Loft Conversions In Cornwall
Is there a room hiding above your ceiling?
Velux, dormer and hip to gable conversions built and signed off across mid and north Cornwall.
A loft conversion is the only way to add a decent-sized room to a Cornish house without losing garden, moving a drain or arguing with a neighbour about a boundary. The floor area is already there. What you are actually buying is a floor strong enough to stand on, a staircase that satisfies Part K, enough insulation to make the room usable in February, and a roof that stays weathertight where it has been opened up.
Which type of conversion you end up with is decided by the roof, not by preference. We measure the height from the top of the ceiling joists to the underside of the ridge, look at how the roof is framed, and work out where a staircase can physically land before anyone talks about finishes. Trussed roofs, cut roofs and the older purlin roofs common in Cornish stone cottages all behave differently once you start removing bits of them.
Then there is the planning map, which in Cornwall matters more than almost anywhere. Rooflights are usually permitted development even in a conservation area. Dormers are not permitted development on any article 2(3) land, and Cornwall has a great deal of it. We check that on the first visit, for free, before you spend anything on drawings.
Get a free site visit and a written quote
Tell us what you are thinking and we will come and look at it. No charge, and no obligation to go ahead.
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Free site visits
Half an hour, no charge, and a straight answer on whether the space works.
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Structural work in-house
Steels, floors and bearings are our own work, not a subcontractor's problem.
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Building control handled
Full Plans submitted to Cornwall Council, completion certificate at the end.
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One team, start to finish
Same people from first survey to final walk-round. Nobody to chase.
What a loft conversion gives you
The reasons people in Cornwall convert rather than extend, and the ones that only apply here.
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A bedroom without losing garden
Cornish plots are often long and narrow, or cut into a slope, and a single-storey extension eats the flattest part of the garden. A loft takes none of it. On a terrace in Truro or Bodmin, where there may be no realistic extension option at all, it is the only route to a fourth bedroom.
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Up to 24% on the value
Nationwide's October 2025 research found a loft conversion adding a large double bedroom and a bathroom can add up to 24% to a three-bed house. Two bedrooms to three adds 13% on a terrace, 14% on a semi and 17% on a detached. These are national figures - Cornwall-specific ones do not exist, and anyone quoting you one has made it up.
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It usually avoids planning
A rooflight conversion generally stays inside permitted development anywhere in Cornwall, including conservation areas and the World Heritage Site, provided nothing projects more than 150mm beyond the roof slope. That removes an eight-week determination period and a £548 application fee from the programme.
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Bungalows convert brilliantly
Cornwall has 57,920 bungalows, more than any other local authority in England and Wales, and 22,390 of them have two bedrooms. A bungalow roof usually has the volume, the span and the simple structure that makes a conversion straightforward, and the value jump from two beds to three is the biggest there is.
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A quiet room, away from everything
The top of a house is the furthest point from the kitchen and the front door. That is why lofts work so well as a main bedroom with an en-suite, or as a home office you can shut the door on at six o'clock, rather than as a fourth reception room nobody sits in.
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The warm bit of the house gets warmer
An unconverted loft is a cold void that your ceiling insulation is fighting. Bring it inside the heated envelope, insulate the roof slope to 0.15 W/m²K, and the room below gets noticeably warmer as a side effect. On Cornwall's older solid-wall housing this is a real gain, not a sales line.
- Lofts & garages converted
- 250+ Lofts & garages converted
- Structural warranty
- 10 yr Structural warranty
- Site visits & written quotes
- Free Site visits & written quotes
- Team, start to finish
- 1 Team, start to finish
Roughly four out of ten of the roofs we survey turn out to be a different conversion type from the one the customer had in mind when they rang.
How a conversion runs
Seven stages, in this order, every time. The order matters - most of the jobs that go wrong went wrong because someone priced the pretty end before checking the structural end.
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Free site visit
We measure the head height from the top of the ceiling joist to the underside of the ridge, look at how the roof is built, and work out where a staircase can physically land. On a garage we check the floor level, the damp course and how the walls were built. This is the visit that decides whether the job is worth doing at all, and we would rather tell you no at this stage than three weeks in.
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Written quote, with the structure priced in
One document, VAT included, with the structural allowance shown as its own line rather than buried. Where a wall has to be opened up before anyone can be certain what the steel is bearing onto, we say so and give you the range. Exclusions are listed. If your quote from someone else has no structural line on it, that cost has not gone away.
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Planning check before drawings
We check whether your permitted development rights survive. Dormers are not permitted development on article 2(3) land, which in Cornwall means every conservation area, the National Landscape and all ten areas of the Mining World Heritage Site. Rooflights usually still are. Getting this right at the start is the difference between a four-week start and a four-month one.
