Written by the Glazing Store team: we're an online supplier of Korniche, Atlas, Sheerline and Solaris roof lanterns, bi-fold doors and rooflights, and we take sizing and glass questions from homeowners and builders on 01604 347222 every working day. Last updated: 6 November 2026
TL;DR: A roof lantern is a raised glass roof that sits on a timber kerb on a flat roof. Light comes in from the top and the sides, so it lights a room better than a flat rooflight of the same footprint. Choosing one comes down to five decisions, in this order. Size: order to the external kerb size, and aim for glass covering 15–20% of the floor. Glass: clear for north-facing rooms, tinted or premium for south-facing ones. Brand: Korniche for value and self-assembly, Atlas for solar control, Sheerline S1 for security, Solaris for the lowest price on small sizes. Rules: a new extension's lantern goes through its Building Regulations application, and rooflights must meet 2.2 W/m²K under Part L. Budget: a 1500 x 2000mm Korniche is £1,237.68 inc VAT supply-only.
Contents
- What is a roof lantern, and how is it different from a rooflight?
- Which roof lantern brand should I choose?
- Which glass should I choose?
- What size roof lantern do I need?
- How much does a roof lantern cost?
- Do I need planning permission or Building Regulations approval?
- Where does a roof lantern work best?
- Should I pair a roof lantern with bi-fold or sliding doors?
- What should I check before I order?
- FAQs
What is a roof lantern, and how is it different from a rooflight?
A roof lantern is a pitched glass roof, usually 20–25°, made of aluminium rafters and sealed glass units. It sits on a raised kerb (upstand) on a flat roof. Because it rises above the roof, daylight enters through the sloping sides as well as the top. That's why a lantern makes a room feel taller and brighter than a flat rooflight with the same base size. It also turns the ceiling into a feature, which a flat rooflight doesn't.
| Roof lantern | Flat glass rooflight | Pitched-roof skylight (loft window) | |
|---|---|---|---|
| Where it goes | Flat roof, on a raised kerb | Flat roof, on a kerb, glass almost level | Sloping roof, in line with the tiles |
| Light | From the top and four sides | Straight down | Angled, from one direction |
| Look from inside | A glazed "room" in the ceiling | A clean glass panel | A window in the slope |
| Rain run-off | Pitched glass sheds water and dirt | Needs a slight fall; more prone to standing water marks | Sheds water with the roof |
| Typical use | Kitchen extensions, orangeries, open-plan rooms | Narrow spaces, corridors, contemporary minimal ceilings | Loft conversions |
If you're unsure which suits your roof, our skylights vs roof lanterns comparison goes deeper, and you can browse both on our rooflights page.
Which roof lantern brand should I choose?
We sell four aluminium lantern systems. They're all good. They're built for slightly different jobs, so the best choice depends on what matters most to you. Prices below are our live supply-only prices inc VAT, checked 6 November 2026.
| System | 1000 x 1000mm | 1500 x 2000mm | Largest stock size | Best for |
|---|---|---|---|---|
| Korniche (Clear 1.2) | £738.92 | £1,237.68 | 3000 x 5000mm (£3,968.89) | Best value, quick self-assembly, six glass choices |
| Atlas (self-clean solar blue) | £1,015.28 | £1,555.39 | 1500 x 3000mm (£1,980.20) | South-facing rooms: Atlas glass reflects up to 60% of solar heat |
| Sheerline S1 | £993.60 | £1,686.00 | 2000 x 4000mm (£3,360.00) | Security: anti-tamper screws and enclosed glazing |
| Solaris | £589.04 | £1,239.05 | — | Lowest price on small lanterns; strong ridge, 20° pitch |
Our honest view: for most self-build and builder-fitted extensions we point people to Korniche first. Made for Trade publishes a 3m x 1.5m Korniche going together in under 30 minutes, with no cutting or silicone inside the structure. It also has the widest size range we sell. Korniche's lantern won a King's Award for Enterprise in Innovation in 2024. Choose Sheerline S1 if the lantern sits over a roof a burglar could reach, or Atlas if overheating worries you more than price.
