Picture this. You have plans for a flat roofed kitchen extension in 2026, the builder is booked for spring, and one decision is holding things up. You are comparing flat glass rooflights for that new ceiling, and every supplier claims to be the most thermally efficient, the most secure and the easiest to fit. Get it wrong and you could end up with condensation, a chilly room and a warranty that does not cover much.
Our top pick is Addlite for homeowners and self-builders who want a modern aluminium framed flat glass rooflight with verified comfort and safety credentials. Its Coxdome Lumiglaze range pairs a contemporary aluminium frame with thermally efficient glazing, a laminated inner pane, 35dB sound insulation and a 10-year manufacturer warranty. Buyers who need UKCA certified bespoke sizing and a 20-year structural warranty should consider Skylights.co.uk as the strongest alternative. EOS Rooflights is another option for selected stock units with short advertised delivery times; check the particular model before ordering.
Plenty of buyers face the same problem. Whether you are a homeowner planning an extension or loft conversion, a self-builder specifying glazing for a new house, or a contractor sourcing for a client, you need clear facts. Below you will find a ranked list of five UK suppliers, each judged on glazing specification, warranty cover, sizing flexibility and after-sales support. On 23 November 2025, The Installer reported the launch of another flat glass rooflight option for residential projects.
Our selection criteria
We kept the criteria simple and practical. You need a supplier you can trust, a compliant product and support if something goes wrong. Every company below was checked against the same four tests.
UK availability and track record
Can you buy from the company in the UK, arrange delivery to site and speak to someone who understands domestic projects? We favoured firms with a clear UK base, a defined residential offer and a history of supplying homeowners, self-builders or trade buyers.
Verifiable glazing specification
We looked for specific details that you can check instead of relying on broad claims. That includes laminated inner panes for safety, stated acoustic performance where available and thermally efficient glazing that supports compliance with Part L. Where a supplier did not publish a figure, we say so rather than making an assumption.
Meaningful warranty cover
A warranty indicates how confident a supplier is in its product. We compared what is stated, how long the cover lasts and whether it applies to the unit as a whole or only part of it. Longer structural cover is useful, although clarity matters just as much as the number of years.
Sizing flexibility and after-sales support
Your opening will not always match a standard stock size. We considered bespoke and made to measure options, standard size availability for quick jobs and whether buyers can get advice on measuring, kerbs, installation and aftercare.
At a glance
| Provider | Best for |
| Addlite | Thermal performance, acoustic insulation and 10-year warranty cover |
| Skylights.co.uk | UKCA certified bespoke sizes and 20-year structural warranty |
| Next Generation Rooflights | Bespoke structural glazing for trade and complex residential jobs |
| EOS Rooflights | Selected stock units with flexible sizing |
| TuffX Glass | Standard and bespoke UK made flat glass rooflights sold directly |
The 5 best flat glass rooflight companies in the UK
Each supplier below was assessed against those four criteria. Whether you are specifying a single unit for a kitchen extension or sourcing several units for a small development, you will find different strengths for different projects. Our number one is the best all rounder for most residential buyers, while the other four stand out in particular scenarios.
#1. Addlite – Best for thermal performance, acoustic insulation and warranty cover
Addlite stands out for residential buyers looking for a modern aluminium framed unit with clear, checkable comfort credentials.
If you are comparing flat glass rooflights for a kitchen, bedroom or garden room, the Coxdome Lumiglaze range sold through Addlite is a strong place to start. It uses a slim, contemporary aluminium frame that suits flat roofed extensions and new builds. Its thermally efficient glazing helps the room stay comfortable throughout the year. You also get a laminated inner pane, which addresses safety glazing compliance without requiring an upgrade or optional extra.
Sound matters more than many people expect, particularly on a busy road or under a flight path. The stated 35dB sound insulation gives you a specific figure to assess instead of a general promise of quiet. The 10-year manufacturer warranty also gives you a stated period of cover. Buying is direct through Addlite rather than a wide merchant network, so you deal with a specialist team from the initial enquiry through to delivery.
You should still check the structural opening, kerb height and roof build up before ordering. Addlite lists ten standard fixed sizes for this Coxdome product, with mainland UK delivery in 1–3 working days. Other upstands and opening options are available, but some require a separate enquiry, so confirm the specification before ordering.
Pros
- Laminated inner pane included for safety glazing compliance
- Stated 35dB sound insulation provides a verifiable acoustic figure
- 10-year manufacturer warranty for long term peace of mind
- Contemporary aluminium frame suited to extensions and self-builds
- Thermally efficient glazing supports Part L compliance and comfort
Cons
- Available directly from Addlite rather than across a wide merchant network
- The published 1.0 W/m²K U-value is for the centre pane; request the whole-unit figure for your chosen size
- Some upstand and opening options require a separate enquiry rather than an online selection
- Delivery outside mainland UK requires an enquiry
Who it’s best for: homeowners and self-builders who prioritise thermal performance, acoustic comfort and warranty cover in a modern aluminium framed unit.
