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What is the Difference Between Rooflights or Skylights?

10 April 2020
Architecturally beautiful rooflights and skylights, designed to maximise the amount of light filtering into any property. With around 165 different skylight combinations to choose from, Sunsquare works with self-builders, architects and high-end residential, commercial and public firms to transform living and working areas.

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Skylights and rooflights

Skylights & Rooflights

If you’re confused about the various terms ‘roof light,’ ‘skylight’ or ‘roof window’, and what is best in your case, then don’t worry. You wouldn’t be the first person to be confused by it. The fact is, there is little or no difference between the meanings of the different terms. It has just happened that, over time, these different terms have become popular alternatives for what is essentially the same thing.

On this website, you will see these different terms cropping up frequently. This is because different people use different terms such us flat glass rooflights, roof lights windows or skylights rooflights to search when, really, they are searching for the same thing. Whether you call it rooflights, skylights, opening skylights or non opening skylights, the aim remains the same: maximise the natural light levels (and in the cases of non-fixed models – ventilation too) coming into a room or living space. Here at Sunsquare, we specialise in skylights and rooflights for flat roofs. Hopefully, this clarification helps you with your decision. If you want to talk through the various options and models with an expert advisor, please contact us.

Uncovering the nuances between roof lights and skylights

In recent years, it may have been prudent to say that there is little or no difference between rooflights and skylights. Nevertheless, as the industry has evolved, at the time of writing in 2017, there are increasing nuances between the capabilities and uses of rooflights and skylights. Throughout the remainder of this article we will uncover those distinctions to help put you firmly in the picture.

What is a roof window?

Roof windows remain a popular feature in the eyes of homeowners. They tend to come in standardised sizes and specifications and their ‘off-the-shelf’ appeal is certainly recognised by those who don’t require a bespoke design that’s made to order for their home. Rooflight windows must be CE marked prior to sale, meaning manufacturers must be able to declare to customers how their units perform under rigorous test conditions. Roof windows are also included under British Standards regulations (BS EN 14351 – 1:2010) which states they must be fitted in the same orientation and in plane with the surrounding roof, normally at a minimum pitch of 15-degrees.

What is a rooflight?

Rooflights now tend to refer to products fitted within a flat roof, or installed on a pitched roof that’s positioned out of plane with the level of the tiling i.e. standing out from the roof line more so than a skylight or roof window would. Another key difference between a roof light and a skylight window is that the former can be installed within listed buildings where new window openings in walls are not permissible. That’s because rooflights do not need to alter the external aesthetics of a building in order to provide abundant levels of natural daylight to the interior.

Rooflights are also commonly installed onto an upstand or kerb system, creating enough height to ensure water run-off when fitted on flat roofs.

What is a skylight?

Today, skylights refer commonly to products which are installed on traditional pitched roofs, as well as larger bespoke glazed units designed to be fitted on flat roofs and terraces, such as glass box extensions. The skylights installed onto flat roofs are very different to those fitted onto pitched roofs. They are capable of being fitted with electric motors for opening to offer much needed ventilation to interiors as well as roof access in some instances.

Example types of skylight

Customers are really spoiled for choice regarding types of skylight. There is a high degree of customisation on offer, with the flexible design of skylights – able to be manufactured to very specific requirements – providing a big advantage in the amount of viable applications available.

Skylights can be manufactured according to the goals of your project, or to the nature of the installation space. Suitable models are available for walk-on flat roofs, or in lantern shape, or even domed and more elaborate configurations. In both residential and commercial properties, the potential options are honestly endless: from fixed units providing wide external views to smaller models with remote opening capability. You can read our blog on types of skylight for more detailed information.


As well as offering a range of shapes and sizes to choose from, skylights or rooflights can be constructed with different materials which affect their performance.


Generally, a skylight’s glazing is made of either plastic or glass – usually selected depending on a few potential factors, such as your local climate or budget. Plastic is less expensive, and used frequently in specially-shaped skylights, trading some of its long-term aesthetics for durability (being susceptible to scratching and discolouring over time).

Glass is more expensive, with longer lasting performance in terms of visual appeal, and available in a huge range of styles. Glass in skylights may be made from tempered or laminated glass to low-emissivity coatings or self-cleaning glass. Each optional extra offers a unique benefit, sometimes being combined into a final skylight product in order to meet extremely high energy and safety standards.


Choosing between frame materials – either PVC, timber or aluminium – is also a matter of choice, with relative pros and cons for each type depending on the particulars of your property.

Metal frames such as aluminium are increasingly popular, providing great aesthetics to period properties as well as contemporary houses with their tailorable thin framework. Timber is also a classic favourite among homeowners due to the unique wooden look provided, while the availability of timber-aluminium composites provide the best of both worlds. PVCu is an excellent option for those desiring low maintenance requirements, but often considered a poor choice in terms of lasting aesthetics.


For many years both wood and UPVC seemed to be the preferred materials for skylights and roof lanterns. Sadly, both degrade in various ways, and have a limited life. Not only that, as far as the environment is concerned, both wood and UPVC are terrible for the carbon footprint. Aluminium however is not only durable, long lasting and infinitely stronger than wood or UPVC, it is indefinitely recyclable and is so whilst using far less energy to recycle than most other materials.

Because aluminium is so strong, this means the profiles required to give the skylight rigidity can be an awful lot slimmer than other materials. Combined with powder coating, aluminium profile can survive very happily for many years in some very harsh environments. It is also an infinitely more flexible product when it comes to colours and finishes than any other products used in the market place.

Aluminium is, however, an element that can conduct temperature. It is vital to look at products that have a full thermal break to ensure that what happens outside does not affect what is happening inside. It’s all well and good having a wonderful and efficient material, but it is another thing knowing how best to use it. Because of the above, and the fact that it is a secure product too, it is rising in popularity year on year as the preferred product for roof lanterns and skylights.

Benefits of skylights, roof lights and roof windows

Both skylights/rooflights and roof windows offer a range of benefits making them worth serious consideration by property owners. Their continued growth in popularity is attributable not just to the great design impact they can offer, but also to practical aspects including cost savings and eco-friendliness. Sunsquare’s range of high-quality, thermally-broken products – for instance – are manufactured according to the highest standards of the BSI in terms of efficiency, safety and security. And that’s without diving into the positive effects of maximal daylighting and additional ventilation in your environment.

Now you know all the crucial information about rooflights and skylights and any difference in-between, make sure to take a look at Sunsquare’s complete range of flat roof skylights and rooflights: the only BSI Kitemarked products in the UK offering sleek, contemporary style and unrivalled performance for homes and workplaces.

If you’d like to discuss the possibilities of installing a roof light window at home, either it is a opening rooflight or non opening skylight, a roof lantern or any bespoke roof window, drop us a line or call our friendly team on +44(0)1284 723377.

Written to help architects, surveyors and home improvers alike understand every UK building regulations.

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