Loft Conversion Cost In Cornwall
What should you budget?
Real 2026 ranges, plus the Cornwall Council fees that never appear in national cost guides.
Most loft conversion cost guides online are written from London, priced from London, and then presented as national figures. That is not much use if you are in Bodmin. This page gives the underlying build ranges, then adds the specific fees Cornwall Council charges and the local conditions that move the structural element of a quote up or down.
Every figure below carries its source. Where something varies too much to publish a number, we say so rather than inventing one.
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Build cost by conversion type
Excluding VAT. These are the underlying build ranges published by Homebuilding & Renovating and costed by a practising quantity surveyor, which are the most credible free figures available.
| Type | Cost (ex VAT) | What it does |
|---|---|---|
| Velux / rooflight | £30,000 - £45,000 | No change to the roofline. Needs 2.2m of head height already there. |
| Dormer | £45,000 - £75,000 | Buys back head height and floor area. Adds £7,500 - £15,000 over rooflights. |
| Hip to gable | £55,000 - £85,000 | Squares off a hipped end. Usually paired with a rear dormer. |
| Mansard | £70,000 - £120,000+ | Rare around here outside the period townhouses in Truro and Launceston. |
| Roof raise | Roughly double a dormer | Where the ridge is genuinely too low. Almost always needs planning permission. |
By the square metre
Excluding VAT, all conversion types.
- Basic specification
- £1,800 - £2,200 per m²
- Mid specification
- £2,200 - £3,000 per m²
- Premium specification
- £3,000 - £4,000+ per m²
The bungalow number
The national average for a bungalow loft conversion is around £75,000 - the highest of any property type, ahead of detached at £62,500 and semi-detached at £50,000. It is the most relevant national figure there is for Cornwall, because the county has 57,920 bungalows, more than any other local authority in England and Wales, and 22,390 of them have just two bedrooms.
The Cornwall fees nobody else lists
These come straight off Cornwall Council's published schedules. They are not estimates and they are not included in any national cost guide.
- Cornwall Council building control, 10 - 40m² (Full Plans)
- £1,140 inc VAT
- Cornwall Council building control, 40 - 150m² (Full Plans)
- £1,398 inc VAT
- Building Notice instead of Full Plans, 10 - 40m²
- £1,248 inc VAT
- Householder planning application (from 1 April 2026)
- £548
- Lawful Development Certificate, proposed use
- £274
- Council confirmation that PD rights survive
- £200
- Listed building consent
- No fee
- Scaffolding licence for the highway, per calendar month
- £157
- Structural engineer's calculations
- £750 - £1,500
- En-suite shower room
- £2,500 - £5,000
Planning fees rose 3.8% on 1 April 2026 and a new national fee schedule takes effect on 8 December 2026, so anything quoted here should be re-checked after that date. Building control fees include VAT; planning fees are not VATable.
What moves the price here
Five things that are different about pricing a loft conversion in Cornwall.
What your walls are made of
Cornwall has over 97,000 solid-wall properties, roughly a third of its housing stock, and 27.7% of it predates 1919 against 20.2% across England. Granite, killas, cob and hollow slate-hung construction are all normal. Eurocode 6 does not cover rubble masonry, so there is no standard design route for a steel bearing onto one - it needs an engineer working from first principles, and conservative padstones. Budget more engineering time on an older property than on a postwar one.
Whether you need planning permission
Not just the £548 fee - the eight-week determination, the drawings prepared to a different standard, and the risk of a refusal. Dormers lose permitted development on all article 2(3) land, which in Cornwall is 145 conservation areas, 27% of the county in the National Landscape and ten World Heritage Site areas. A rooflight conversion usually avoids all of it.
Where the scaffold has to stand
On a detached bungalow with a drive, nothing. On a terraced cottage in Port Isaac or Fowey where the scaffold must go on the pavement, a Cornwall Council licence at £157 a month, £5m public liability cover, and a minimum two-week lead time before anyone can start.
What is on your roof
Concrete tile is straightforward. Natural slate costs more to strip and reinstate, and traditional Cornish scantle slating costs more again, because it is triple-lapped so there are more slates per square metre, and because Cornwall Council's own guidance notes there are relatively few contractors with the skills - its 2007 survey listed six in the whole county. The upside is that Delabole and Trevillet still quarry here, so matching is possible.
How exposed the site is
The whole of Cornwall sits in Zone 4, "very severe", for wind-driven rain under Approved Document C, at 100 litres per square metre or more per storm spell. London is Zone 1. That drives dormer cladding toward slate hanging rather than render on board. Within a few miles of the coast it also drives fixings to grade 316 stainless rather than 304, which has a documented failure history in marine conditions.
Before you compare quotes: a loft conversion inside an existing house is standard-rated at 20% VAT. The 5% reduced rate applies only where the number of dwellings changes, or where the property has stood empty for at least two years - and occasional use as a second home disqualifies it from the empty-home route. Zero-rating for approved alterations to listed dwellings was abolished on 1 October 2012.
Loft conversion cost questions
- Is a loft conversion cheaper in Cornwall than in London?
- The labour is, and the materials are not. A quantity surveyor writing for Homebuilding & Renovating puts South East and London projects at 15% to 30% more than comparable work elsewhere, and that gap is almost entirely labour. Materials are a different story - the same source notes material costs vary only marginally across the UK, because delivery over longer distances to more remote locations evens things out. At the end of a ninety-mile peninsula that can tip slightly the other way. Two Cornish trade sources say the county sits at or a little above the national average once travel and limited local trade availability are counted. So the honest answer is that you save on labour against London, you save little or nothing against the national average, and Cornish site conditions can push the structural element up.