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Drawings, calculations and building control
Architectural drawings, then a structural engineer sizes the beams and specifies the bearings. We submit Full Plans to Cornwall Council rather than a Building Notice - it costs less in every fee band and it means the details are agreed before anyone cuts anything, instead of being argued about on site.
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Opening up and structural work
Scaffold where the work needs it, then the load-bearing stage: new floor joists sized for a habitable floor rather than a storage loft, steels in, padstones and spreaders bedded properly. On older Cornish stone walls this is where surprises live, which is why it happens early and why we look before we price.
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Weathertight, then first fix
Roof made good, dormer or rooflights in, windows glazed. Once the space is dry it is insulation, electrics, plumbing and the stair. Insulation is worth paying attention to here - the limits for a conversion are tighter than for a new-build house, 0.15 on the roof against 0.16, which catches a lot of people out.
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Plaster, second fix, sign-off and handover
Skim, decorate, doors, sockets, flooring. Then the building control final inspection and your completion certificate, the electrical certificate, and the written structural warranty. We walk the room with you before we take the scaffold down, not after.
What the 10-year warranty actually covers
A conversion is a structural job dressed up as a decorating job. The plasterboard and the paint are the last two weeks of it. Everything that determines whether the room is still sound in twenty years happens before any of that goes on.
The warranty covers the part we control: the structure. Beams sized and signed off by an engineer, bearings that are capable of taking the load, floors that meet their span, and a roof that stays weathertight where we have opened it up. It is written down and handed over with the building control completion certificate at the end of the job, not promised verbally on the doorstep at the start of it.
It matters more here than it would upcountry. A lot of Cornish walls are random rubble stone rather than cavity brickwork, and Eurocode 6, the masonry design standard, explicitly does not cover rubble masonry. There is no code route for dropping a steel onto a wall like that. It has to be justified by an engineer from first principles, which is exactly why we open up and look before we price, rather than after.
What to look for in a loft conversion company
They should measure before they price. Head height is the first thing that decides whether a job is viable, and it is measured from the top of the existing ceiling joists to the underside of the ridge, not floor to ridge. Around 2.2m is comfortable, because the new floor build-up and the new insulated ceiling both take a bite out of it. Below that you are into dormer or roof-raise territory. Anyone who quotes off a photograph or a postcode has not done this.
They should be able to explain the structure, not just the finish. A loft floor is not the same as a ceiling. Existing ceiling joists are sized to hold up plasterboard, not people, so new joists go in alongside them, usually spanning onto new steels rather than onto the old ones. Ask where the steels land and what they bear onto. In Cornwall this is the question that separates the serious quotes from the optimistic ones, because a great many walls here are random rubble stone, and Eurocode 6 explicitly excludes rubble masonry from its scope. There is no standard design route for that bearing. It has to be worked out from first principles by an engineer, and it costs more.
They should tell you where you sit on the planning map before you commit. Cornwall has 145 conservation areas, a National Landscape covering about 27% of the county across twelve separate sections, and all ten areas of the Cornwall and West Devon Mining World Heritage Site. On any of that land, permitted development rights for dormers are gone. There is a second catch: the permitted development volume allowance - 40 cubic metres on a terrace, 50 on anything else - is measured against the roof as it stood in 1948 for older properties, so an earlier dormer someone else added has already spent part of your allowance.
Which type of loft conversion
Four routes into a roof, in rising order of cost and disruption. The right one is normally obvious once someone has been up there with a tape measure.
| Velux / rooflight | Dormer | Hip to gable | Roof raise | |
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| Typical cost (ex VAT) | £30,000 - £45,000 | £45,000 - £75,000 | £55,000 - £85,000 | Can double the dormer cost |
| Head height needed | Good already, 2.2m+ | Marginal, buys it back | Marginal at the hip end | Not enough anywhere |
| Adds floor area | No, uses what exists | Yes, meaningfully | Yes, a whole roof end | Yes, the most |
| Planning in a Cornish conservation area | Usually permitted development | Application needed | Application needed | Almost always needed |
| Time on site | 6 - 8 weeks | 8 - 10 weeks | 10 - 12 weeks | 12 weeks or more |
| Best suited to | Steep older roofs, cottages | Shallow roofs, terraces | Bungalows and semis | Chalet bungalows |
Stairs, en-suites and the bits people forget
The staircase is usually the hardest part of the design and it gets decided first, because everything else works around where it lands. Approved Document K wants 2m of headroom over a stair, but it makes a specific allowance for loft conversions: 1.9m at the centre of the flight and 1.8m at the side is acceptable. That relaxation rescues a lot of Cornish roofs. Maximum pitch is 42 degrees, and a fixed ladder or alternating tread stair is only permitted where the loft contains a single habitable room.
