Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

Name: Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9
Brand: Skylights1
SKU: fl400x3000
Availability: InStock
Rating: 5.00 (3 reviews)

Rated 5.00 out of 5 based on 3 customer ratings

(3 customer reviews)

Original price was: £981.19.Current price is: £520.00. incl. VAT

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Don’t wait until it’s too late — this exclusive discount ends the moment the timer finishes.

Skylights1 designs and manufactures the highest quality roof windows in the industry.
Leakproof by design. Durable skylights from Skylights One.

Glazing Type: Triple Glazed
Internal Size: 400 x 3000 mm
External Size: 600 x 3200 mm
U Value: 0.9 W/m²K
G Value: 58%
Sound reduction (EN 12758): 39dB
Self-cleaning glass
Net Weight: 66kg
Nationwide Delivery

⚠️ Beware of cheap skylights made with thin glass — they may sag or collect water over time.
Skylights1 uses only reinforced, thick glass for large sizes, ensuring superior strength and safety for years to come.

6 in stock

Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

OSB Insulated Upstand 400 x 3000 mm (for Flat Roof)

extra long insulated skylight upstand 400 x 3000 mm OSB base for flat roof glazing

OSB Insulated Upstand 400 x 3000 mm (for Flat Roof)

19 in stock (can be backordered)

incl. VAT

Installation kit for 1 x Flat Roof Skylight 400x3000mm

£82.70

Foam Rope - Structural Glazing Tape – 9mm Thick (7.5m Rolls)

£18.70 incl. VAT

Weatherproofing Sealant (Silicon) - DOWSIL™ 791, 310ml

£16.00 incl. VAT

Self-Cleaning Liquid Smart Glass Bottle 15ml

£19.90 incl. VAT

*Please note! Special Glass Tape and Silicone Sealant is required when installing our roof windows.
20 Year Guarantee - is valid only when using our Glass Tape and Silicone Sealant.

Payment Methods:

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Description

Flat Roof Window 400 x 3000 mm

Our premium non-opening frameless skylights are triple glazed with 6mm toughened, self-cleaning glass and a U Value of only 0.9 W/m²K.

The Flat Roof window 400 x 3000 mm is a great option for those who want to update their home extension. The unit offers a limitless view of the sky and is suitable for those who love star-filled nights. Thanks to its dimensions, you’ll have enough space to enjoy the view.

When choosing a roof light for your home, we know that safety is an important deciding factor. This product conforms to British Standards & Building Regulations and has all Safety Markings. It is CE marked, a certification mark that indicates conformity with the relevant EU directives and standards for European products. Our Skylights can be installed at a maximum pitch of 45 degrees.

Have you made your choice or are you still hesitating between different types of roof windows?

If you are looking for a custom design solution, Skylights1 can make custom size skylights that vary from our standard sizes and suit your required dimensions.

Skylight Specifications

Glazing Type: Triple Glazed
U Value: 0.9 W/m²K
Self-Cleaning: YES
20 Years Warranty
Safety Toughened and Laminated Glass
Top Glass Pane: 6 mm Planibel Clearlite / Thermally toughened glass BS EN 12150
Middle Glass Pane: 6 mm iplus Thermally toughened glass with Low-E coating EN 12150
Bottom Glass Pane: Stratobel Clearlite 44.2 / Laminated glass EN 14449

Internal Glass Size (QUOTED): 400 x 3000 mm
External Glass Size: 600 x 3200 mm
Net Weight: 66kg
Clear Tint
Аll Glass Panels
Spacer Type: 15mm Black Warm Edge
Air Gap: 15mm 90% Argon Filled
3xMore Light Than Other Brands

Before & After

Discover how a space comes to life with a Skylights1 installation.

Flood your home with daylight
Sleek, minimalist design
Outstanding insulation & UV protection
Superior energy efficiency and noise reduction
Toughened and laminated glass for maximum safety

Just one upgrade. Endless transformation.
Choose Skylights1.

For Increased Light & Security

Triple Glazed Skylights

Skylights are wonderful for getting additional natural light into your home. They are also great for increasing energy efficiency by maximising the amount of natural light that you let into your home and taking advantage of it during the day. Triple glazed skylights take this to the next level by providing a triple layer of glass, and Low-E film to ensure that your rooms are beautifully lit. They provide three layers of protection to keep your family safe and cool, which is something that any homeowner should be able to get behind.

Superior insulation

By reducing heat loss or gain, skylights with superior insulation can help to keep the interior of a building more comfortable year-round.

