When it comes to buying a roof window, there is more to consider than simply the size and colour of the window. To help you choose the right roof windows for your home, we share our knowledge of roof window features and capabilities in this article with advice on how to maximise daylight, reduce energy consumption and improve the thermal performance of your house when doing so.

Pay particular attention to glazing options

It’s an area often overlooked, yet the glazing of your roof window is very important. With options ranging from our standard double glazing to triple glazing and U-values from 1.0 – 0.6 W/m².K, there is a lot to consider and we will explain a little about each glazing option and what it can offer you.

What is a U-value?

U-values are the used to measure how effective elements of materials in buildings are as insulators. The lower the U-value of a material, the more slowly heat is able to transmit through it, therefore keeping your home warmer for longer.

The Keylite range of roof windows is fitted with Thermal glazing (T) as standard. This is effectively 2 panes of glass separated by a 20mm argon gas filled cavity and a warm edge spacer, which help reduce heat transfer and the risk of condensation. Keylite Thermal glazing features a 4mm toughened outer pane and has a favourably low u-value of 1.0 W/m².K.

Hi-Therm (HT) glazing is the next step up. With a u-value of 1.0 W/m².K and warm edge space also, the key differentiator here is the 4mm toughened outer and 6mm laminated inner pane. Designed with safety in mind, this glazing is the ideal choice for windows above head height or in children’s bedrooms. This type of glazing is also effective at reducing sound and the harmful effects of UV light.
With a U-value of just 0.6 W/m².K, Triple glazing (KTG) offers maximum heat loss protection.

Make the right choices for an energy efficient roof window

If you want your roof windows to improve the energy efficiency of your home, 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, naturally 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.

In comparison with vertical windows, roof windows are much more effective allowing up to 3x more daylight than a vertical window of a similar scale!

Keylite is also the only roof window company to integrate an expanding thermal collar, creating a major improvement in thermal efficiency. With no additional components to buy and no secondary fixing required, Keylite offers this fast insulation solution to combat cold bridging by filling the gap between the window frame and the roof structure.

The significant benefit of combating cold bridging is a reduction of the condensation which can occur when warm, moist air in your home settles on cold surface, such as a window frame. This can lead to ugly black mould growth, even in new homes, where the correct balance between insulation and ventilation has not been achieved. Keylite’s thermal collar provides protection against such condensation risks.

Don’t want to install one large window?

Another option is to install 2 or more roof windows side by side or vertically. This way you not only increase the amount of natural light pouring in, you 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 your room. Take a look at our case studies of recent work for inspiration.
At Keylite, our roof windows come in a wide range of sizes, from Standard size 01, 550mm x 780mm (WxH), to Non Standard size 09G, 1340mm x 1600mm. Check out our roof windows today and select the size that best suits your needs.

Ease of Installation is important to everyone

Whether you’re a self-builder tackling the installation yourself, or a skilled tradesman with experience in fitting roof windows, the easier a roof window is to install the better! At Keylite, we have a number of innovations that ensure our windows are extremely installer friendly.

Firstly, Keylite roof windows are designed so no heavy lifting has be done outside the roof, meaning they can be fitted from inside without the need to remove the sash (although we would recommend removing the sash for the larger sized windows). As you can imagine, this allows for a much faster and safer installation. Should you need to remove the sash for any reason, our easy sash feature enables you to refit the sash into the frame in one smooth easy motion preventing the difficulties experienced while fitting many other roof windows.

We pride ourselves on the fact that you can get your window from the box to the roof in under 2 minutes, which is partly due to the pre-fitted flick-fit brackets. These brackets reduce the number of procedures normally required to secure the roof window to the prepared roof opening. For a step by step guide on installation, watch one of our easy to follow roof window installation videos.

Health and safety features to consider

Fire Escape Windows: If your roof window will be used as a fire escape, it’s imperative to check with your local planning authorities prior to specification. For a roof window to be considered as 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. Get more information on our Top Hung Fire Escape windows now.

Part F Compliance: Construction legislation requires both new and existing dwellings to be Part F Compliant and provide a means of ventilation for people in the building. Ventilation for New Dwellings is measured differently to existing dwellings as outlined below:

  • New dwelling ventilation is measured via a Whole dwelling Ventilation rate, measured in (l/s) which is determined by the number of bedrooms in a dwelling
  • For Existing dwellings, they are instead measured with an equivalent area for trickle ventilation in mm² per room instead of a whole dwelling rate in l/s.

The flow of clean, fresh air can have a great impact on health and wellbeing which is why all Keylite roof windows provide all weather ventilation. Put simply, our windows offer trickle ventilation even when the window is closed and locked, allowing the removal of stale indoor air replacing it with fresh outside air.

While we have looked at many of the main roof window features, there are countless more that we have not touched on from integral blinds right down to your choice of finishes.

For more information on these additional features, or if you need any assistance choosing the right window you can contact our expert team who would be delighted to help or alternatively, use our Product Selector tool for guidance.

We look forward to helping you in your roof window purchasing journey!

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