South Cornwall · TR11 · Cornwall Council Central
Extensions for Mawnan Smith (TR11)
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 Mawnan Smith starts with a measured walk-round — Mawnan Smith is an AONB village south of Falmouth between the Helford River and Maenporth Beach, with a strong period property market and a tight Conservation Area at its centre, with a building stock that leans toward high-end modern architect builds and Edwardian houses.
Mawnan Smith sits in South Cornwall — just off the A39; with Truro the closest city; 3 miles from Falmouth.
- Conservation Area
- Cornwall AONB
- Coastal exposure zone
- Rural / open-countryside policy area
- ✓One studio — design, planning and build under one roof
- ✓Local to South Cornwall — not a national franchise
- ✓Measured-survey accuracy from day one
- ✓Plain-English feasibility before any drawings
Free · No obligation
Free Mawnan Smith feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Local watch-list
Mawnan Smith-specific issues we screen on the first visit.
Watch #1
Helford River AONB across the whole parish
Watch #2
Rural-policy tests on isolated dwellings
Watch #3
Subtropical-garden microclimates affecting orientation choices
Watch #4
Narrow lane access for plant and crane
Who this is for
In Mawnan Smith 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.
Local context
Why Mawnan Smith is its own job.
In Mawnan Smith the planning picture is specific: conservation Area covers the village core; AONB across the parish. Helford River views and ecology constraints shape applications on the southern edge. For extension specifically, parts of Mawnan Smith sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; the surrounding landscape falls inside the Cornwall Area of Outstanding Natural Beauty, so massing, height and landscape impact carry extra weight in any planning decision; coastal salt-laden air around Mawnan Smith drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure; 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. That local reading is what makes a Mawnan Smith (TR11) project different from a generic Cornwall scheme — and is the whole reason we work this way. On high-end modern architect builds in particular — the kind you'll also find toward Durgan — 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.
What we focus on
Extensions considerations specific to Mawnan Smith.
01
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
02
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
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 Mawnan Smith 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.
Free · No obligation
Get a free feasibility view
For projects in Mawnan Smith and the TR11 area.
Recent work nearby
Recent Helford-side replacement dwelling stepped down two terraces to clear protected long views.
See more recent South Cornwall work →Our process
How a Mawnan Smith 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
Mawnan Smith Extensions — local questions answered.
- 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 Mawnan Smith specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- 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.
- 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.
- 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.
Mawnan Smith is the hub for these neighbourhoods
We run extensions across Mawnan Smith and the surrounding TR11 neighbourhoods — same studio, same site team.
Local proof — Most Mawnan Smith homeowners come to us after a extension quote elsewhere felt vague on planning — we lead with feasibility instead.
Get a free feasibility viewOther services in Mawnan Smith
Nearby places we cover
The TR11 stretch of South Cornwall has its own rhythm; our extension work respects it, and Cornwall Council usually responds in kind.
Pencil in a free Mawnan Smith visit this week
Free · No obligation
Book a free visit in Mawnan Smith
No obligation. Reply usually same working day.