If you are renovating or extending and want more natural light from above, the choice usually comes down to two options: a rooflight or a roof lantern. Both work, and both look good, but they suit different rooms, roofs and budgets, and choosing the wrong one is a common and avoidable mistake.
This guide compares rooflights and roof lanterns on the things that actually decide it: real prices, thermal performance, light, planning and installation. It ends with a clear steer on which suits which project, and because we supply both, that steer is not weighted towards selling you one over the other.
Where the evidence points one way, we say so. A flat rooflight is usually the better buy for value and insulation, while a roof lantern earns its extra cost where impact and even light matter most. The rest of this guide explains why, so you can match the right one to your space.
Rooflight, skylight or roof lantern: what’s the difference?
First, the terms. Rooflight and skylight mean the same thing in everyday use: a glazed unit set into a roof to bring in daylight. Some suppliers reserve roof window for pitched-roof units like a Velux, but for a flat roof, rooflight and skylight are interchangeable. Our guide to the difference between skylights, rooflights and roof windows covers the terminology in full.
A roof lantern is different. It is a raised, multi-paned structure that sits above the roofline, with sloped sides rising to a central ridge. So the real comparison here is between a flat glazed unit that sits low in the roof, and a raised, three-dimensional feature that stands proud of it. For more on the range, see our flat roof skylights buying guide, and our Roof Lanterns Complete Guide goes deeper on lanterns specifically.
Rooflights vs roof lanterns at a glance
Here is how the two compare on the decisions that matter. The sections below explain each in more detail.
| Factor | Flat rooflight | Roof lantern |
|---|---|---|
| Profile | Low, sits close to flush | Raised feature above the roofline |
| Roof type | Flat and low-pitch roofs (up to about 15°) | Flat and low-pitch roofs (up to about 15°) |
| Price range (ex VAT) | From £259 (to around £2,800 for most domestic sizes) | From £449.45 (Wendland) to £4,247.01 (large Korniche) |
| Light | Direct, shifts with the sun | From several angles, more even across the room |
| Thermal performance | Often better; fewer glazed joints, triple glazing reaches 0.9 W/m²K | More glazed joints, so typically a higher whole-unit U-value |
| Ventilation | Opening versions available | Usually fixed, openers available on some |
| Planning | Simplest; flush units are usually permitted development | Raised profile can exceed the 150mm limit, so less clear-cut |
| Best suited to | Value, smaller or single spaces, a low profile, conservation areas | Larger open-plan rooms, a statement feature, period homes |
The differences that actually affect your decision
Cost
On price, the flat rooflight wins clearly. Our flat rooflight starts from £259 ex VAT, and because it drops into a simpler upstand with less structural work, it also costs less to install. Roof lanterns start higher: our PVCu Wendland from £449.45 ex VAT, rising to £4,247.01 for a large aluminium Korniche. A lantern’s size, weight and larger opening also make it the more involved fit.
What moves the price on either product is much the same: size, glazing specification, frame material and whether it opens. For a full breakdown including installation, see our rooflight and skylight cost guide. It is also worth knowing what separates a well-made rooflight from a cheap import before choosing on price alone: our director explains the hidden cost of cheap rooflights.
Light and glare
This is where the lantern earns its place. Its sloped, multi-paned shape admits light from several directions at once, spreading daylight more evenly across a room and into its corners. A flat rooflight gives a strong, direct pool of light that shifts across the room as the sun moves, which is bright and effective but less even.
Glare follows the same logic. Direct sun strikes the whole surface of a flat rooflight at once, so glare lasts until the sun moves on. A lantern’s angled panes are only caught one at a time, so any glare is limited to a single pane. For a larger open-plan room where you want soft, even light, the lantern is the stronger choice.
Thermal performance
Here the flat rooflight tends to win, and it is the point many comparisons skip. A roof lantern is made of several panes joined together, and every joint between panes is a route for heat to escape. A flat rooflight has far fewer joints, essentially one sealed unit meeting the upstand, so for a comparable specification its whole-unit U-value is usually lower.
