West Cornwall · TR19 · Cornwall Council West
Small rear extensions in Mousehole — under-3m designs that work hard
A Mousehole rear extension under 3m doesn't need to feel small. The compact TR19 terraces and cottages we work on benefit most from a single tight move: a glazed corner, a side-light over the new kitchen, or a re-jigged level threshold to the garden. Under-3m and single-storey usually sits inside permitted development, which removes most of the planning risk. 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 Mousehole site, the brief always meets the place — Mousehole is a famously photogenic fishing village south of Newlyn, almost entirely within the Conservation Area and AONB, with a tiny harbour and dense lanes of granite cottages, with a building stock that leans toward granite fishing cottages and converted net-lofts.
Mousehole sits in West Cornwall — just off the A30; covering TR19 from Newlyn, Paul outward.
- Conservation Area
- Cornwall AONB
- Coastal exposure zone
- ✓Under-3m PD route — no planning needed
- ✓Glazed corner detailing maximises light gain
- ✓Typical 8–15m² build: £30k–£55k
- ✓On-site build: 10–14 weeks
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Free Mousehole feasibility call
Tell us about your extension. We reply within 1 working day — no obligation.
Who this is for
In Mousehole 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
Local snags worth knowing before drawing a Mousehole extension.
Watch #1
Conservation Area controls on materials, window proportions and roof form through central Mousehole
Watch #2
AONB landscape-impact testing on anything read in long views across West Cornwall
Watch #3
Exposure detailing on granite fishing cottages — fixings, render systems and joinery specified for salt-laden air
Watch #4
Party Wall notices and shallow roof voids typical of granite fishing cottages in the TR19 district
Local proof — Most Mousehole extension clients we work with are second-time builders — they've seen the templated approach fail once already.
Get a free feasibility viewFAQs
Mousehole Extensions — local questions answered.
- What's the smallest worthwhile rear extension in Mousehole?
- Anything from 8m² is worth doing if it unlocks a kitchen layout. Below that, the cost per m² makes a glazed door upgrade more sensible.
- Can I do a small extension in Mousehole under permitted development?
- If the property has its PD rights intact, single-storey rear extensions up to 3m (terraced/semi) or 4m (detached) are permitted. Conservation Area sites lose this — full planning needed.
- How much does a small extension cost in Mousehole?
- For 8–15m² in Mousehole, allow £30k–£55k including a basic kitchen refit. Coastal detailing and salt-resistant ironmongery add 5–8%.
- We live in the house. Can an extension in Mousehole 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 Mousehole are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
- 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. In Mousehole 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.
Quick check
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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 Mousehole and the TR19 area.
Who this is for
Why this page exists, and who it is for
- Drawings, planning and building regulations are all produced in-house, so an extension enquiry does not get passed between firms.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
- Applications for Mousehole are handled through Cornwall Council, with Truro the nearest planning office we deal with regularly.
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.
Keep reading
Follow the chain: survey, drawings, build
Mousehole is covered from our Newlyn 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.
Page purpose
Drawings only, or drawings through to handover in Mousehole?
Both routes are open on a TR19 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Mousehole 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 TR19 scope, not as one opaque figure
Scope
What we can draw, survey and build around Mousehole
Clients in Mousehole take different slices of this list, and that is deliberate.
Full design and build
One contract from first sketch to handover, with the same team on paper and on site.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
Construction and technical drawings
1:10 and 1:20 details for the parts of the job builders normally have to guess at.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Building regulation drawings
Full Plans sets with sections, construction notes and coordinated structural information.
Local context
Why Mousehole is its own job.
Locally, almost the entire village is within both the Conservation Area and AONB; new openings, dormers, render colours and roof materials all attract close scrutiny. Paul parish operates with strong policy resistance to second-home use. For extension specifically, parts of Mousehole 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 Mousehole drives detailing choices — fixings, render systems and timber treatments all need to be specified for exposure. Which is why we scope Mousehole projects parish-up, not template-down — the TR19 context shapes the design from day one. Whether the project is on granite fishing cottages in the centre or further out toward Paul, the extension response is locally tuned. Where a property sits inside a conservation area or is listed, the assessment tends to turn on materials, window detailing and how visible the change is from the street rather than floor area alone. Cornwall Council's conservation team, or the Planning Portal, is the right place to confirm what applies to a specific address. Coastal sites tend to raise questions about roof form, glazing exposure and how a scheme reads from public viewpoints. Those are policy judgements rather than fixed rules, so the local planning authority or the Planning Portal should confirm the position for a given plot.
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 Mousehole.
01
Cornish granite and slate-hung walls react differently to new openings than modern brickwork — lintel choice and structural sequencing matter.
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
Drainage on older Cornish properties is rarely on a clean modern map; CCTV survey before design is often money well spent.
Our process
How a Mousehole 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
Why Mousehole homeowners pick a local studio for extension.
Building stock
Across Mousehole (TR19) we work on granite fishing cottages, Victorian villas above the village, modern infill carefully matched to traditional vernacular, converted net-lofts. Each stock type drives a different extension response — granite fishing cottages in particular needs careful detailing here.
Parish & policy
Mousehole sits in the parish of Paul, which matters for how parish-level consultation lands on an extension application.
Coverage
We cover TR19 from our studio, with regular extension jobs also running in Penzance. Most Mousehole site visits get booked within the same week.
What does a first Mousehole consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a TR19 plot and follow up with a written feasibility note inside a week — no obligation either way.
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Nearby places we cover
Small extensions in Mousehole succeed on detailing, not scale. A well-placed rooflight and the right floor finish often deliver more than an extra metre of footprint.
Sketch a small Mousehole extension that punches above its size
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