Which glass should I choose?
Glass makes more difference to how the room feels than the frame does. Korniche publishes how much of the sun's heat each glass type reflects and how much daylight it lets through:
| Korniche glass | Heat reflected | Light through | U-value (W/m²K) | Choose it for |
|---|---|---|---|---|
| Clear 1.2 | 31% | 77% | 1.2 | North- or east-facing rooms where you want maximum light |
| Neutral 1.2 | 59% | 44% | 1.2 | West-facing rooms; cuts heat without a blue tint |
| Blue 1.2 | 73% | 32% | 1.2 | South-facing kitchens on a budget |
| Premium Clear 1.0 | 38% | 70% | 1.0 | Bright rooms used all year where winter warmth matters |
| Premium Aqua 1.0 | 82% | 28% | 1.0 | South-facing rooms that overheat in summer |
| Premium Blue 1.0 | 83% | 23% | 1.0 | The most heat control of the range |
The trade-off is simple: the more heat a glass reflects, the less light it lets in. Lower U-values mean less heat escapes in winter. Building Regulations (Approved Document L) set a limit of 2.2 W/m²K for new rooflights, so every option above beats it comfortably. If you want the full detail on U-values and what they mean for heating bills, read our glazing U-value guide.
What size roof lantern do I need?
Two rules cover most rooms:
- Order to the external size of the finished kerb. Don't order to the hole in the ceiling or the internal kerb measurement. The lantern's base frame drops over the outside of the kerb like a lid on a box.
- Aim for glass covering about 15–20% of the floor area, and leave at least 500mm of flat roof on every side for falls and drainage.
| Extension size | Floor area | Typical Korniche size | Price (Clear 1.2, inc VAT) |
|---|---|---|---|
| 3 x 3m | 9m² | 1000 x 1500mm | £923.24 |
| 4 x 3m | 12m² | 1500 x 2000mm | £1,237.68 |
| 5 x 3m | 15m² | 1500 x 2500mm | £1,389.32 |
| 6 x 4m | 24m² | 2000 x 3000mm | £1,770.71 |
Our roof lantern size guide covers how to measure the kerb, one large lantern versus two, ridge height and glass weight. For handling, see how heavy is a roof lantern.
How much does a roof lantern cost?
Supply-only, a Korniche roof lantern costs £662.28 to £4,346.70 inc VAT depending on size and glass. Going from standard Clear 1.2 to Premium Clear 1.0 glass adds roughly 5–10%. At 1000 x 2000mm, that's £1,048.72 vs £1,105.88. Bigger lanterns cost more in total but less per square metre, so one larger lantern is usually cheaper than two small ones covering the same area.
Your total project cost also includes:
- The kerb: timber upstand, insulation and plasterboard reveal.
- Roof finishing: the roofer dresses the membrane up the kerb.
- Fitting labour: a lantern takes a competent pair of hands a few hours once the kerb is built.
- Structural work: if joists need trimming for a wide opening.
Our Korniche roof lantern price guide breaks down every size, and if your opening isn't a stock size you can request a bespoke Korniche quote.
Do I need planning permission or Building Regulations approval?
Planning permission: a lantern on a new single-storey rear extension is normally assessed as part of that extension. If the extension falls within permitted development, the lantern usually does too, as long as the extension stays within the height limits. Adding a lantern to an existing roof is a roof alteration. The rules there are tighter, and conservation areas and listed buildings always need checking with your council first. The Planning Portal's extensions guidance is the place to start. Our planning rules article covers the common cases.
Building Regulations are separate from planning and always apply:
- Energy efficiency: rooflights must meet the 2.2 W/m²K limit in Approved Document L.
- Structure: wide openings or cut joists need checking under Approved Document A.
For a new extension, both are covered by the extension's own application. For a retrofit into an existing roof, use a building notice or full plans application.
Tip: put the lantern's exact external size and ridge height on your drawings before you submit them. Changing the size after approval can mean resubmitting.
Where does a roof lantern work best?
- Kitchen extensions: centre the lantern over the island or dining table. That's where you want the most light, and it makes the lantern the room's focal point. Our kitchen lighting article has more layout ideas.
