window proportions and roof form through central Lerryn
Watch #2
Party Wall notices and shallow roof voids typical of creekside cottages in the PL22 district
Who this is for
In Lerryn 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.
Scope
The parts of the job we can take on in Lerryn
Not every project needs every stage. On a Lerryn job we scope to what the site and the consent route actually require.
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.
Structural coordination
Calculations coordinated with the drawings so building control sees one consistent story.
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.
Who this is for
What we can genuinely back up in Lerryn
- Design and build are offered from the same studio, which means the person answering your Lerryn questions has seen the detail built.
- 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.
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.
Keep reading
Other work we do around Lerryn
Lerryn is covered from our Lostwithiel 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.
Page purpose
Drawings only, or drawings through to handover in Lerryn?
Both routes are open on a PL22 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Lerryn 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
Local context
Why Lerryn is its own job.
Creekside ecology, flood risk, trees and views across the water often matter as much as the building form itself. For extension specifically, parts of Lerryn sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape. So every Lerryn job runs as a PL22-specific piece of work — local policy, local fabric, local builders. Most of our extension work in Lerryn lands on boat sheds, with detailing that has to nod to the wider St Winnow streetscape.
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 Lerryn.
01
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
02
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
03
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.
04
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.
Quick check
Want a straight answer on whether your Lerryn 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 Lerryn and the PL22 area.
Our process
How a Lerryn 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
Lerryn Extensions — local questions answered.
- 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. In Lerryn specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
- 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.
- 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.
- We live in the house. Can a extension in Lerryn 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 Lerryn are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
Lerryn is part of Lostwithiel
Lerryn sits inside the Lostwithiel catchment — we cover both as one extension territory.
See Extensions in Lostwithiel →Local proof — Recent extension enquiries from Lerryn have clustered around boat sheds — we know the route through Cornwall Council on these.
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Nearby places we cover
From initial feasibility to final handover, we manage extension projects across Lerryn with careful attention to what makes South Cornwall unique. Here that means the Conservation Area boundary decides the route before the design does.
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