Penwith · TR20 · Cornwall Council West
New Mill extension — feasibility first, drawings second
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. On a New Mill site, the brief always meets the place — New Mill is a small rural hamlet in the TR20 area, with scattered homes, lanes and a deliberately quiet settlement pattern, with a building stock that leans toward small infill homes and converted barns.
New Mill sits in Penwith — just off the A30; covering TR20 from Penzance, Chyandour, Sancreed outward.
- Rural / open-countryside policy area
- ✓Cornwall Council West sub-area regulars
- ✓Free first site visit, no obligation
- ✓Plain-English feasibility before any drawings
- ✓30+ years of Cornwall Council approvals
Free · No obligation
Free New Mill feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Who this is for
In New Mill 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 watch-list
New Mill-specific issues we screen on the first visit.
Watch #1
Local Plan tests on isolated dwellings, plus lane access for plant and deliveries around New Mill
Watch #2
Party Wall notices and shallow roof voids typical of cottages in the TR20 district
Local proof — Most New Mill homeowners come to us after a extension quote elsewhere felt vague on planning — we lead with feasibility instead.
Get a free feasibility viewFAQs
New Mill Extensions — local questions answered.
- We live in the house. Can a extension in New Mill 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 New Mill are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
- 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 New Mill specifically, we'd start by checking the latest parish-level planning history 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.
- 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.
- 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.
Quick check
Want a straight answer on whether your New Mill 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 New Mill and the TR20 area.
Scope
What we can draw, survey and build around New Mill
These stages can be bought separately. Most TR20 projects use three of them.
Planning application drawings
Existing and proposed plans, elevations, site and block plans drawn to validation standard.
Construction and technical drawings
1:10 and 1:20 details for the parts of the job builders normally have to guess at.
Structural coordination
Calculations coordinated with the drawings so building control sees one consistent story.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
Full design and build
One contract from first sketch to handover, with the same team on paper and on site.
Page purpose
Drawings only, or drawings through to handover in New Mill?
Both routes are open on a TR20 project, and the honest answer depends on whether you already have a builder you trust. Plenty of New Mill 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 TR20 scope, not as one opaque figure
Keep reading
Follow the chain: survey, drawings, build
New Mill is covered from our Penzance 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.
Who this is for
Why this page exists, and who it is for
- Applications for New Mill are handled through Cornwall Council, with Truro the nearest planning office we deal with regularly.
- Design and build are offered from the same studio, which means the person answering your New Mill 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.
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.
Local context
Why New Mill is its own job.
Locally, the main planning test is usually whether the proposal remains subordinate, locally detailed and acceptable on access, drainage and neighbour amenity. 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. Which is why we scope New Mill projects parish-up, not template-down — the TR20 context shapes the design from day one. Whether the project is on small infill homes in the centre or further out toward Penzance, the extension response is locally tuned.
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 New Mill.
01
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.
02
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
03
Wind and sea-spray exposure can drive material choices on west-facing extensions; we detail accordingly.
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.
Our process
How a New Mill 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 TR20.
Building stock
Across New Mill (TR20) we work on cottages, farmhouses, converted barns, bungalows, small infill homes. Each stock type drives a different extension response — small infill homes in particular needs careful detailing here.
Parish & policy
New Mill sits in the parish of New Mill, which matters for how parish-level consultation lands on a extension application.
Coverage
We cover TR20 from our studio, with regular extension jobs also running in Penzance, Chyandour, Sancreed. Most New Mill site visits get booked within the same week.
What does a first New Mill consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a TR20 plot and follow up with a written feasibility note inside a week — no obligation either way.
Request a free visitNew Mill is part of Penzance
New Mill sits inside the Penzance catchment — we cover both as one extension territory.
See Extensions in Penzance →Other services in New Mill
Nearby places we cover
Designing a extension in New Mill is as much about reading the parish as reading the brief; we do both, and the planning outcomes follow. farmhouses in particular need a tailored structural answer.
One conversation — and a clearer New Mill brief We know how cottages behave here.
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