Mid Cornwall · TR4
Twelveheads loft conversion — feasibility first, drawings second
A well-designed loft conversion adds a bedroom, an en-suite and useful storage to homes that were never built with the upper floor in mind — usually inside permitted development and almost always cheaper per square metre than extending sideways. On a Twelveheads site, the brief always meets the place — Twelveheads is a former mining settlement in the TR4 area, with granite terraces, chapel buildings and industrial landscape character still visible, with a building stock that leans toward granite terraces and post-war estates.
Twelveheads sits in Mid Cornwall — covering TR4 from Truro, St Michael Penkivel, Calenick outward.
- Cornish Mining World Heritage Site
- Rural / open-countryside policy area
- ✓ 30+ years of Cornwall Council approvals
- ✓ World Heritage Site experience built into the fee
- ✓ Cornwall Council regulars across every sub-area
- ✓ Free first site visit, no obligation
Who this is for
Twelveheads runs the full mix — owner-occupier, holiday-let, commercial and the occasional smallholding — so we scope every loft conversion enquiry from the use-class up.
Local watch-list
Local snags worth knowing before drawing a Twelveheads loft conversion.
Watch #1
World Heritage Site assessment on changes visible in the mining landscape
Watch #2
Tighter Local Plan tests on isolated rural dwellings
Local proof — We typically have one or two loft conversion jobs live in the TR4 area at any time, so the local planning officers know our drawings on sight.
Get a free feasibility viewFAQs
Twelveheads Loft Conversions — local questions answered.
- Will I have enough headroom?
- We need a minimum 2.2 metres ridge-to-joist before alterations to make a usable conversion straightforward. Less than that and we'd consider raising the ridge, which is a planning conversation, not a permitted development one. In Twelveheads specifically, we'd start by checking the latest parish-level planning history before committing to a direction.
- Will it add value?
- An extra bedroom and bathroom typically adds noticeably more value than the build cost in most Cornish markets — but the value matters less than the daily use you'll get from the space.
- How much does a loft conversion cost?
- A simple Velux conversion starts around £30,000 in Cornwall; a rear dormer with en-suite typically runs £45,000 to £65,000; hip-to-gable and mansards more. Stair location and bathroom complexity drive most of the cost.
- How long does a loft conversion take?
- Allow six to ten weeks on site for a Velux conversion, eight to fourteen weeks for a dormer, twelve to eighteen weeks for hip-to-gable. Add four to eight weeks for design and regs beforehand.
- Do I need planning permission for a loft conversion?
- Often no — most loft conversions sit inside permitted development on a typical Cornish house. Conservation Areas, AONB and properties on principal elevations need full planning, and we'll confirm at first review.
Local context
Why Twelveheads is its own job.
Locally, mining heritage, old plot widths and traditional materials make proportion and detailing more important than generic extension templates. For loft conversion specifically, the wider area forms part of the Cornish Mining World Heritage Site, which adds a heritage assessment layer to most material changes; 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 Twelveheads projects parish-up, not template-down — the TR4 context shapes the design from day one. Whether the project is on granite terraces in the centre or further out toward Truro, the loft conversion response is locally tuned.
Planning note
Most Cornish loft conversions are permitted development — but a Certificate of Lawfulness is worth the extra week and small fee for resale protection.
What we focus on
Loft Conversions considerations specific to Twelveheads.
01
Stairs eat space — a loft conversion lives or dies by where the new staircase lands and what it costs you on the floor below.
02
Cut-roof Cornish properties are easier to convert than modern trussed roofs; the structural strategy varies completely.
03
Cornish slate roofs come in a huge range of pitches — anything below a 30° pitch struggles to give usable headroom without raising the ridge.
04
Permitted development volume allowances are 40 cubic metres on a terrace and 50 on a detached or semi — but rear dormers in Conservation Areas often need full planning.
Our process
How a Twelveheads loft conversion project runs.
Step 1
Feasibility
Roof, headroom, stair landing and structural assessment.
Step 2
Design
Layout options that respect the staircase, headroom and bathroom positioning.
Step 3
Approvals
Planning or permitted development confirmation, plus building regs.
Step 4
Build
Sequenced to keep the family living downstairs throughout most of the work.
Step 5
Handover
Finish, snag, certify, hand over the keys.
Loft conversions typically run six to eighteen weeks on site depending on type, with four to eight weeks of design and approvals beforehand.
Local fabric
Why Twelveheads homeowners pick a local studio for loft conversion.
Building stock
Across Twelveheads (TR4) we work on miners cottages, granite terraces, chapel conversions, workers cottages, post-war estates. Each stock type drives a different loft conversion response — granite terraces in particular needs careful detailing here.
Parish & policy
Twelveheads sits in the parish of Twelveheads, which matters for how parish-level consultation lands on a loft conversion application.
Coverage
We cover TR4 from our studio, with regular loft conversion jobs also running in Truro, St Michael Penkivel, Calenick. Most Twelveheads site visits get booked within the same week.
What does a first Twelveheads consultation cost?
Nothing. We come to the property, walk the site, talk through what works on a TR4 plot and follow up with a written feasibility note inside a week — no obligation either way.
Request a free visitTwelveheads is part of Truro
Twelveheads sits inside the Truro catchment — we cover both as one loft conversion territory.
See Loft Conversions in Truro →Other services in Twelveheads
Nearby places we cover
From initial feasibility to final handover, we manage loft conversion projects across Twelveheads with careful attention to what makes Mid Cornwall unique.