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.
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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.
Measuring & Installation Guide
Easy fit
Installation
Our roof light rooflight installation can easily be undertaken by competent builders/roofers and we provide simple step by step fitting guide and technical support to facilitate installation.
The Rooflight supplied can be installed directly on the Insulated Upstand supported by an anodized aluminium angle trim all around, supplied by the builder or roofer.
All information and diagrams on this page are for guidance only to install the rooflight we supply as each project may vary in design/construction as per architects’ drawings. Upstand design and dimensions can vary based on architects approved drawings and insulation requirements. The rooflight can be custom made to suit wider upstands with bigger than 100mm overhangs if required at additional cost.
Installation and Measuring Guide
Our rooflight installation can easily be undertaken by competent builders and roofers. We provide simple step by step fitting guide. For technical support please contact 0203 633 3224.
1. Measure the opening
2. Preparing your roof
3. Installing the rooflight
Measure the opening
The first step in purchasing your rooflight would be to measure the structural opening where the rooflight will be installed. You should allow for 5mm tolerances all around to allow the bottom pane of the rooflight to fit smoothly into the opening. As an example, if your tight opening measurements are 1010mm by 1010mm we would recommend you purchase a rooflight with a bottom pane of 1000mm by 1000mm so it slots in smoothly.
For standard units the top pane would have a black 100mm overhang all around on the top pane. This would make the overall size of the top pane 1200mm by 1200mm in this example. We can increase the size of the overhang if required if the upstand width is wider. The diagram below shows the sectional view of a double-glazed installed rooflight.
Preparing your roof
Structural glazing silicone is used to bond the double/triple glazed sealed units to the top pane to form a rooflight. The rooflight IGU is simply secured onto the timber kerb built by your roofer/builder as part of the roof construction.
The timber upstand should protrude 150mm above the roof. The recommended minimum pitch is be 5 degrees, sufficient to allow water to flow down. Sometimes customer may require installing at a lower than the recommended pitch. If choosing to do this, then we strongly advise pouring water over the top of the skylight to ensure the flow of the water is smoothly off the unit before the rooflight is installed. The only purpose of the skylight pitch is so the maximum efficiency of the self-clean coating is utilised (if selected) along with water and dirt to drift off. When installed completely flat with no pitch then the water could pool on the top of the rooflight glass which won’t affect the performance or cause leaking. You may be able to see visible water when looking up at the skylight due to the lower pitch, however the warranty is still valid, but you may notice water pooling when looking up.
Installing the rooflight
The final step to finish the roof before installing the rooflight is to apply your roof covering up to the side of the upstand to make it weatherproof as illustrated below.
The timber upstand should protrude at least 150mm above the roof and the pitch should be 5 degrees, sufficient to allow water to flow down. Please note self-clean option only works effectively at pitches of 10 degrees and above. Before sealing the product with silicone, water can be applied to test the flow off of water, if pooling occurs a higher pitch may be required.
Bottom pane should be supported on 4 sides once set in place, the aluminium angle can be fitted before the plasterboard and covered with plasterboard or fitted after the plaster board. Alternatively, a timber batten with aluminium strip on the top can be fitted to support the rooflight.
Apply adequate recommended silicone as per silicone supplier’s data sheet to the top of the Upstand firmly placing the rooflight onto the upstand. Pressure should be applied all around the 100mm overhang to ensure the silicone spreads and seals any gaps and then finish off the silicone all around with silicone tool. Once cured apply structural silicone as per supplier’s data sheet to the bottom aluminium angle trim flat surfaces firmly fitting them in place. Excess silicone should then be wiped away with a finishing tool. Dowsil 791 low modulus weather proofing silicone and Dowsil 895 Structural sealant are compatible and must be used. Setting blocks can be used to achieve sealant thickness required.
At this stage the bottom and top panes should be supported. Sealants compatible with the top of the upstand, aluminium angle trim, glass, setting blocks must be used. Sealant suppliers may require primer to be applied to certain surfaces.
Please note all rooflights are made to order and sizes can not be changed once glass is cut or toughened. We recommend the specification, sizes and instructions are reviewed and understood by the installer before proceeding with an order.
Building regs and performance
The rooflight Stepped Insulated Glazed Units (IGU’s) we supply are suitable for single storey flat roof extensions to existing residential dwellings. As each project can vary with requirements, we suggest confirming building regulation requirements for the product with the architect, builder or building officer prior to placing an order to ensure compliance. The installer or buyer should ensure that a risk assessment is carried out to confirm the product’s suitability for the project. Depending on the application, the rooflight may need to meet specific requirements, for example, it may need to be obscure, include a larger upstand, be suitable for foot traffic, or use laminated glass. For example, if the rooflights are positioned more than 5 metres above floor level, or located above swimming pools, laminated glass will be required.
Please note that the standard rooflight is supplied with toughened glass for both the internal and external panes. If laminated glass or any other specification is required, this can be provided upon request and quoted accordingly. Please note additional care needs to be taken during installation when laminated stepped rooflights are supplied, foam rope would be required to level off any discrepancies which will prevent any pressure and stop cracking on the bottom glass laminated pane.
Laminated glass consists of two panes bonded together with a plastic interlayer that holds the glass in place if broken. Toughened glass, by contrast, is a single pane that has been heat-treated and rapidly cooled to increase its strength; when broken, it shatters into small, blunt fragments. Toughened glass is a type of safety glass. While toughened glass offers greater strength and impact resistance, laminated glass provides enhanced safety and security by remaining intact after breakage.