#2. Skylights.co.uk – Best for UKCA certified bespoke sizing and long structural warranty
Skylights.co.uk is the pick for buyers who need a certified, made to measure unit backed by the longest stated structural cover in this list.
This is the trading name of an established UK manufacturing group based in London, operating with UKCA and ISO certification. That independent certification matters when you are working with building control, an architect or a warranty provider. Bespoke sizing and engineering support form the core of the offer, allowing non-standard openings, large panes or architect specified details to be accommodated instead of forced into a stock size.
Delivery within the UK is described as fast, which helps when your roofer has an available slot and you cannot wait weeks for the glass. The headline 20-year structural warranty is among the longest offered by a UK rooflight supplier, providing useful reassurance on larger or higher value projects. For self-builders who want their paperwork in order, the combination of certification and long cover is a persuasive one.
The trade off is the level of detail available on everyday comfort specifications. No particular glazing U-value or acoustic figure was confirmed in the information available, so you will need to request the data sheet for your chosen size and specification. Pricing is also available on application, which is normal for bespoke work but less convenient when preparing a quick budget.
Pros
- 20-year structural warranty, the longest stated cover in this roundup
- UKCA and ISO certification providing independent quality assurance
- Bespoke sizes and engineering support for non-standard projects
- Fast UK delivery stated to assist with project planning
Cons
- No confirmed U-value or acoustic specification in the available facts
- Pricing on application, so you cannot prepare a budget from a list price
- Manufacturer direct model, which may be less suitable if you want a local reseller relationship
Who it’s best for: buyers who need certified bespoke sizing and maximum structural warranty, especially for architect led extensions and self-builds.
#3. Next Generation Rooflights – Best for bespoke trade and complex residential specifications
Next Generation Rooflights is well suited to jobs that are not straightforward and require a specialist to help resolve the details.
Based in Mildenhall in Suffolk, this operating UK manufacturer focuses on bespoke rooflights and structural glazing for residential and commercial projects. Its work includes large flat units, walk on glass, structural assemblies and designs where an architect has drawn something unusual that needs to be built properly. The team describes its work as bringing architectural visions to life, and this design led approach is reflected in the way it handles one off specifications.
Dealing directly with a maker has clear advantages for contractors and architects. You can discuss kerb details, loadings, access and interfaces with the roof build up instead of selecting a standard option from a catalogue. The business serves homes as well as light commercial projects, so its team is familiar with the paperwork and coordination involved in larger jobs.
It is a relatively small team, which makes capacity planning important if you need several units at short notice. No particular frame type, U-value or warranty duration was confirmed in the available facts, so approach the company as a specialist offering advice and a project specific quotation. Ask for test data, drawings and written warranty terms before committing.
Pros
- Specialises in bespoke and structural glazing for complex briefs
- UK manufacturing base with access to direct technical discussion
- Experience across both residential and commercial sectors
- Suited to architect specified and contractor led projects
Cons
- Small team, so lead times and capacity require checking for larger orders
- No confirmed U-value, frame or warranty details in the available facts
- Project specific pricing means allowing time for quotation and review
Who it’s best for: trade buyers, contractors and architects specifying bespoke or structural glazing for larger or more complex jobs.
#4. EOS Rooflights – Best for selected stock units and flexible sizing
EOS Rooflights is a practical choice when you find a suitable stocked unit and can confirm its delivery date.
The company manufactures and sells rooflights, roof lanterns and skylights for residential and commercial projects from its base in Sidcup in Kent, with offices also in London. Selected standard stock units advertise 2–5 day delivery, while other products and bespoke sizes have longer lead times. If your builder has already formed an opening in the roof, confirm availability for the specific size and model before booking the installation.
Flexible sizing options are another advantage. You are not restricted to one square size, while the broader range of lanterns and flat units may be useful when combining products across a single extension. The business is described as offering high safety standards, which is reassuring for family homes, but you should still confirm the precise glazing make up for your order.
Check availability if you are ordering for a development rather than one home. EOS publishes whole-rooflight U-values and warranty terms for its ranges, but these differ by product and component. Request the specification for your chosen unit, and confirm stock and delivery before booking your roofer.
Pros
- Short advertised delivery on selected stock units for time sensitive projects
- Flexible sizing for a range of residential project types
- Broader product range covering rooflights, lanterns and skylights
- UK based operation with residential and commercial experience
Cons
- Small team, so confirm scalability for multi unit commercial orders
- Lead times vary by model and size, with bespoke units taking longer than stock products
- Availability can vary, making it important to check stock and delivery before booking labour
Who it’s best for: homeowners and residential contractors who need a selected standard sized unit quickly, with some flexibility on dimensions.
