Mid Cornwall · TR4
House Extensions in Zelah
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. A Zelah brief starts on the street, not the screen — Zelah is a commuter village in the TR4 area, with everyday family housing, edge-of-village plots and quick routes to its parent town, with a building stock that leans toward garden infill plots and bungalows.
Zelah sits in Mid Cornwall — covering TR4 from Truro, St Michael Penkivel, Calenick outward.
- Rural / open-countryside policy area
- ✓ Local to Mid Cornwall — not a national franchise
- ✓ Same team on paper as on site
- ✓ Fixed-fee planning packages, no surprise invoices
- ✓ Measured-survey accuracy from day one
Local watch-list
Zelah-specific issues we screen on the first visit.
Watch #1
Tighter Local Plan tests on isolated rural dwellings
Who this is for
Zelah runs the full mix — owner-occupier, holiday-let, commercial and the occasional smallholding — so we scope every extension enquiry from the use-class up.
Local context
Why Zelah is its own job.
Applications here usually turn on neighbour amenity, parking, overlooking and whether new work fits the rhythm of existing streets. For extension specifically, 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. So every Zelah job runs as a TR4-specific piece of work — local policy, local fabric, local builders. Most of our extension work in Zelah lands on garden infill plots, with detailing that has to nod to the wider St Michael Penkivel 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 Zelah.
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
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 Zelah 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
Zelah Extensions — local questions answered.
- How much does an extension cost in Zelah?
- 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. In Zelah specifically, we'd start by checking the latest parish-level planning history before committing to a direction.
- 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.
- 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.
- Will my house be liveable during the build?
- For most rear and side extensions, yes — we sequence the works so the kitchen and one bathroom stay functional until the new build is watertight and connected.
- 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.
Zelah is part of Truro
Zelah sits inside the Truro catchment — we cover both as one extension territory.
See Extensions in Truro →Local proof — We typically have one or two extension jobs live in the TR4 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewOther services in Zelah
Nearby places we cover
For Zelah homeowners weighing up a extension, the right starting point is honest feasibility — that's what we lead with, before any drawings.