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Flatglass Skylights
How do I choose the correct size Skyseal Flat Glass Skylight?
To suit your own Builders Upstand
When purchasing a Glass unit without an upstand, please ensure the outside edge of your own timber upstands are positioned at the same distance as you chosen skylight size. For example, if you have a rooflight which measures 900mm x 900mm, you need to ensure the the measurement from the outside edge of your upstand is the same.
Please see image for further clarification. A 75mm wide upstand is recommended.
Skylight with UPVc Upstand
When purchasing a Glass unit with a UPVc upstand, the stated sizes represent the opening in the roof. Please ensure the opening in the roof is the same size as the purchased skylight. For example, if your skylight is 750mm x 750mm the opening in the roof also needs to be 750mm x 750mm.
What Frame colour options are there for the Skyseal Flat Glass?
The Skyseal Flat Glass is available in either Anthracite Grey (RAL 7016) or Black (RAL9005).
What Glass tint options are there for the Skyseal Flat Glass?
Our Skyseal Flat Glass is manufactured with standard clear glass. However, other options, such as low-e or self-cleaning glass, may be available upon request. Please call 02476 707700 if you would like to discuss these options.
Is the Skyseal Flat Glass available in bespoke sizes?
The Skyseal Flat Glass is available in both standard and bespoke sizes.
What is the recommended pitch for a Flat Glass roof light?
We recommend a minimum 5 degrees pitch to allow water to run off and prevent pooling on your new skylight. This can be achieved by creating a height difference in the pre-installed upstand.
Will the Skyseal Flat Glass roof light make my room cold?
The Skyseal Flat Glass uses a 24mm double glazed pane of glass which has a U-value of 1.1 W/m²K. The overall U-value of the skylight is 1.25 W/m²K. This should ensure that the heat stays in and the cold stays out.
How do I measure and choose the right size for my Skyseal Frameless Flat Glass?
Measure the internal hole size in the roof and order the rooflight in that size (e.g. If the hole in the roof is 600 x 600, this is the size rooflight you will need to to order).

What is Low-E soft coat?
Low-E soft coat glass is an advanced type of energy-efficient glazing technology specifically designed for modern skylights and windows. "Low-E" stands for "low emissivity," referring to the microscopically thin, transparent metallic coating applied to the glass surface that selectively reflects thermal radiation (heat) while allowing visible light to pass through.
This specialised coating works by reflecting infrared heat back to its source, effectively keeping your home warm during winter months by preventing indoor heat from escaping through the skylight, and cool during summer by reflecting solar heat away from your living space. The soft coat variant is particularly effective, offering superior thermal insulation properties compared to traditional glazing options.
By installing skylights with Low-E soft coat glass, homeowners can significantly improve their home's thermal envelope, reduce energy consumption for heating and cooling, lower utility bills, and create a more comfortable living environment year-round. The technology also helps minimise harmful UV radiation that can fade furnishings and flooring, providing additional protection for your interior spaces.
What is a Ceramic Border?
A ceramic border is a protective feature that blocks UV rays from damaging the seals around skylight glass, significantly extending the lifespan of the seals and preventing potential leaks or thermal inefficiencies.
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What is an Argon filled cavity?
An Argon-filled cavity is a premium insulation feature found in high-quality skylights and windows. Argon is a naturally occurring, colourless, odourless, non-toxic noble gas that is heavier than air and has superior insulating properties. In double or triple-glazed skylights, the space between glass panes is filled with Argon gas instead of regular air.
Argon gas delivers exceptional thermal performance because it has significantly lower thermal conductivity compared to standard air, meaning it drastically reduces heat transfer through the skylight. This creates a more effective thermal barrier that keeps interior heat inside during colder months and prevents external heat from entering during warmer seasons.
Beyond temperature regulation, Argon-filled skylights provide additional benefits, including improved sound insulation, reduced potential for internal condensation, and enhanced energy efficiency. These performance advantages translate to more consistent indoor comfort, lower energy bills, and reduced environmental impact through decreased energy consumption for heating and cooling. The Argon gas is securely sealed within the glass unit and maintains its insulating properties for many years, contributing to the long-term performance of your skylight.
Do I really need Triple Glazing?
Triple Glazed skylights offer impressive thermal performance with U-values as low as 0.6 W/m²K, but the practical benefits may not justify the higher costs for most homes, as quality double glazing often provides sufficient insulation with better overall value.
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What is Light Transmission?
Light Transmission is the percentage of visible light that passes through a skylight's glazing, with higher percentages allowing more natural daylight into your living space, potentially reducing the need for artificial lighting and creating a brighter interior environment.
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What is Solar Heat Reflection?
Solar Heat Reflection measures a skylight's ability to return solar energy to the atmosphere rather than allowing it to enter your home, with higher percentage values indicating greater effectiveness at keeping interior spaces cooler during warm weather.
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What is a U-value?
U-value, or thermal transmittance, is a crucial measurement that quantifies how effectively a building element prevents heat from escaping or entering a structure. Measured in Watts per square meter Kelvin (W/m²K), this standardised value is particularly important when evaluating the thermal performance of skylights and roof windows.
The U-value specifically indicates the rate of heat transfer through a building component – in this case, a Skyseal skylight. The lower the U-value, the better the thermal insulation properties and the more energy-efficient the skylight will be. This translates directly to improved temperature regulation in your home and potential savings on heating and cooling costs.
Current UK Building Regulations establish specific U-value requirements for various building elements to ensure energy efficiency standards are met. For skylights and roof windows, existing dwellings must achieve a maximum U-value of 2.2 W/m²K, while new construction projects typically require more stringent values between 1.2 and 1.7 W/m²K, depending on the specific application.
Our premium skylight range exceeds these regulatory requirements, with models featuring advanced glazing technologies that deliver exceptional U-values as low as 0.9 W/m²K in some configurations. This superior thermal performance contributes to reduced energy consumption, a smaller carbon footprint, and enhanced comfort through consistent interior temperatures regardless of external weather conditions.
What is a Thermal Break?
A thermal break is a low-conductivity material layer integrated into a skylight's aluminium frame that prevents the internal frame surface from becoming cold, effectively eliminating condensation problems while improving overall energy efficiency.
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What is Low-e Solar Glass?
Low-e solar glass features a special metallic coating that reflects heat back to its source, keeping rooms warmer in winter by retaining interior heat and cooler in summer by reflecting solar heat away, while still allowing natural light to enter.
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Any other questions?
Ask our team of inhouse experts who will be happy to have a chat and help you with your enquiry.