- What is the biggest single variable in a quote?
- The structure, and specifically what the new steels bear onto. On a 1970s cavity-walled semi this is routine and can be priced accurately from a survey. On the older stone housing that makes up a lot of Cornwall, it cannot always be, because a great many walls here are random rubble granite or killas and Eurocode 6 explicitly excludes rubble masonry from its scope. There is no code design route for that bearing, so an engineer has to justify it from first principles with conservative padstones and spreaders. Historic England's guidance on solid walls describes the reason well: voids, irregular bonding patterns and concealed timbers. You cannot price with certainty until you have opened up.
- How much does building control cost in Cornwall?
- Cornwall Council publishes its domestic fees and they include VAT. For a loft conversion between 10 and 40 square metres, which is most of them, Full Plans costs £1,140 in total - £480 for the plan check and £660 for inspections - against £1,248 for a Building Notice. Between 40 and 150 square metres it is £1,398 on Full Plans. Full Plans is cheaper than a Building Notice in every band, and it also means the details are agreed before work starts rather than argued about on site, so it is what we submit. Regularisation of work already done without approval is charged at the Building Notice net fee plus 40%.
- Do I have to pay for planning permission?
- Only if you need it, and for a rooflight conversion you usually do not. Where an application is required - which means any dormer or hip to gable on article 2(3) land - a householder application costs £548 from 1 April 2026, up from £528 the previous year. A Lawful Development Certificate for a proposed use, which is the belt-and-braces route when you believe the work is permitted development, costs half a full application at £274. Listed building consent carries no fee at all. Note that a new national fee schedule takes effect on 8 December 2026, so figures quoted now should be re-checked after that date.
- Are there hidden costs people forget?
- Four come up repeatedly. Scaffolding on a public pavement needs a Cornwall Council licence at £157 per calendar month with £5m public liability cover and a minimum two-week lead time, which matters on the narrow streets in Truro, Padstow, Fowey and Port Isaac. Fire safety upgrades to the existing staircase are frequently missed - once the new floor is above 4.5m you need a protected route with E 20 doors throughout, which can mean replacing doors on floors you were not touching. Decoration and floor coverings are often excluded from quotes. And if more than 25% of the roof area is being replaced, there is a legal duty to notify building control about upgrading insulation to Part L.
- Will the conversion pay for itself?
- In most of Cornwall on most conversions, yes, but not everywhere and it is worth being honest about why. Nationwide's 2025 research puts a loft conversion adding a large double bedroom and bathroom at up to 24% of a three-bed house's value. The catch is that the uplift is a percentage of your local house price while the build cost is roughly national. Land Registry figures give an average of about £514,000 in Padstow and about £233,000 in Launceston - so the same 24% is worth well over twice as much in one place as the other. On a large conversion in a lower-priced inland town the sums can be marginal. We will tell you if we think that is your situation.
What customers say
Conversions across mid and north Cornwall, from Victorian terraces in Truro to bungalows on the coast road.
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We had been told twice that our roof pitch was too shallow for a loft. The survey here came back the same, but with an actual option - a rear dormer to buy back the headroom over the stair. They measured 1.9m at the centre of the flight and showed us where that sat against the regs before we spent anything. Two bedrooms and a shower room now.
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Ours is an old miner's terrace and the walls are random rubble, not cavity. They were straight with us that the steel bearings would need opening up before anyone could price it properly, and they got the engineer out first rather than guessing. Cost more than a modern semi would have, but nothing on the quote changed from start to finish.
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We're inside the mining World Heritage Site so a dormer was never going to fly. They knew that on the first visit and steered us to conservation rooflights instead, which kept us out of a planning application altogether. The slate was matched properly too - you cannot tell where the new work stops.
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Integral garage into a snug and a utility. What sold me was that they explained the floor build-up - the damp membrane, the insulation, why the finished floor ends up a couple of inches higher than the hall. Every other quote just said 'convert garage'. Warm room, no condensation, and it was done in under four weeks.
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Terraced house on a hill, so the scaffold had to go on the pavement. They sorted the licence with Cornwall Council and gave us the two-week lead time up front instead of turning up and discovering it. Small thing but it tells you how the rest of the job went.
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A proper annexe for my mum, and honest advice on the bits I would never have thought about - that the council tax discount depends on who lives there, and that a planning condition tying it to the main house would knock out the reduced VAT rate. They flagged it before we committed rather than after.
Where we work
We work within about twenty-five miles of Wadebridge, which covers the north coast, the Camel and Fowey valleys, mid Cornwall and down as far as Truro. We would rather be on your job properly than spend two hours a day driving to it. If your village is not listed, ring us - if it is in the area, the answer is yes.
- Wadebridge
- Padstow
- Bodmin
- Newquay
- Truro
- St Austell
- St Agnes
- Liskeard
- Launceston
- Bude
- Perranporth
- Camelford
- Tintagel
- Delabole
- Port Isaac
- Rock
- St Columb Major
- Lostwithiel
- Fowey
- Looe
Get a real number for your roof
Ranges only get you so far. A free site visit gives you a written quote with VAT included, the structural allowance shown separately, and the exclusions listed.