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Flat Rooflight | Cheap Sale Prices!


First 10 sizes Clear option with or without self-clean 2-5 WORKING days delivery. Please note size selected above is the internal bottom pane glass size. To reduce excessive solar heat build-up, reduce glare and provide additional UV protection we highly recommend our BLUE or GREY tint glass.

This item is made to order
All prices are subject to 20% VAT

Custom Size
Easy fit!
Made to Measure - Made in UK
Exceptional Thermal Performance
Price Match Guarantee for like for like product
Argon gas filled Toughened Glass
Solar Protection, Noise Reduction

Our bespoke flat rooflights are perfect for visually expanding areas and other closed-in dark spaces, transforming them with daylight and stunning sky views. The seamless design with no joints ensures protection from water accumulation and mould build up. Choose a triple glazed rooflight for even more thermally efficiency.

We can also supply walk on glass rooflights. This product can be found by clicking the link below. For wall abutted rooflights or wall abutment rooflights please contact us for a custom quote.

Click here for walk on glass rooflights

What are the benefits of flat skylights?

Our flat roof skylights let in twice as much light as vertical windows and will make a great impact on your living environment. All our rooflights are made with high quality materials, making them reliable, long-lasting, attractive, and energy efficient. Our rooflights are custom-made to customer specifications to meet the desired u value required to comply with building regulations. 

We also stock fixed rooflights, roof lanterns, opening rooflights, and more. For more CUSTOM fixed, electric or manual opening rooflights and roof lanterns please view our full collection of rooflights and skylights, or contact us to find out more.

You can also learn more about the differences between flat rooflights and roof lanterns in our expert blog.

What are triple glazed rooflights?

A rooflight is simply a window that is built into the roof. It could be a small, single pane of glass, or it could be a large and expansive rooflight that accounts for most of the roof. Triple glazing is effectively three panes of glass that are separated by argon gas. This latest innovation in window insulation is a step ahead of double-glazing. 

So, with that in mind, read on to discover more about installing a triple glazed flat roof skylight.

What are the benefits of triple glazing for your flat roof skylight?

There are many benefits to gain by opting for a triple glazed rooflight over other options that are available. The main reason why people opt for triple glazing is because it is a better insulator. This means that less heat is going to escape your home through your newly installed roof light. While double-glazed flat roof lights also act as an effective barrier, triple glazing effectively adds another layer, further boosting the insulating qualities of the window. Not only does this mean a warmer home during the winter months, but it means lower energy bills too. After all, your home will stay warmer for longer, meaning you won’t need to have your central heating turned on as much. You can expect a much more peaceful home too. This is because the extra insulation also acts as a sound barrier. If that was not enough, triple glazing is also much more secure.

Now that you are aware of the best type of glazing for your roof lights, it is important to take a look at the other design elements that need to be considered when selecting flat glazed roof lights. Size is one of the major concerns here. Many customers miss out on the full range of benefits by choosing roof windows that are too small for the area of the room. Shape is also an important consideration, particularly in relation to size.

There is a common misconception that pyramid-style roof lights mean you can get more natural sunlight at a smaller size. You also need to consider what rooflight upstands you are going to choose. Upstands refer to the frames that the roof light sits in. You also need to think about roof access. If you have a roof garden, you need to insure the rooflight is just as beautiful from the exterior as it is from the interior.

Learn more about double glazing vs triple glazing in our helpful article.

Why choose Toughened Glass Systems for your triple glazed flat roof skylight?

We are flat roof window experts with years of experience in the industry. View our testimonials to see what our customers had to say about us, or read below for some key reasons to buy your flat rooflight from us.

Our flat roof window has passed strict independent testing

Unlike some of our competitors, this stepped rooflight system, once installed as per our fitting guide, has been through independent RVA accredited testing and met the requirements for Air Permeability (EN12207) and Water Tightness (EN12208).

Our flat roof windows let in more light

Please note, the size advertised on our drop-down menu is the visible bottom pane glass size – the top pane of glass is 100mm bigger all around. Most competitors will supply a rooflight with visible glass 200mm smaller than what they advertise. When comparing prices please consider this rooflight we supply lets in more light as the visible glass is larger.

Price match guarantee

We want you to get the best price for your purchase. This is why we promise to match the prices of other UK retailers.

High quality materials

We use high quality materials from reputable suppliers such as Pilkington in manufacturing our flat roof rooflights. This ensures the product is attractive and economical, with excellent thermal performance. Learn more about how rooflights can make your home more energy efficient in our helpful article.

More rooflights

As well as this rooflight for flat roofs, we also sell:

Measuring & Installation Guide

Easy fit


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 compatible low modulus 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 with Dowsil 3363. 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 and Dowsil 3363 silicone should be used. Some sealant suppliers may require primer to be applied to surfaces.

Please note all rooflights are made to order and sizes can not be changed once glass is cut or toughened. We recommend the speciation, sizes and instructions are reviewed and understood by the installer before proceeding with an order.

Technical Information

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 should undertake a risk assessment. For example, it may need to be obscure, triple glazed, bigger upstand, suitable for walking on, laminated, etc.

You can also get an flat skylights, and range of a range of roof lanterns.

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 speciation 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

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.


The product is supplied with a manufacturer’s warranty. For warranty terms please see our terms and conditions.

Delivery & Lead Time

Double 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.

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 4 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


Based on 210 reviews
Bob toploft
Bob toploft
I am the owner of Top loft company ltd, after reviewing reviews from various companies I ordered 2 juliet balconies from tgs arrived within 3 weeks, comunications and help was brilliant. Thanks for all your help.
Jim H
Jim H
Great service from the team. Easy to order, good buying guidance and clear install instructions for my builder. Rooflights look absolutely great! The team at TGS couldn't have been more helpful in organising a smaller delivery vehicle to help with restricted access. Highly recommend TGS.
Jack Smith
Jack Smith
Great service from a very knowledgeable company. Thanks team Toughened Glass Systems.
Paul Smith
Paul Smith
I was spending a lot of money on several rooflights so I wanted to make sure I got it right and I did. The professionalism, expertise and the quality of the roof lanterns really set Toughened Glass Systems apart.
Tyrone Eldridge
Tyrone Eldridge
There are no complaints about the experience with TGS. The entire process of ordering, supplying and delivering was flawless. I would really recommend you order your flat roof sky lanterns from these guys.
Robert Childers
Robert Childers
Best place for rooflights, they supply many different types and options. Thanks for all your support Toughened Glass Systems!
John Smith
John Smith
The glass balustrade gives us an amazing view onto the lake outside. So happy we ended up going for the frameless glass balcony from Toughened Glass Systems instead of one with posts
Louise Newsome
Louise Newsome
My job is to design the interiors for a lot of houses and a lot of times the hardest part was when the client wanted some really inexpensive rooflights that should look like some contemporary ones as well. That until I found Toughened Glass Systems and started working with them more and more. They have a lot of this kind of stuff at a very decent price, a price for anyone I can say. If you’re looking for cheap skylights for flat roofs or any types of roof lights, they probably have something for you.
Krystina Taylor
Krystina Taylor
Always kept us up to date with our order even when delayed by a few days. Great service from the start and good quality glass balcony delivered.