The gap widens with triple glazing. Our triple-glazed self-clean rooflight reaches a U-value of 0.9 W/m²K, better than a typical lantern. So if keeping heat in and bills down is high on your list, a well-specified flat rooflight is often the better performer. Our guide on whether rooflights are energy efficient goes into this further.
Profile and kerb appeal
A flat rooflight sits low and barely changes the outline of your roof, which keeps it discreet and makes it the easier choice in a conservation area. A roof lantern is the opposite: a deliberate, raised feature that stands proud of the roof and is visible from outside. Neither is better here, it depends on whether you want the roof to make a statement or stay quiet. A lantern suits a period property or an extension where you want a focal point, while a rooflight suits a modern, minimal look.
Roof type and installation
Roof type sets the outer limits for both. A flat rooflight is built for flat and low-pitch roofs, from a minimum fall of about 5 degrees for drainage up to around 15 degrees, and a roof lantern suits the same range. For a genuinely pitched, tiled roof, neither is the standard answer: that calls for a pitched roof window, fitted flush within the slope and rated for pitches up to 90 degrees, which we cover in our flat versus pitched skylight guide. If your roof sits near the 15-degree boundary, it is worth checking the specific product, since a few units carry wider pitch tolerances.
Both a flat rooflight and a lantern fit onto a builder’s upstand and can be installed by a competent builder or roofer. The difference is scale: a lantern is heavier and larger, so bigger spans usually need the roof structure assessed. If you are working with a flat roof, our guide on installing a rooflight on a flat roof is a useful next read.
Ventilation
If you want airflow as well as light, a rooflight has the edge on availability. Opening versions, both manual and electric, are readily available: see our electric and manual opening rooflights. Most roof lanterns are fixed, though some, including the Wendland, can be quoted with an opening module. For a kitchen or bathroom where clearing steam matters, an opening rooflight or a lantern with an opener is worth specifying from the start.
Planning permission
Most roof glazing in England and Wales is covered by permitted development, so planning permission is not usually needed. A flush flat rooflight almost always qualifies, provided it projects no more than 150mm above the roof and sits below the highest point of the roof, with obscure glazing on any side elevation.
A roof lantern is less clear-cut. Because it is a raised structure, it can project more than that 150mm limit, so its permitted development status depends on the installation and is worth confirming with your local planning authority. Listed buildings, conservation areas and properties with an Article 4 direction are the main exceptions either way. The conditions are set out on the Planning Portal and in the GOV.UK technical guidance, and our own planning and building regulations guide covers the detail.
Which should you choose?
On balance, a flat rooflight is the right call for most homeowners, and a roof lantern is worth the premium in specific cases. Here is the short version.
Choose a flat rooflight if:
- Value matters and you want the lower price to buy and install
- The room is smaller, or a single space where even light is not critical
- Thermal performance is a priority, since a triple-glazed unit reaches 0.9 W/m²K
- You want the simplest fit and the most straightforward planning route
- You want a discreet profile, or you are in a conservation area
Choose a roof lantern if:
- The room is large or open-plan and you want soft, even light throughout
- You want a genuine architectural feature that stands out inside and out
- You have a flat roof and the budget for a statement piece
- You are working on a period or traditional property where a lantern suits the style
If you are torn, start with the flat rooflight. It is cheaper, insulates better and fits more roofs, so the lantern needs a clear reason, such as impact or a large room that needs even light, to justify the extra.
Our rooflights and roof lanterns
If you have decided, or you want to see what real products cost, here are two on each side, from value to premium.
TGS Flat Rooflight
Our Flat Rooflight is a bespoke, low-profile glazed unit for flat and low-pitch roofs. Double glazed it reaches a U-value of 1.1 W/m²K, and triple glazed 0.9. From £259 to £2,800 ex VAT depending on size and glazing.
