East Cornwall · PL18
Extensions for Calstock (PL18)
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 Calstock starts with a measured walk-round — Calstock is a creekside settlement in the PL18 area, with waterside homes, wooded valleys and narrow-lane access shaping the brief, with a building stock that leans toward creekside cottages and boat sheds.
Calstock sits in East Cornwall — covering PL18 from Callington, Stoke Climsland, Linkinhorne outward.
- Conservation Area
- Cornish Mining World Heritage Site
- ✓ Same team on paper as on site
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Local to East Cornwall — not a national franchise
- ✓ One studio — design, planning and build under one roof
Our process
How a Calstock 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.
Local proof — We typically have one or two extension jobs live in the PL18 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewWhat we focus on
Extensions considerations specific to Calstock.
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
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
04
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.
Local context
Why Calstock is its own job.
In Calstock the planning picture is specific: creekside ecology, flood risk, trees and views across the water often matter as much as the building form itself. For extension specifically, parts of Calstock 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. That local reading is what makes a Calstock (PL18) project different from a generic Cornwall scheme — and is the whole reason we work this way. On creekside cottages in particular — the kind you'll also find toward Gunnislake — 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.
Local watch-list
The PL18 constraints that shape a extension brief.
Watch #1
Conservation Area material and fenestration controls in central Calstock
Watch #2
World Heritage Site assessment on changes visible in the mining landscape
Calstock is part of Callington
Calstock sits inside the Callington catchment — we cover both as one extension territory.
See Extensions in Callington →Local fabric
One PL18 studio, one extension job — start to finish.
Building stock
Across Calstock (PL18) we work on creekside cottages, detached houses, boat sheds, converted barns, waterside homes. Each stock type drives a different extension response — creekside cottages in particular needs careful detailing here.
Parish & policy
Calstock sits in the parish of Calstock, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover PL18 from our studio, with regular extension jobs also running in Callington, Stoke Climsland, Linkinhorne. Most Calstock site visits get booked within the same week.
Can you handle both planning and build in Calstock?
Yes — design, planning, building regs and full construction run under one roof. For clients with an existing Calstock builder we can stop at a tender-ready Full Plans pack instead.
Request a free visitWho this is for
Calstock runs the full mix — owner-occupier, holiday-let, commercial and the occasional smallholding — so we scope every extension enquiry from the use-class up.
FAQs
Calstock 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 Calstock 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.
- 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.
- 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.
- Do I need planning permission for an extension?
- Often no — single-storey rear extensions, side extensions and modest two-storey additions can sit inside permitted development on a typical detached house. Conservation Areas, AONB and Article 4 zones remove some of those rights, so we always check the address first.
Other services in Calstock
Nearby places we cover
The PL18 stretch of East Cornwall has its own rhythm; our extension work respects it, and Cornwall Council usually responds in kind.