Standard units
Our standard units are double glazed with clear toughened glass top pane manufactured to BS EN 12150 and conform to BS EN 1279, 18mm argon-fill cavity structurally sealed with toughened Low-E glass to achieve a centre pane 1.1 u-value. Glass thickness for standard size units are 6mm toughened. Glass specification and thickness will vary for larger units.
Triple and quad glazed units
Our triple and quad glazed options provide even higher performance ratings. 1.6 minimum U-value rating is currently required to comply with building regulations. The solar control layer prevents heat escaping and reflects interior heat back into the room
TGS Skylight Thermal Ratings
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-
Standard Double Glazed
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Standard Triple Glazed
Optional Extras
Coloured boarders – If required we can paint any RAL colour to the boarder which is usually 100mm wide all around.
Pilkington Activ self cleaning glass – Applied coating breaks down dirt and washes away with rain water.
Pilkington Activ blue self cleaning glass – In addition to self cleaning properties the blue tint provides additional solar control performance by keeping internal temperatures cool whilst maintaining light transmission
Triple glazed skylights – achieving 0.9 centre pane U Value rating.
Privacy glass – We can apply a sandblasted frosted layer to make the skylight obscure.
Warranty
The product is supplied with a manufacturer’s warranty. For warranty terms please see our terms and conditions.
Delivery & Lead Time
Double and Triple glazed clear with or without self-clean in sizes below can be made and delivered within 2-5 working days.
1000mm x 1000mm
1000mm x 1500mm
1000mm x 2000mm
600mm x 900mm
600mm x 1200mm
800mm x 1800mm
800mm x 800mm
800mm x 1300mm
400mm x 700mm
400mm x 1000mm
Standard manufacturing lead time for other size and specification flat roof skylights is 7–10 working days in the London/M25 and surrounding area depending on the specification. Delivery will be made from 7am to 6pm We provide a delivery date within 3 days of processing the sale. Delivery in other areas 7-12 working days. This item is delivered unpackaged on a glazing vehicle so that it can be easily inspected on delivery. You would need to ensure sufficient labour is made available on site to off load the glass from the vehicle as the the driver arrives alone and not insured to off load. Healthy and safety regulations recommend 25kg lift per person. National delivery lead times will vary.
Please note the larger sizes, at the bottom of the dropdown list above, will be on a longer lead time. Adding approximately 3 working days to the standard lead times.
Third party transport only deliver in each area on specific days of the week. We do not recommenced arranging equipment and installation until the item has been delivered.
Delivery charges on the website apply to postcodes and counties below. If delivery is outside of these postcodes/counties, please contact us.
B, BH, BN, BR, BS, CM, CO, CR, CT, CV, DA, E, EC1, EN, GL, GU, HA, HP, IG, KT, LE, LU, ME, MK, N, NN, NP, NW, OX, PE, RH, RG, RM, SS, SG, SL, SN, SM, SE, SO, SP, SW, TN, TW, W, WD, WS, WV, UB, AL, BA, WC1, IP, NG, CB, CF, DE, LS,WF,HX,HD , BL, CH,CW, DN, DT, DY, EX, HD, HR, HU, HX, L,LN,LS,M, NR,OL, S ,SK ,ST ,TA ,TF ,WA ,WF ,WN ,WR ,BD1 ,BD10 ,BD15 ,BD13 ,BD14 ,BD12 ,BD11 ,BD19 ,BD2 ,BD3 ,BD4 ,BD5 ,BD6 ,BD7 ,BD8 ,BD9 ,BD16,BD17, PO (exc I.O.W)
Essex, Kent, East Sussex, West Sussex, Hampshire, Gloucestershire, Surrey, Buckinghamshire, Oxfordshire, London, Middlesex, Hertfordshire, Bedfordshire, Northamptonshire, Leicestershire, Warwickshire, West Midlands, Nottinghamshire, Suffolk, Derbyshire, Cardiff, Cambridgeshire, Devon, Somerset, East Riding, Lincolnshire, Norfolk, Cheshire, Merseyside, Greater Manchester, south Yorkshire, Staffordshire, Rutland, Wiltshire, Worcester, Herefordshire, Dorset, West Yorkshire (BD, LS, WF, HX, HD limited postcodes)
Delivery to TQ, PL and TR postcodes will incur a higher delivery charge £150 plus vat and slightly extended delivery lead time.
Deliveries to postcodes and counties below may take up to 5 working days longer compared to our standard delivery lead times shown above:
Aberdeenshire, Angus, argyll, Carmarthenshire, Ceredigion, County Durham, Dumfries, Durham, East Lothian, East Riding, Edinburgh, Fife, Glasgow, Highland, Kinross, Midlothian, Moray, Neath Port Talbot, Ayrshire, Lanarkshire, North Yorkshire, Northumberland, Orkney, Pembrokeshire, Perth and Kinross, Powys, Renfrewshire, Scottish border, Shropshire, Stirling, Swansea, Dunbartonshire, West Lothian, Clackmannanshire, Lancashire, Cumbria
TS,FY,PR,BB,YO,FK,G,ML,DG,TD,NE,CA,DL,DH,SR,EH,KA,KY,LA,LD,PA,SA,SY,TA,AB,DD,IV,KW,PH, LL
