Mid Cornwall · TR15 · Cornwall Council West
House extension costs in Redruth — what TR15 homeowners actually pay
Most Redruth cost questions land in the same bracket: a single-storey rear sits roughly £2,200–£2,800/m² built, a two-storey side runs £2,000–£2,500/m², and anything touching a stone-fronted elevation tends to add 8–12% for materials and detailing. We quote on measured drawings, not guesses. 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 Redruth version of this work has its own character — Redruth shares the Cornish Mining World Heritage status with neighbouring Camborne, with the granite outcrop of Carn Brea as its backdrop and a steep, terraced town centre dropping down to Fore Street, with a building stock that leans toward miners' cottages and Wesleyan chapels and former chapels.
Redruth sits in Mid Cornwall — just off the A30; with Truro the closest city; 4 miles from Camborne.
- Conservation Area
- Cornish Mining World Heritage Site
- ✓Typical Redruth single-storey rear: £55k–£85k build cost
- ✓Two-storey side extension: £85k–£140k build cost
- ✓Wrap-around / L-shaped: £110k–£180k build cost
- ✓Design + planning + building regs fee from £4,800 (fixed)
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Local watch-list
The TR15 constraints that shape an extension brief.
Watch #1
World Heritage Site assessment on principal elevations facing the mining landscape
Watch #2
Shallow-pitched Cornish slate roofs limiting loft headroom
Watch #3
Party Wall awards on dense Victorian terraces
Watch #4
Below-ground voids from historic mining requiring structural caution
Who this is for
In Redruth 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.
Scope
The parts of the job we can take on in Redruth
Clients in Redruth take different slices of this list, and that is deliberate.
Building regulation drawings
Full Plans sets with sections, construction notes and coordinated structural information.
Planning application drawings
Existing and proposed plans, elevations, site and block plans drawn to validation standard.
Measured survey
An accurate record of what is actually there, which is where most avoidable cost is removed.
Heritage and design statements
Written justification where designation makes the design case as important as the drawing.
Structural coordination
Calculations coordinated with the drawings so building control sees one consistent story.
Who this is for
What we can genuinely back up in Redruth
- Design and build are offered from the same studio, which means the person answering your Redruth questions has seen the detail built.
- Commercial and mixed-use work in Redruth tends to sit around Cardrew Industrial Estate.
- Applications for Redruth are handled through Cornwall Council, with Truro the nearest planning office we deal with regularly.
- Designated-area work is routine here, so heritage and landscape statements are produced alongside the drawings rather than outsourced.
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
Other work we do around Redruth
We cover Redruth and the wider TR15 district directly, typically alongside jobs in Camborne. Extensions enquiries here are common enough that we know the constraints before the first visit.
Page purpose
Drawings only, or drawings through to handover in Redruth?
Both routes are open on a TR15 project, and the honest answer depends on whether you already have a builder you trust. Plenty of Redruth 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 TR15 scope, not as one opaque figure
Local context
Why Redruth is its own job.
Conservation Area coverage runs through Fore Street, West End and Clinton Road; Carn Brea and the surrounding mining landscape add a heritage layer over much of the town's edges. World Heritage assessment is part of most non-trivial applications. For extension specifically, parts of Redruth sit within a designated Conservation Area, which means materials, fenestration and roof pitches all need to read sympathetically with the existing streetscape; the wider area forms part of the Cornish Mining World Heritage Site, which adds a heritage assessment layer to most material changes. So every Redruth job runs as a TR15-specific piece of work — local policy, local fabric, local builders. Most of our extension work in Redruth lands on miners' cottages, with detailing that has to nod to the wider Camborne streetscape. 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. On working land, the practical questions are usually track access for deliveries, foul drainage and how a new form sits in open landscape. General guidance only, so confirm your position with Cornwall Council before committing.
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 Redruth.
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
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.
Quick check
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For projects in Redruth and the TR15 area.
Recent work nearby
Recent West End terrace loft conversion squeaked through at 2.15m ridge-to-joist with a slim ridge raise.
See more recent Mid Cornwall work →Our process
How a Redruth 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
Redruth Extensions — local questions answered.
- What's the average cost of a single-storey extension in Redruth?
- For a typical 20–30m² rear extension in Redruth (TR15) we'd expect £55k–£85k including VAT, depending on glazing spec and whether the kitchen is being reworked. Coastal exposure here pushes weather-tightness specs up, which is real money.
- Do extension costs in Redruth include planning and building regs?
- Our fixed-fee design package covers measured survey, planning drawings, building regs and a tendered cost plan. Build cost is separate and quoted from drawings — never guessed from a phone call.
- What pushes a Redruth extension over budget?
- Three things: ground conditions you didn't survey for, a planning condition that drives a material change, and "while we're at it" scope creep. We screen all three at feasibility stage so the number you start with is the number you finish on.
- 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. In Redruth specifically, we'd start by checking the Conservation Area boundary before committing to a direction.
- We live in the house. Can an extension in Redruth 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 Redruth are often easier if you move out for a few weeks. We set that expectation at feasibility stage rather than halfway through.
- 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.
Local proof — We typically have one or two extension jobs live in the TR15 area at any time, so the local planning officers know our drawings on sight.
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