East Cornwall · PL15
Extensions Altarnun: PL15 planning, East Cornwall fabric
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. What works on a PL15 plot rarely works elsewhere — Altarnun is a moorland-edge hamlet in the PL15 area, where exposed weather, narrow lanes and rural character set the brief, with a building stock that leans toward converted barns and isolated houses.
Altarnun sits in East Cornwall — covering PL15 from Launceston, Warbstow, North Petherwin outward.
- Conservation Area
- Rural / open-countryside policy area
- ✓ Cornwall Council regulars across every sub-area
- ✓ Plain-English feasibility before any drawings
- ✓ Measured-survey accuracy from day one
- ✓ One studio — design, planning and build under one roof
Local proof — Recent extension enquiries from Altarnun have clustered around converted barns — we know the route through Cornwall Council on these.
Get a free feasibility viewLocal context
Why Altarnun is its own job.
Rural policy, landscape impact and services such as drainage are usually the key constraints, especially outside settlement boundaries. That sets the scene before any design work begins. For extension specifically, parts of Altarnun sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; Cornwall Council's Local Plan applies tighter tests to isolated rural dwellings here, so design rationale and policy fit need to be set out clearly from the outset. It's the kind of detail that decides whether a Altarnun application gets approved at eight weeks or stalls in committee. The converted barns that dominate Altarnun (and continue out toward North Petherwin) set the tone for any extension scheme here.
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 Altarnun.
01
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
02
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.
03
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
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.
Our process
How a Altarnun 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 fabric
Choosing a extension team that actually knows PL15.
Building stock
Across Altarnun (PL15) we work on stone cottages, farm buildings, isolated houses, converted barns, small rural infill. Each stock type drives a different extension response — converted barns in particular needs careful detailing here.
Parish & policy
Altarnun sits in the parish of Altarnun, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover PL15 from our studio, with regular extension jobs also running in Launceston, Warbstow, North Petherwin. Most Altarnun site visits get booked within the same week.
How quickly can you visit a Altarnun site?
Usually within the same week. Altarnun (PL15) is on our regular East Cornwall run, alongside Launceston, Warbstow, North Petherwin. First visits are free and you'll get an honest feasibility view inside seven days.
Request a free visitFAQs
Altarnun Extensions — local questions answered.
- 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. In Altarnun specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
- 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.
Altarnun is part of Launceston
Altarnun sits inside the Launceston catchment — we cover both as one extension territory.
See Extensions in Launceston →Other services in Altarnun
Nearby places we cover
Designing a extension in Altarnun is as much about reading the parish as reading the brief; we do both, and the planning outcomes follow.