Choosing answer
Roof lantern or flat rooflight: which is better for your extension?
Neither is better in every house. The two give light of a different kind, stand at different heights over the roof and meet the planning rules differently, so the choice comes down to the room and the roof.
The answer
Pick a lantern when you want a feature that lifts the ceiling and brings light in from several sides, and the roof can carry the weight. Pick a flat rooflight when you want a low, clean profile, a smaller footprint or a simpler planning route. A flat rooflight sits close to the roof, so on a house it has a better chance of staying within the 150mm limit.
How does the light differ?
A lantern lets daylight in through sloping sides as well as the top, so it moves across the room through the day. A flat rooflight lights what is straight below it more directly.
A flat rooflight is one sheet of glazing set into the roof, and its light falls mainly downward in a pool under it. The pool is bright at midday and thin early and late.
What the lantern adds
A lantern has faces at several angles, so it catches low morning and evening light from the side as well as light from overhead. The inside of its kerb and the room's ceiling around it act as a soft reflector, spreading the glow. The space underneath tends to look taller, because the ceiling visibly opens upward.
Choosing for the use
For a dining table or kitchen island, a flat rooflight directly above gives good task light. For a long, dim family room where you want an even glow and a sense of height, a lantern is the more natural fit. Both lose some light to the frame, and slim frames reduce that loss, as our guide to frame materials explains.
How much headroom and roof height does each need?
A lantern needs a kerb plus its own sloping glass, so it rises well above the roof and wants ceiling height to appear inside. A flat rooflight sits close to the roof surface.
Height is the plainest difference between the two. A flat rooflight is glass in a low upstand, often set at the height manufacturers recommend to keep water off the frame, commonly around 150mm above the finished roof. A lantern stands on a kerb of its own and then climbs to a ridge or peak, so its total height is much greater.
What that does indoors
Inside, the lantern's lining reveals a shaft of space above the ceiling line. That works well where the extension ceiling is generous. If the room is already low, the shaft adds drama, but the lantern is more visible from the garden as a box on the roof.
What it does outside
From the garden and from neighbouring windows, a lantern is a visible object. A flat rooflight is nearly invisible from the ground. If an upstairs window looks down onto the roof, think about what its occupants will see, because a flat rooflight presents a calm sheet of glass while a lantern presents a form. The question of sightlines is part of why flat roof rooflights suit some upper-floor views better.
Which one is easier on planning permission?
On a house, a low flat rooflight can fit within the 150mm Class C limit while a lantern often exceeds it. On any flat or maisonette, both need planning permission.
On a house in England, a rooflight is permitted development under Class C if it projects no more than 150mm beyond the plane of the roof slope and sits no higher than the highest part of the roof. A flat rooflight on a low upstand can approach that, though the upstand itself can use up the allowance. A lantern's kerb and glass together usually pass it, which means an application.
Flats and Tyneside flats
Flats and maisonettes have no householder permitted development. A new flat rooflight or a new lantern on an upstairs or downstairs Tyneside flat both need planning permission from the council. The roof may be owned or shared in a way your title or lease describes, so read that first and raise it with whoever owns the other flat.
Other things that change the picture
An Article 4 direction or a condition on an earlier permission can remove Class C from a house. A listed house keeps Class C on the planning side, but almost any rooflight on it needs listed building consent. Our fuller answer on lantern planning permission covers each case.
| Point | Roof lantern | Flat rooflight |
|---|---|---|
| Light | From several faces, shifting through the day | Direct from above, in a pool below |
| Height over roof | Kerb plus sloping glass | Low upstand, close to the roof |
| Look from garden | A visible form | Almost flat to the roof |
| Planning on a house | Often over 150mm, so an application | Can stay within 150mm if the upstand is low |
| Roof load | Heavier, concentrated at the kerb | Lighter |
How do I decide between them?
Start with the roof's capacity and the planning route, then the ceiling height, the view from upstairs and the look you want. We talk the options through at a free survey.
Work through four questions in turn. Can the roof carry a lantern? If not, the choice is made. What does the planning route look like for your home? If you live in a flat, both need permission, so it becomes a design choice. How high is the ceiling, and does anyone look down on the roof from an upper window? Finally, what look do you want, a feature or a quiet sheet of glass?
Combining the two
Some extensions use both: a lantern over the dining end and a flat rooflight over the cooking end, or a pair of flat rooflights where a single lantern would be too much. We talk this over at the free survey, and the written quote afterwards does not move. Our roof lantern service page shows how the job runs.
Last doubts about lanterns and flat glass
Is a lantern always more expensive than a flat rooflight?
Not as a rule, because size, glazing, frame and roof work all matter. We publish no figures. Our costs page covers what drives a quote, minus any figures.
Does a lantern make a room hotter in summer?
Any large glazed area can add heat, and a lantern has a lot of glass facing different directions. Solar control glazing and opening vents reduce this. The same choices apply to a flat rooflight of similar glazed area.
Can I change my mind after the survey?
Yes. The visit costs nothing and precedes pricing, so the choice between a lantern and a flat rooflight can still move once you have seen the options in your own roof. The fixed quote is written after that.
Which one suits a Tyneside flat's back kitchen?
Either, once permission is in place. The low profile of a flat rooflight can suit a small offshoot, while a lantern suits a larger, higher kitchen. Start with the planning route in our house-first guide.