Velux Loft Conversions In Cornwall
Does your roof already have the height you need?
Rooflights fitted flush into the existing slope - the cheapest route into a loft, and the one that keeps your permitted development rights.
A Velux conversion, more properly a rooflight conversion, leaves the shape of your roof completely alone. Nothing is built outward, nothing projects, and the roofline stays exactly as it is. The windows sit flush in the slope, the floor is strengthened, the roof is insulated from the inside and a staircase goes in. That is the whole job.
It is the cheapest way into a loft by a wide margin, typically £30,000 to £45,000 before VAT against £45,000 to £75,000 for a dormer. It is also the quickest, at six to eight weeks on site, and by far the least disruptive to the outside of the building. The trade-off is simple and unavoidable: it does not add any height or any floor area. It only makes usable what is already there.
In Cornwall it has a second advantage that matters enormously, and most people do not know about it. The permitted development class covering rooflights contains no restriction on article 2(3) land. Dormers lose their rights in conservation areas, National Landscapes and World Heritage Sites. Rooflights generally do not. In a county with 145 conservation areas and ten World Heritage Site areas, that is often the difference between starting in four weeks and starting in four months.
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.
Why a rooflight conversion is often the right answer
Less money, less time, less disruption, and far less argument with the planning system.
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£15,000 to £30,000 cheaper
No structural box built out from the roof, no flat roof system, no new cheeks to insulate to wall standard, and usually no planning application. The saving is not marginal - it is most of the price of a small car.
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It keeps permitted development rights
Class C of the permitted development order covers roof alterations and, unlike the dormer class, says nothing about article 2(3) land. So a rooflight conversion normally stays permitted development in a conservation area, in the National Landscape and inside the Mining World Heritage Site.
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Cornwall Council actively prefers them
Its own heritage guidance calls metal conservation rooflights ideal in a conservation area context, notes they are normally top hung so less visually disruptive than centre-pivot units, and in the same document warns against large box-like roof extensions.
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More daylight than a vertical window
A rooflight in the slope faces more sky than a wall window of the same size, so it delivers considerably more daylight. Two well-placed rooflights will make a loft room brighter than the bedroom below it.
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Six to eight weeks, and the roofline never changes
There is no scaffold-heavy structural stage and no period where the roof is open to the weather beyond the window openings themselves. From the street, most people never notice the work happened.
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It is reversible in a way a dormer is not
That matters on older Cornish buildings, and it is why the SPAB position on historic roofs is that the existing structure should not be damaged to accommodate either a dormer or a rooflight. A well-detailed rooflight is much the smaller intervention.
- 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
On the Cornish roofs we survey that already have 2.2 metres of head height, a rooflight conversion turns out to be the better-value option about seven times in ten.
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 Velux loft conversion company
Head height comes before everything else, because a rooflight conversion adds none at all, so the existing roof has to have it already. Measure from the top of the ceiling joists to the underside of the ridge. Around 2.2m and the job works comfortably, because the new floor and the new insulated ceiling both take a slice. Around 2m and it becomes marginal - possible, but you will be ducking in places, and a dormer over the stair may be the honest answer. If a company is quoting a rooflight conversion on a roof they have not measured, they are quoting for a room you may not be able to stand up in.
The next question is what the 150mm rule means for your particular roof. Class C permits roof alterations provided nothing protrudes more than 0.15 metres beyond the plane of the original slope. Standard centre-pivot rooflights are designed to sit within that. But it is measured from the original slope, so if you are also adding insulation over the rafters, or if the roof has been over-boarded at some point, the margin can disappear. On a listed building none of this applies anyway and you will need listed building consent, which at least carries no fee.
On a traditional Cornish slate roof there is a further question, about ventilation. It is the detail that gets missed most often and it is serious. Traditional scantle slating is laid in diminishing courses and bedded in lime mortar, which makes it a sealed system. SPAB's technical guidance for the south west is explicit: if any membrane or underlay is installed, or a ceiling is fixed to the rafters, the batten space must be ventilated - usually with eaves ventilators and a high-level vent at the slope or ridge. A loft conversion does exactly that to the roof. Get it wrong and you have created a condensation trap inside a hundred-year-old roof structure.
Rooflight conversion against a dormer
The honest comparison. A rooflight conversion is cheaper and easier, but it cannot do the one thing a dormer exists to do.
| Velux / rooflight | Dormer | |
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| Typical cost (ex VAT) | £30,000 - £45,000 | £45,000 - £75,000 |
| Adds head height | No | Yes, substantially |
| Adds floor area | No | Yes |
| Permitted development in a conservation area, National Landscape or the Mining WHS | Usually yes | No - full application needed |
| Time on site | 6 - 8 weeks | 8 - 10 weeks |
| Change to the roofline | None visible from most angles | Significant |
| Needs head height of | 2.2m or more already | Works from around 2m |
Conservation rooflights and where they matter
A standard rooflight has a chunky white plastic frame that sits proud of the slate. A conservation rooflight is a slimmer steel or aluminium unit with a central glazing bar, set much closer to the roof plane, in a matt dark finish. On a Cornish slate roof the difference is obvious from the ground, and inside a conservation area it is frequently the difference between an approval and a refusal.