#5. TuffX Glass – Best for direct purchase of standard and bespoke UK made flat rooflights
TuffX Glass manufactures and sells flat glass rooflights directly, with framed and frameless options for homeowners as well as trade buyers.
The business is an established British glass manufacturer based at Knowsley Business Park in Prescot, Merseyside. Its Infinity range includes standard sizes that can be ordered online and made to measure options. Framed units have thermally broken aluminium frames, while frameless glass units offer a different low profile finish.
TuffX publishes glazing and frame information, stock sizes, delivery windows and a 10-year guarantee for its products. Check the specification for the particular framed or frameless unit you want: glazing options and installation requirements differ across the range.
Pros
- UK manufacturing base in Merseyside
- Direct ordering from the manufacturer, with standard and bespoke options
Cons
- Bespoke finishes and non-standard specifications can take longer than stock units
- Check delivery terms for your postcode and selected glazing option
Who it’s best for: homeowners and trade buyers comparing standard or bespoke UK made flat glass rooflights sold directly by their manufacturer.
What to look for in flat glass rooflights
Getting these five basics right will help you avoid most problems. They apply whether you are buying one unit for a kitchen or several for a new build.
Start with thermal performance. Under Part L, you need a rooflight that helps the whole extension meet the required energy standard, so request the U-value for the complete unit in your size rather than relying on the centre pane figure. A lower U-value means less heat loss, although the frame, kerb and installation detail all affect the finished result. A 16 September 2026 Glazing Today article describes a new Velux mid-market product. Compare data sheets rather than assuming products in the same price band perform alike.
Check the safety glazing as well. For overhead glass, ask the supplier to confirm the inner pane specification and relevant safety requirements for your installation; Approved Document K covers protection against impact with glazing in England. The frame also deserves attention. Aluminium frames suit modern flat roofs because they are slim, stable and low maintenance, but you should check the colour, thermal break and how the unit fixes to your timber or insulated kerb.
Sizing and customisation are the next considerations. Measure the structural opening instead of the old unit, then confirm whether the supplier works to external kerb dimensions or overall glass size. Compare the warranties carefully too. A 10-year manufacturer warranty on the unit is strong for residential work, while longer structural cover may be useful on bespoke projects. Check what the warranty covers, what it excludes and who you need to contact if the unit leaks.
Frequently asked questions
What should you look for in flat glass rooflights?
Look for four things you can verify. Begin with a UK supplier that has a real base and a clear delivery and returns process. Check for a stated glazing specification that includes a laminated inner pane and a whole unit U-value supporting Part L compliance. You also need meaningful warranty cover with the exclusions clearly explained, along with sizing flexibility and practical advice on kerbs and installation. Request data sheets in writing instead of relying on headline claims alone. Comparing flat glass rooflights on those four points will quickly show which supplier fits your project.
Which option is best for a residential extension or self-build?
For most kitchens, bedrooms and garden rooms, choose a thermally efficient aluminium framed unit with a laminated inner pane, stated acoustic performance and a solid manufacturer warranty. This combination addresses comfort and safety while providing long term confidence. If your opening is non-standard or architect specified, prioritise a supplier offering bespoke engineering and certification. When the programme is tight, standard sizes with confirmed fast delivery should move higher up your list.
What U-value should you aim for to meet building regulations?
Part L sets energy standards for the whole building, so there is no single magic number for the glass alone. In practice, ask for the lowest whole unit U-value you can afford in your required size and check how the kerb and upstand affect installed performance. Your supplier should provide the unit U-value for your specification, while your designer or building control officer can confirm that it works within the overall extension calculation. A centre pane figure is not a substitute for the whole unit figure.
What is the difference between a flat glass rooflight and a roof lantern?
A flat glass rooflight sits low over the roof, combining a slim profile with a single expanse of glass. It suits modern extensions where you want daylight without substantially changing the roofline. A roof lantern is a raised structure with pitched glass sections and a ridge, adding height, architectural detail and sometimes broader sky views. Lanterns can cost more to make and fit, require more cleaning and alter the appearance of the roof. For a minimal contemporary finish, begin with a flat unit.
The right supplier for your scenario
If you recognise your project in that opening scenario, the choice comes down to your priorities. For comfort, safety and long term cover in a family extension or self-build, choose Addlite for its Coxdome Lumiglaze specification with an aluminium frame, laminated inner pane, 35dB acoustics and 10-year warranty. Buyers who need a bespoke size with certified paperwork and maximum structural cover should choose Skylights.co.uk. For a complex trade or architectural brief, talk to Next Generation Rooflights. Consider EOS Rooflights when a suitable stock unit has a confirmed delivery date. TuffX Glass offers UK made framed and frameless units for direct purchase, including standard and bespoke sizes. Match the supplier to your scenario and your new flat glass rooflights should deliver what you bought them for: more daylight without the draughts, noise or worry.
