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Roof Lanterns: What, Why and How?

roof lanterns
(Image credit: Korniche)

Roof lanterns are a highly desirable feature in homes. A room topped with one of these glazed structures immediately exudes drama, feels light and bright and just a touch opulent. 

Our guide to roof lanterns is here to arm you with all the information you need in order to select, buy and install a roof lantern in your home — and there really is a design out there for every application. 

(MORE: Get a quote for your roof lantern)

What is a Roof Lantern?

Sometimes described as a conservatory in miniature, a roof lantern is a mainly glass structure that sits on a flat roof, bathing the room below in light.

roof lanterns

All the frameless aluminium roof lanterns from ID Systems are handmade meaning you can specify the correct size and configuration for your project.  (Image credit: ID Systems)

Are Roof Lanterns Different to Rooflights?

A rooflight is simply a window that is set in a non-vertical plane. In a pitched roof, it would be called a sloping rooflight: on a flat roof, it would be a flat rooflight or flat roof window

In contrast, a roof lantern is made up of a series of panes or windows, assembled to make a 3D structure. 

Roof lanterns were first used by the Victorians and therefore tend to be an architectural feature of older style properties, whilst flat rooflights are a more modern feature and are therefore stylistically neutral. 

As glazing and waterproofing techniques have evolved, it is now possible to have a 3D roof lantern with very little framing, meaning they are now being specified for more contemporary homes as well as traditional. 

roof lanterns

The beautiful range of roof lanterns from Just Roof Lantern offer designs made from both aluminium and timber as well as aluminium only.  (Image credit: Just Roof Lanterns)

Are Roof Lanterns More Expensive Than Rooflights?

There isn’t a great deal between them, though the flat rooflights tend to be simpler to make and therefore a little cheaper. In each case, there is a big premium for bespoke rooflights or lanterns, made individually to your own specifications.

roof lanterns

Combined with a set of sliding doors in this kitchen from Brayer Design, the roof lantern ensures that the new space is flooded with natural light.  (Image credit: Brayer Design)

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Is Planning Permission Required for a Roof Lantern?

A roof lantern may well require planning permission if it is being placed within an existing flat roof, as it must, by definition, be higher than any existing part of the roof it is set in — a key determinant of the need for planning permission. 

If however, you are installing roof lantern as part of a new build or when building an extension, then it’s not going to require any additional permission. The guidelines are quite complex and you would do well to look at the Planning Portal (England or Wales) guidance on whether your project requires planning permission. Alternatively, check with your local planning department to see if they can clear things up.

roof lanterns

Unlike rooflights, roof lanterns may well require you to apply for planning permission — if in any doubt check with your local planning department. This striking design is from Just Roof Lanterns(Image credit: Just Roof Lanterns)

Roof Lanterns and the Building Regulations 

If your roof lantern forms part of a new extension or a new house, then the building regulations should be dealt with as part of the larger job. 

However, if you wish to install a roof lantern in an existing roof, you will need to have it passed and inspected by building control. It is important that the roof lantern opening is structurally sound, as the roof joists are likely to have to be re-arranged. The roof lantern and its opening will have to meet the current requirements for thermal efficiency. It is certain that the roof lantern would have to be double glazed at the very least.

roof lanterns

Roof lanterns from Thames Valley Window Company are made from aluminium and feature Active Neutral Glass which helps to regulate the temperature in the room and is also self-cleaning.  (Image credit: Thames Valley Roofing Co.)

What Issues Occur with Roof Lanterns?

Check the glazing characteristics. Just like conservatories, spaces with roof lanterns risk getting too hot in summer and too cold in winter. Consider triple glazing for winter heat retention and low-g glass for summer coolth. You can have both — i.e. low-g triple glazing — but it costs about 50% more than regular double glazing.

Look out for roof lanterns that have an opening vent. This could be useful in summer, when it gets very hot. However, this will require automatic opening, which will add a lot to the price. 

How are Roof Lanterns Installed? 

roof lanterns

A great example of just how transformative a roof lantern can be in a new space. This aluminium/timber composite design is from Aliwood Roof Lanterns(Image credit: Aliwood Roof Lanterns)

In a new roof, the opening will formed by the carpenters during the carcassing process. Details of the sizing and any upstands required should be available from the manufacturers, together with advice on insulating the sides of the opening to avoid cold bridging and condensation. 

Often there is a delay between the roof being formed and the roof lantern appearing onsite, so a temporary cover needs to be put in place: corrugated plastic sheets are handy here. The roof covering material is installed over the upstand, before the roof window itself, so that the final waterproofing takes place when the window flashings are fitted onto the upstands.  

This work needs to be supervised by a building inspector: the alternative route to window compliance, using a FENSA registered contractor, does not cover new window installations, only replacements.

Where Should my Roof Lantern be Positioned? 

The usual place to install an overhead rooflight is in a kitchen, where good quality day lighting is best appreciated. Popular spots include above dining tables and over islands or peninsulas in large kitchens. Generally, it makes sense to keep any overhead lighting fairly central, unless there is a specific reason to locate it to one side. 

roof lanterns

Consider where a pool of natural light could be most beneficial and locate your roof lantern accordingly. This frameless design from ID Systems ensures this open plan space is well lit.  (Image credit: ID Systems)

Are Roof Lanterns Hard to Clean?

Flat roofs are usually accessible from the ground via a ladder or from a window and generally flat roofs provide a safe working platform. External cleaning and maintenance is therefore fairly easy to achieve, as they simply require an occasional wash and window cleaners are well used to them. 

Internally, access can be more challenging and may require a step-ladder. On the other hand, there isn’t very much to make the internal glass dirty and cleaning is needed only very occasionally. 

roof lanterns

This aluminium roof lantern from Keylite features self-cleaning glass.  (Image credit: Keylite)

How Much do Roof Lanterns Cost?

The cost of roof lanterns very much depends on their size and configuration, material, glazing specification and any additional extras you choose to have (such as solar control measures and automated opening mechanisms). 

A small, basic, roof only (i.e.no side windows) PVCu roof lantern might start from £700 uninstalled, but this price will rise quickly with the addition of non-white colours, easy-clean glass, fittings and the like. Small timber and aluminium roof lanterns start from approximately £1,100. 

However, these prices lie at the lower end of what people usually end up paying and do not include any extras or installation — which will easily add £1,500 - £2,500. 

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