Triple-Glazed Self-Clean Rooflight
The Triple-Glazed Self-Clean Rooflight reaches 0.9 W/m²K, the lowest U-value in our range, with self-cleaning glass as standard and a 20-year warranty. From £163 to £619 ex VAT, with a fast 1 to 3 working day lead time.
Wendland Roof Lantern
The PVCu Wendland is the lowest-priced of our lanterns, with a 20 degree pitch, a U-value of 1.2 (1.0 on upgraded glass) and optional solar-control glass for south-facing rooms. From £449.45 to £2,009.28 ex VAT, with a 10-year warranty.
Korniche Roof Lantern
The aluminium Korniche is the premium option, with slim sightlines, self-cleaning glass as standard, a 25 degree pitch and spans up to around 6m x 4m. U-value 1.0 to 1.2. From £694.56 to £4,247.01 ex VAT, with a 10-year warranty.
Why buy from Toughened Glass Systems
We supply both rooflights and roof lanterns, across our own flat rooflight range and named lantern brands (Korniche, Wendland and Brett Martin), so whichever suits your project, you can buy it in one place. Every product page lists real prices, U-values, warranties and lead times, not a single figure blended across the range. We also offer a Best Price Guarantee on like-for-like products and UK-wide delivery, backed by years of trading and a strong review history.
Browse our full rooflights and skylights range, including roof lanterns, flat roof skylights and opening rooflights, or learn more about us and contact our team for advice on your project.
Related guides
- Roof Lanterns Complete Guide
- What Is the Difference Between Skylights, Rooflights and Roof Windows?
- Best Skylights for Flat Roofs
- The Hidden Cost of Cheap Rooflights
- Best Velux Window Alternatives
- Rooflight and Skylight Cost Guide
- Are Rooflights Energy Efficient?
- Can You Install a Rooflight on a Flat Roof?
- 14 Ways to Increase Natural Light in a Room
- Velux vs Fakro: Which Roof Window Is Right for You?
Frequently asked questions
Are rooflights cheaper than roof lanterns?
Yes, generally. A flat rooflight starts from £259 ex VAT against £449.45 for our cheapest lantern, and it costs less to install because it needs less structural work. Lanterns cost more to buy and fit, which is part of what you pay for the raised, feature design.
Which lets in more light, a rooflight or a roof lantern?
A roof lantern spreads light more evenly, because its sloped panes admit daylight from several directions and reach further into a room. A flat rooflight gives strong, direct light that moves across the room with the sun. For a large open-plan space, the lantern usually feels brighter and more even.
Which is more energy efficient?
A flat rooflight often insulates better. Its simpler construction has fewer sealed joints than a multi-pane lantern, so less heat finds a way out, and a triple-glazed version reaches 0.9 W/m²K. A lantern can still be well insulated, but for the lowest heat loss the flat unit has the edge.
Can you put a roof lantern on a pitched roof?
No. Roof lanterns are designed for flat and low-pitch roofs, up to about 15 degrees, not steeper pitched ones. If your roof is genuinely pitched, the right product is usually a pitched roof window, the in-plane Velux or Fakro type fitted flush within the slope, rather than a flat rooflight, which suits the same flat and low-pitch range. If you are comparing pitched roof windows, our Velux alternatives guide weighs up the options.
Do rooflights or roof lanterns need planning permission?
Usually neither, under permitted development. A flush rooflight almost always qualifies. A raised lantern can exceed the 150mm projection limit, so it is more likely to need checking with your local planning authority. Listed buildings, conservation areas and Article 4 properties are the main exceptions.
Which is better for a kitchen extension?
It depends on the size and what you want. For a large open-plan kitchen-diner where you want even light and a feature, a lantern works well. For a smaller or budget-conscious extension, or where you want ventilation, an opening flat rooflight is often the better fit.
Is a roof lantern worth the extra cost?
It is if you want the architectural impact and the even, multi-angle light it gives a larger room. If your priority is value and thermal performance, a flat rooflight delivers more for less, so the lantern is worth it mainly where its looks and light genuinely matter to the space.