Fire is the other thing that surprises people. Once a new floor sits more than 4.5m above ground level - which is most two-storey houses gaining a third storey - you need a protected escape route all the way down. In practice that means fire doors to minimum E 20 and partitions to REI 30 on the whole stairwell, including upgrading existing doors. On an open-plan ground floor it means either new partitions or a sprinkler system. It is not optional and it is not cheap, so it belongs in the quote from day one.
An en-suite is nearly always worth doing if there is any run for a soil pipe, because Nationwide's figures put the bedroom-plus-bathroom combination well ahead of a bedroom on its own. If your roof is shallow, look at a dormer loft conversion to buy back the standing height an en-suite needs.
Loft conversion costs in Cornwall
Guide ranges before VAT, for work in Cornwall. Every one moves once somebody has been up in the roof.
- Velux / rooflight conversion
- £30,000 - £45,000
- Dormer conversion
- £45,000 - £75,000
- Hip to gable conversion
- £55,000 - £85,000
- Adding an en-suite
- £2,500 - £5,000
- Cornwall Council building control (10-40m²)
- £1,140 inc VAT
Do not assume Cornwall is cheap. Labour is below London by a fair margin, but materials cost the same or slightly more at the end of a ninety-mile peninsula, and the local build factors - rubble walls, exposure, slate matching - push the structural element up rather than down.
Loft conversion questions
- How do I know if my loft can be converted?
- Measure from the top of the existing ceiling joists to the underside of the ridge. Around 2.2m and you are in comfortable territory. Between 2m and 2.2m is usually workable with a dormer to buy back height over the stair. Below about 2m and you are looking at raising the roof, which changes the economics completely. The second thing that matters is how the roof is framed - a modern trussed roof needs the trusses cutting and replacing with a new structural arrangement, which is normal work but it is not free, whereas an older cut roof with purlins often has usable space between the timbers already.
- Do I need planning permission for a loft conversion in Cornwall?
- For rooflights, usually not. Class C of the permitted development order covers roof alterations and, unlike the dormer class, it contains no restriction on article 2(3) land - so a rooflight conversion generally stays permitted development even in a conservation area or the Mining World Heritage Site, provided nothing projects more than 150mm beyond the roof slope. For dormers, Class B applies and it is explicitly unavailable on article 2(3) land. In Cornwall that means 145 conservation areas, the whole Cornwall National Landscape and all ten WHS areas. If you want certainty, Cornwall Council will confirm in writing that your permitted development rights have not been removed for £200, or issue a Lawful Development Certificate for £274.
- Will a loft conversion need building regulations approval?
- Always, without exception. A loft conversion triggers what Approved Document L calls a change to energy status, because a previously unheated space becomes part of the heated dwelling. Beyond that, Part A covers the structure, Part K the stairs, Part B fire escape, Part F ventilation and Part P the electrics. We submit Full Plans to Cornwall Council rather than a Building Notice - it is cheaper in every fee band, £1,140 against £1,248 for a typical conversion, and the details get agreed before anyone starts cutting rather than argued about on site.
- How long will my house be a building site?
- Six to eight weeks on site for a rooflight conversion, eight to ten for a dormer and ten to twelve for a hip to gable. Before any of that there is a design and approval period - drawings, structural calculations and building control - which typically runs four to six weeks, plus eight weeks or more if a planning application is needed. Most of the noisy structural work happens in the first fortnight. Access is usually through a scaffold rather than through your hallway, which keeps the mess out of the house for longer than people expect.
- Does the insulation really have to be that thick?
- Yes, and it is stricter than for a new house, which catches everyone out. Approved Document L Table 4.2 sets the limit for a new roof element in an existing dwelling at 0.15 W/m²K and a new wall at 0.18. The equivalent figures for a brand new build are 0.16 and 0.26. Your conversion is held to a tighter standard than a new-build on the estate down the road. On a dormer it applies to the cheeks as well as the roof. There is a sensible exception: if meeting the wall standard would cost you more than 5% of the room's floor area, a lesser standard can be agreed.
- What happens if my roof is Cornish slate?
- It is handled carefully, because it is worth money and because matching it is not straightforward. Only two quarries in the whole south west still produce roofing slate and both are in Cornwall - Delabole and Trevillet - so a genuine match is possible in a way it is not in most counties. If yours is traditional scantle slating, laid in diminishing courses and bedded in lime mortar, it is a sealed system, and putting an insulated ceiling under it means the batten space has to be ventilated at eaves and ridge or the timbers will rot. That detail gets missed a lot. Slates are set aside and reused wherever they are sound.
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
Find out whether your loft or garage is worth converting
A site visit costs you nothing and takes about half an hour. You will get a straight answer on whether the space works, what it would take, and roughly what it would cost - including the answer nobody wants to give, which is that some roofs are not worth converting.