What Does Your Home Say About You? - Say it with CEDRAL Roofs | Facades
07 Apr 2021

Roof Windows Explained

When it comes to roof windows, there is more to consider than simply size and colour. To help you choose the right roof windows for your build, David Loughran, Technical Team Leader at Keylite Roof Windows, discusses the various features and capabilities, advising on how the correct specification can maximise daylight, reduce energy consumption and improve the thermal performance of your home.


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As with any windows in a home, one of the first considerations for roof windows will be aesthetics. There are so many finishes available these days that you’ll be spoilt for choice, whether you want clear lacquered pine, white-painted pine or white PVC. The finish you opt for will transform your finished build, so you must consider all options before deciding on which is best for you.


It’s an area often overlooked, yet the glazing of your roof window is essential. There is a lot to consider, with options ranging from standard double glazing to triple glazing and U-values from 1.0 to 0.6W/m²K. If you are after high thermal efficiency, then triple glazing is an excellent choice. If you are building next to a busy road and would like to prioritise noise reduction, then any roof window with a laminated inner pane would be best.


Next, you should consider the operation of your chosen roof window, be it manual or electric.

Operating options include wall-mounted switches, remote control, solar power or a smart home solution where you can manage the windows via a mobile app. Your chosen opening mechanism is also essential. When specifying a roof window, consider the opening options and how they will work from both an operational and aesthetic perspective.

Thermal performance

If you want your roof windows to improve your home’s energy efficiency, one thing to think about is the glazing area. By increasing your glazing area, you improve the amount of natural light in a space while also increasing solar heat gain. The more light and heat gained, the less you rely on artificial heating and lighting systems, leading to lower household energy bills. If you are building a new home, then the energy impact of glazing will be assessed during the design process. Compared with vertical windows, roof windows allow up to three times more daylight than a vertical window of a similar scale.

Size matters

If you don’t want to install one large roof window, another option is to install two or more roof windows side by side or vertically. This way, you not only increase the amount of natural light pouring in; but also create a unique feature in your space. Combination roof windows help create the feeling of being outside, from the comfort of your home, bringing real life and character to a room.

Health and safety

If your roof window will be used as a fire escape, it’s imperative to check with your local planning authorities before specification. For a roof window to be considered a means of escape, it should have an unobstructed opening area of at least 0.33m², and the opening must be a minimum of 450mm wide and 450mm high. Similarly, construction legislation requires both new and existing dwellings to be Part F-compliant and provide a means of ventilation for people in the building.


Flashing and accessories complete your roof windows and ensure practicality as well as pleasing aesthetics. There is a range of accessories available for all types of roof windows, including security locks, opening restrictors, opening poles and blinds. Blinds come in all shapes and sizes, including electric operated and solar-powered options.

Ease of installation

Whether you’re fitting yourself or using a trusted trade professional, you should always check that the roof windows you’re specifying have been designed with ease of installation in mind. The gap between ‘as designed’ and ‘as built’ is often caused by incorrect installation. This isn’t always the installer’s fault, but often poorly-designed products. Looking out for patented design and installation features is a good start. Many manufacturers offer online step-by-step installation videos too.

Further information....

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