Cornwall Council's guidance on common works to listed buildings puts it plainly: rooflights and flues must be discreet, low-profile and matte-finished. Its Camelford heritage roofing guidance goes further and describes conservation units as combining modern performance with traditional appearance, and points out they are usually top hung, so in use they are less visually disruptive than centre-pivot types. They cost more per unit, and on any building where the roof is seen they are worth it.
If your survey comes back saying the head height is not there, do not write the loft off. Read the dormer loft conversions page next, because a dormer positioned over the stair is usually what makes an unconvertible roof convertible.
Velux loft conversion costs in Cornwall
Guide ranges before VAT for a rooflight conversion in Cornwall.
- Rooflight conversion, single room
- £30,000 - £38,000
- Rooflight conversion with en-suite
- £38,000 - £45,000
- Standard rooflight, supplied and fitted
- £1,200 - £1,800 each
- Conservation rooflight, supplied and fitted
- £1,800 - £2,800 each
- Cornwall Council building control
- £1,140 inc VAT
No planning fee in most cases, which is the quiet saving. If you want certainty before you start, Cornwall Council will confirm in writing that your permitted development rights have not been removed for £200, or issue a formal Lawful Development Certificate for a proposed use at £274.
Velux loft conversion questions
- Is a Velux loft conversion permitted development in a conservation area?
- Usually yes, and this is the single most useful thing to know about them in Cornwall. Class B of the permitted development order, which covers dormers and other roof additions, is expressly unavailable on article 2(3) land - conservation areas, National Landscapes, World Heritage Sites. Class C, which covers other alterations to a roof including rooflights, contains no such restriction. So a rooflight conversion generally remains permitted development in all of those areas, subject to nothing protruding more than 150mm beyond the original roof slope and to any Article 4 direction or planning condition on your specific property. Listed buildings are the exception and need listed building consent, which is free to apply for.
- How many rooflights will I need?
- Enough to satisfy three separate requirements, which is usually two or three in a standard loft room. Daylight is the obvious one. Purge ventilation is the second - Approved Document F wants at least four air changes an hour direct to outside, and for a window opening 30 degrees or more that means an opening of at least one twentieth of the room's floor area. The third is escape: any new habitable room above ground level needs an escape window with a minimum unobstructed openable area of 0.33 square metres, at least 450mm high and 450mm wide, with the bottom of the opening no more than 1100mm above the floor. That last one drives the position more often than the daylight does.
- Is Velux the only brand?
- No. Velux is the name everyone uses the way people say Hoover, but Fakro, Keylite and Roto all make equivalent units, and for conservation work the slim metal-framed units from specialist manufacturers are a different product again. What matters is the U-value, which needs to be 2.2 W/m²K or better to satisfy Approved Document L for a new rooflight, the flashing kit being correct for your roof covering, and on a slate roof the flashing being suitable for a natural slate rather than a concrete tile. We specify per roof rather than per brand.
- Will rooflights leak?
- Not if the flashing kit matches the roof covering and it is installed to the manufacturer's detail. Almost every rooflight leak traces back to one of three things: the wrong flashing kit for the covering, an underlay that was cut and not properly dressed into the flashing, or a unit installed at a pitch outside its permitted range. Most units need a minimum roof pitch of around 15 degrees. On a traditional mortar-bedded Cornish slate roof there is an extra consideration, which is that you are cutting into a sealed system, so the batten space around and below the opening needs ventilating properly rather than just being closed up.
- Can I put a rooflight in the front of my roof?
- Under Class C, yes, in a way you could not with a dormer - the class does not have the principal elevation restriction that Class B has. It does require that any window in a side-facing roof slope is obscure-glazed and non-opening below 1.7m above floor level. In practice, on a front slope in a conservation area or the World Heritage Site, the sensible move is a conservation rooflight in a matt dark finish, which is what Cornwall Council's own guidance points people toward. A standard white plastic unit on a front slate slope is the thing that draws complaints, even where it is technically permitted.
- What if my head height is not quite enough?
- Then a rooflight conversion is the wrong product and you should be told so at the survey rather than sold one anyway. There is one useful allowance here: Approved Document K permits reduced headroom specifically over a loft conversion stair, 1.9m at the centre of the flight and 1.8m at the side, rather than the usual 2m. That rescues plenty of marginal roofs. But it applies to the stair, not to the room. If the room itself is short of height, the options are a dormer, a hip to gable if you have a hipped end, or raising the roof - and the last of those roughly doubles the cost and almost certainly needs planning permission.
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.