What is a Skylight? Differences between Skylights, Rooflights & Roof Windows

Every modern home nowadays needs more natural light and fresh air. Whether you're dealing with a flat roof or a pitched one, numerous solutions exist to meet your lighting needs, such as skylights. Specifically, skylights for flat roofs and pitched roof skylights can be integrated seamlessly, providing your spaces with abundant natural light.

These innovative solutions not only transform the ambiance of your rooms by allowing daylight to filter in, but they also potentially reduce your reliance on artificial lighting, contributing to energy efficiency.

Increasing the number of glazed units is a sure way of improving any internal space. It is no surprise then that solutions like skylights and other forms of sloped glazing have been increasing in popularity.

However, many homeowners struggle with the different styles of glazed units that bring natural light. Understanding the technical difference between skylights, roof windows and rooflights is important for choosing the right glazed unit.

In the following guide, we will examine these types of windows to see the main differences and how they bring light to your home.

Is it a roof window, rooflight or skylight?

Sometimes it can be tricky to know the real difference between the various glazing solutions. From the overall aesthetics and function of a rooflight and skylight, you may conclude they are the same product. But using a generic term to describe these glass units can often lead to some confusion. There are differences, which we will explain below.

What is a Skylight?

Skylights encompass the type of windows you can install on traditional-style flat and pitched roofs. They come in different styles, mostly depending on the type of roof they are being installed on. The term skylight is broad in that sense with both standardised shapes and custom options that enable the different functions a unit performs. Skylights are typically fitted to bring more natural light to the living space. They can also have an electric motor that allows them to open for improved ventilation.

What is a Rooflight?

For all intents and purposes, they are the same thing as a skylight. Rooflights are glazed units that you can typically fit on flat roofs. Some models can also be fitted on a pitched roof. They can be installed on an upstand or kerb system allowing for prolonged and heavy rainfall water to run off. The good thing about rooflights is that they come in a variety of styles and designs to suit the style of the room they are installed in. Another good thing about them is that you normally don't have to request planning permission, as they don't alter the aesthetics of the building.

What are roof windows?

A roof window is a type of window that opens outward and is an integral component of the roof's design. They are outlined under the BS EN 14351-1:2010 standard, stipulating that windows need to be installed 'in plane' with the surrounding roof and in the same orientation, most commonly under 15 degrees pitch. They are weatherproof with skirting/flashing.

Roof windows undergo a series of test conditions to advise specifiers. The declaration of performance covers things such as heavy rainfall, increased air pressure, glass deflection and air leakage that guarantee the product doesn't let in dampness and doesn't create drafts. Roof windows come in smaller sizes compared to rooflights and skylights. However, new models are now available, allowing for larger specifications.

Types of Rooflight and Skylight

Whether you are talking to a supplier directly or just browsing glazing products online, you will find a huge variety of rooflights and skylights. Below are some of the most common types of rooflights and skylights:

Opening rooflights - these can open to a specific point, which allows you to improve the amount of natural daylight and ventilation. They are good when you do not require roof access and can do with just a small opening.
Walk-on roofligths - this type is popular for terraces where pedestrian traffic is present. The units have very strong glass, while still working well to provide extra light.
Roof lanterns - these are great for letting in more natural daylight. They are a contemporary design that can fit any sort of building and flat roofs.
Electric rooflights - bringing natural light and improving ventilation is made super easy with electric rooflights. They are controlled via a panel or a remote, making them ideal for high roofs.
Tubular skylights - referred to by some as tubular daylighting devices, tubular skylights are ideal for directing light in small spaces that don't have easy access to it. Reflective material is used to direct the light and then it is dispersed at the end.
Sliding rooflights - these need no tracks, as the windows are equipped with mechanism to support their own weight. Being able to open the rooflights like that means more fresh air and more natural light.

Read our guide for more information on the different types of skylights.

Are skylights and rooflights the same thing?

Skylights and rooflights are largely similar. Both serve the same functions (to make a room more well-lit), both are in need of regular cleaning and both can have special additions like rain sensors. You can come across these terms when browsing for roof windows, and it is important to pay attention to the specifications more to know exactly what you are getting for your room.

Are roof windows and skylights the same thing?

Even though skylights and rooflights are very similar and can often be used interchangeably in various rating systems, roof windows are different. Roof windows have to be installed in the plane, whereas that is not a requirement for skylights.

Why are rooflights popular?

You can see rooflights and skylights installed flush in many homes. They are such a popular solution because they increase ventilation and can even help with energy bills. No matter type of building or room is concerned, the improved thermal performance and thermal properties, laminated glass, and good solar heat gain coefficient make such glazing products a great pick.

Do skylights always leak?

Skylights do not leak when they are installed properly. As with any roof window, they undergo tests that simulate prolonged rainfall to guarantee that they are 100% sealed. For further information on the guarantee against leaks, consult your supplier.

Frequently Asked Questions

What is the purpose of a skylight?

The main purpose of a skylight is to make the inside environment more pleasant by providing extra light and ventilating the room.

What is the difference between a skylight and a roof window?

Skylights are a bit more versatile than roof windows, which is the main difference between them. Skylights can be designed to sit flush on a pitched roof.

What is a skylight called in the UK?

The terms skylight and rooflight are often used interchangeably in the UK. Americans prefer the term skylight, but essentially both are types of roof windows that can greatly improve well being as well as contribute to saving energy.

What is considered a skylight?

A skylight is a structure or window made out of transparent/translucent glass that can be installed on all or part of a roof space in a room for daylighting and ventilation purposes.

What is the difference between a skylight and a rooflight?

There is no technical difference between a rooflight and a skylight. Both can be added to small-scale domestic units or bigger commercial buildings.

Is a rooflight a window?

A rooflight or bespoke rooflight falls within the category of windows on the roof of a room. A roof window comes in many different types, including such that can be installed on a kerb system.