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Transform your space with our stunning frameless flat glass rooflights.  Designed to flood your space with natural light, flat rooflights open up any room, creating a warm, inviting atmosphere year-round. Enjoy expansive sky views, a closer connection to nature, and a sleek, contemporary design – perfect for a space that inspires calm and comfort. Get yours today in a custom size and enjoy Fast UK Delivery and our Best Price Guarantee. If you’re shopping around, view our most popular categories: Rooflights, Skylights & Roof Windows Roof Lanterns Opening Skylights And most popular products: Triple-Glazed Rooflight: Self-Cleaning Glass Electric & Manual Opening Rooflights  Korniche Roof Lantern Framed Flat Skylights Korniche Flat Lite   Sleek, frameless designs for bright homes Sleek and contemporary, our frameless flat skylights refresh your home’s look and create spaces you’ll love spending time in. Plus, they let in up to twice as much light as normal windows, creating brighter, more welcoming rooms and supporting better mood, focus, and wellbeing.  Bespoke sizes Our bespoke size offering means you can choose a size that perfectly fits your space rather than shoehorn a standard size into a room it doesn’t suit. Easy installation Our skylights are quick and easy to install. Click the ‘Measuring and Installation’ tab above to find step-by-step instructions and technical information. Quality glass We use argon gas filled toughened glass with solar protection and noise reduction for long-lasting performance. If you require laminated glass, or have any other specifications, get in touch and we can quote accordingly.  Fully compliant and built to perform All our features are designed to comply with building regulations and thermal performance markers. Double-glazed rooflights achieve a centre pane 1.1 u-value, with triple-glazed features performing even better. Manufacturer’s warranty included We offer a full manufacturer’s warranty. View our terms and conditions for more information. Fast UK Delivery and Best Price Guarantee Our flat rooflight comes with Fast UK Delivery and a Best Price Guarantee, meaning you won’t find a better deal anywhere else. Flat roof window experts you can trust Toughened Glass Systems is an industry leader when it comes to flat roof windows. In over a decade of trading, we’ve supplied thousands of flat rooflights to clients all over the UK, gaining hundreds of 5-star reviews in the process. Learn more about us and get in touch to start your new flat rooflight project today. Product FAQs Can you install a rooflight on a flat roof? Yes, you can install a rooflight on a flat roof, and it’s a very common way to bring natural light into extensions, kitchens, living spaces, offices, and commercial buildings. Just bear in mind the following conditions: A minimum fall of 5 degrees is required to allow rainwater to run off and prevent pooling, staining, and damp issues Correct positioning matters, as south-facing aspects receive the most sunlight UV-filtering glass can be specified to reduce heat and UV exposure while still maximising natural light What is a flat rooflight? A flat rooflight – also known as a flat skylight or flat roof window – is a glass window fitted to the flat roof of a home to increase natural light and improve the room’s overall aesthetic.  What roof pitch are flat rooflights for? Flat rooflights must be installed at a minimum pitch of 5°. Installations exceeding 15° will require either a pitched rooflight or additional weatherproofing provided by the installer, allowing the product to be fitted at pitches of up to 45°. The rooflight must also be installed on an upstand with a minimum height of 150mm above roof level. Why choose a flat rooflight? Flat rooflights are a great alternative to traditional windows. They offer more natural light, require no wall space, and feature superior designs that elevate your home’s aesthetic. What type of skylight is best for a flat roof? The majority of skylights and roof lanterns can be fitted to flat roofs, so what’s best for you will depend what you’re after. If you want a bold design that extends beyond your roof, a roof lantern is your best option. If you’d prefer a more minimalistic design, flat rooflights are perfect. Our flat rooflight is by far our most popular product, so you’re in good company if you decide it’s for you. What size flat rooflight should I choose? We advise you choose a rooflight that’s between 15% to 25% of your room’s total floor space. We can help work that out for you, so don’t hesitate to get in touch. Do I require double or triple-glazed? Our double-glazed rooflights offer excellent thermal performance, preventing draughts and heat loss and ensuring your home stays warm in the colder months. However, if you want that extra layer of insulation, triple-glazed is your best bet. We recommend our triple-glazed rooflight. We’re happy to help you decide based on your project details, budget, and