- Orangeries: a large lantern within a solid perimeter roof gives the feel of a conservatory with year-round comfort. See our orangery roof lanterns guide.
- Open-plan living: in long rooms, a lantern over the darkest middle zone, away from the windows, makes the biggest difference.
- Garden rooms and home offices: pick a tinted or premium glass to control glare on screens.
Frame colour matters too. Anthracite grey and black externals suit most modern brickwork, and a white internal frame reads lighter against a white ceiling. Korniche can also be made in bespoke RAL colours.
Should I pair a roof lantern with bi-fold or sliding doors?
If you're building an extension, the lantern and the rear doors are your two biggest areas of glass. Plan them together so the frame colours match and the room gets light from two directions.
- Bi-fold doors open the whole width onto the garden. They're best if you want an indoor-outdoor room in summer. See our bi-fold door combinations guide and our bi-fold doors range.
- Sliding doors have bigger glass panes and slimmer frames, so you get more view when they're closed. See our Cortizo sliding door range and sliding patio doors.
For costs, read our bi-fold and patio door budgeting guide.
What should I check before I order?
Pre-order checklist 1. External kerb size measured and written down, length x width. 2. Kerb built square, level and to the planned height (commonly 150mm above the finished roof). 3. Glass chosen for the room's orientation. 4. Internal and external frame colours agreed. 5. Structure checked if the opening is wider than about 2000mm. 6. Two people (or lifting gear for big sizes) booked for delivery and fitting day. 7. Roofer booked to dress the membrane up the kerb.
Once it's in, our roof lantern maintenance guide covers cleaning, and will my roof lantern be noisy in the rain? answers the question everyone asks. Fitting it yourself? Start with our beginner's guide to installing a Korniche roof lantern.
FAQs
What is the difference between a roof lantern and a skylight?
A roof lantern is a raised, pitched glass structure on a flat roof that lets light in from the top and four sides. A skylight or flat rooflight sits almost level with the roof and lets light straight down. Lanterns give more light and a feature ceiling; flat rooflights are lower-profile.
Which roof lantern is best for a south-facing extension?
Choose a glass that reflects more of the sun's heat. Korniche Premium Aqua 1.0 reflects 82% and Premium Blue 1.0 reflects 83%, or choose Atlas self-clean solar blue glass. Clear glass lets in the most light but can make a south-facing room hot in summer.
How much does a roof lantern cost in the UK?
Supply-only, a Korniche roof lantern costs £662.28 to £4,346.70 inc VAT depending on size and glass. A 1500 x 2000mm lantern in Clear 1.2 glass is £1,237.68. Add the kerb, roofing and fitting labour for the total project cost.
What size roof lantern do I need?
Order to the external size of the finished kerb, and aim for glass covering about 15–20% of the floor area with at least 500mm of flat roof on every side. A 4 x 3m extension typically suits a 1500 x 2000mm lantern.
Do roof lanterns need planning permission?
A lantern on a new extension is usually treated as part of that extension, so if the extension is permitted development the lantern normally is too. Adding one to an existing roof, or working in a conservation area or on a listed building, needs checking with your council.
Are roof lanterns energy efficient?
Yes. Korniche glass units have U-values of 1.2 W/m²K (standard) or 1.0 W/m²K (premium), both well below the 2.2 W/m²K limit for rooflights in Approved Document L. Tinted glasses also cut summer heat gain.
Can I fit a roof lantern myself?
A competent DIYer with a helper can fit a Korniche lantern once a square, level kerb is built. Made for Trade says a 3m x 1.5m Korniche can be assembled in under 30 minutes. Large sizes need extra hands or lifting gear for the glass.
What is the best roof lantern brand?
It depends on the job. Korniche for value, range and easy self-assembly; Atlas for solar control; Sheerline S1 for security; Solaris for the lowest price on small sizes. We stock all four and can advise on 01604 347222.
Share:
How Heavy Is a Roof Lantern? What You Need to Know
Transform Your Space: The Benefits of Korniche Internal Glass Partitions in Home Design