location. How much glass am I going to see once the frameless flat glass rooflight is installed? Once installed, a frameless flat glass rooflight appears almost entirely as glass from inside, with around 90–95% visible glass. You’ll barely notice the slim edge where it meets the ceiling. Can flat skylights be used in commercial settings? Yes, flat rooflights are as stunning in commercial settings as they are in residential properties. Whether you’re looking for a rooflight for a shop, office, cafe, or something else, get in touch and we can help. Where would you recommend fitting flat rooflights? We’ve provided skylights for almost every space you can think of, from living rooms and kitchens to bedrooms, bathrooms, and lofts. Learn more about where to position skylights in our guide. Performance FAQs What type of skylight is best for a flat roof? Bespoke, flat, frameless skylights are the most popular type of rooflights for flat roofs. They’re visually stunning, significantly increase natural light, and perform reliably for years when fitted correctly. Do flat skylights leak often? As long as you buy quality features from a trusted company and have them properly fitted by a professional, your skylights won’t leak. Do flat skylights make a room hotter in summer? Like any windows, flat rooflights can increase room temperature in the summer if they receive direct, unobstructed sunlight, However, modern specs, low-E coatings and advanced glazing options mitigate this, while blinds, or shades can ensure your room stays cool. Are flat rooflights energy efficient? When properly installed and bought from a trusted seller, flat rooflights are highly energy efficient. All our products meet relevant requirements and guarantee strong thermal performance. Do flat rooflights open for ventilation? This flat rooflight doesn’t open, so view our range of opening skylights if you’d prefer a ventilated option. Planning & regulation FAQs Do I need planning permission for a flat rooflight in the UK? You generally don’t need planning permission for a flat rooflight in the UK, although we recommend checking to be on the safe side. Regardless, all our products are designed to meet planning permission regulations. Do flat roof skylights need to comply with building regulations? Yes, flat roof windows must comply with UK building regulations regarding structural safety, thermal performance, and ventilation. Again, all our features meet these regulations, but if you have any questions feel free to get in touch. Can a flat rooflight be installed on an extension? Yes! We sell lots of flat rooflights to homeowners carrying out single-storey home extensions.  Cost & installation FAQs How hard is it to fit a skylight to a flat roof? Installing a skylight on a flat roof is usually a straightforward job for a builder or handyman and can typically be done without replacing the roof. However, it needs to be installed with the correct 5-degree slope for drainage, along with proper waterproofing and structural checks to prevent leaks and ensure safety. How do you install a rooflight on a flat roof? Follow the simple instructions on our installation tab to see how to install our skylight for flat roofs? How much does a flat rooflight cost in the UK? The price of a flat rooflight really depends on the size and features you go for. Our most popular flat rooflight ranges from £259.00 – £2,800.00 (excl. VAT), while our triple-glazed option is available from £163.00 – £619.00 (excl. VAT)*. *Prices correct as of March 2026 How much does it cost to install a flat roof skylight? Again, this will depend on the scope of your project, but you can expect to pay about £1,000 on average. How long does it take to install a flat roof window? If carried out by professionals, you can expect a flat roof installation to take around 4 to 6 hours. How much does it cost to replace a skylight in the UK? Buying a replacement skylight will cost the same amount as buying a new skylight. However, if you’re buying the same size, installation will be cheaper, and is likely to cost between £500 to £800. Can a flat rooflight be installed on an extension? Yes! We sell lots of flat rooflights to homeowners carrying out single-storey home extensions. Maintenance & longevity FAQs How long do flat roof skylights last? If you buy your skylight from a trusted company and have it installed by professionals, you can expect it to last from 15 to 25 years. If you spot signs of wear after this time period, it may be time to buy a replacement. Do flat roof windows require much maintenance? Flat rooflights require minimal maintenance. Clean them a few times a year and periodically remove debris and check the sealant and frame to ensure there’s no deterioration. View our blog for guidance: How to Clean Roof Lanterns & Skylights: Inside and Out. Are flat skylights safe and secure? Yes, flat rooflights are incredibly safe and secure when properly designed and installed. We use durable glass and materials for maximum security.