Increase energy efficiency

Skylights can reduce the need for artificial lighting during the day, potentially saving energy and reducing electricity costs.

Reduce noise

By blocking out exterior noise, skylights can help to reduce stress and promote a more relaxing and peaceful atmosphere.

Enhanced security

Prevent break-ins and protect against intruders. This can provide peace of mind and help to keep your home and family safe.

Keep interior cooler in summer

By keeping the interior of a building cooler, skylights can help to improve overall comfort during the hot summer months.

Reduced harmful UV radiation

Protect furniture, flooring, and other interior elements from fading and damage caused by UV exposure.

Self-Cleaning Skylight

You'll never have to clean the glass again! It's the perfect way to keep your home cleaner for longer. With zero UV emissions, this is the only window cleaner you'll ever need. Keep your home looking its best with our self-cleaning skylights!

Activation of the coating by UV radiation and natural dirtying

After installation, the special coating needs 5 to 7 days of exposure to daylight to activate.

Decomposition of the organic dirt

The coating breaks down organic dirt and also reduces the adherence of inorganic dirt.

Rain water washes away the loosened and degraded dirt.

Water droplets spread out to form a ‘sheet’. Dirt particles on the surface are picked up by water and washed off glass.

Eco-friendly Packaging

We believe in a world where our environment and the people who inhabit it live in harmony. Making a conscious effort to avoid using non-renewable resources is one of the best ways you can make a positive impact on the environment. That’s why we use only plastic-free packaging.
We use a sustainable packaging solution that provides longevity, versatility, and security. Wooden packaging is the future of shipping - why not save the Earth while you're at it?

All the plastics and components made of expanded polystyrene are eliminated, and now you can enjoy your roof windows package in the convenience of your home.

FAST UK SHIPPING

Skylights on Stock

Next Day Delivery for the London area (M25) or Free of charge 3-6 working days. We ship nationwide.

LOW PRICES

Best Value For Everyone

Our low pricing means that you can order at competitive prices, whether you are a trade or not.

20 YEARS WARRANTY

Our premium triple glazed skylights come with a 20 year warranty. You'll never have to worry about the quality again.

SECURE PAYMENT

Safe payment methods

We offer online payment methods we think are the most secure.

CUSTOMER SUPPORT

Imagine a Better World

Founded on a vision of daylight, privacy and quality of life, Skylights1 offers a complete range of high-quality skylights, roof lanterns, flashings and installation products.

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Enjoy the natural light and a warm atmosphere in your home.

✔

Improve the aesthetics of your home with our wide range of roof windows

✔

Create a better design that reflects your taste, personality and lifestyle.

✔

Enhance the quality of life with increased natural lighting in dark areas

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Increase your privacy and save money with our energy efficient products.

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Enhance the beauty of your home, make it smart, modern, and sophisticated.

Save Energy & Money

What's better than adding functionality to your home? Saving money, of course! Skylights are the perfect solution for bringing natural light into your home, which can reduce energy costs.

Our energy-efficient units are designed to provide maximum insulation and natural lighting, reducing electricity bills and ensuring you never have to worry about turning on artificial lights during the day. Get cozy this winter with the sunlight from our skylights, plus save on heating and cooling costs all year long. Create a brighter, more comfortable living space - hassle-free with Skylights1 products!

Improve Your Health

With skylights you can enjoy the health benefits of Vitamin D while also adding a beautiful aesthetic to your home. Our innovative designs will bring in plenty of natural light while providing you energy efficiency and a variety of customization options so that you can find your perfect fit.

Bringing in natural light, skylights can instantly reduce stress and anxiety while improving creativity, focus, and productivity. Our skylights come in a variety of colors, sizes, and shapes to fit any space - giving you the perfect balance of natural light year-round! With skylights, you’ll feel more connected to the world around you for an improved quality of life.

Increase Home Value

Upgrade your home with skylights - the perfect way to add natural light, ventilation, and style into your home! Our innovative design ensures that you get the most out of your window in terms of efficiency, comfort, and longevity, while adding value to your property. Whether you plan to stay in your home for years or just a couple of months, skylights will help you maximize the value when it comes time to sell.

With skylights, you'll not only improve the value of your home, but also enjoy the benefits of natural light and privacy. Plus, you can choose from a variety of styles to match your home's decor. Don't wait any longer - make your home feel more spacious and inviting with skylights today!

Electric Blinds

Roof lights and skylight windows have been a fantastic addition to most properties for many years, due to their high energy-saving qualities and their sleek and modern look. In addition to them, skylight blinds are becoming more and more popular by adjusting the amount of sunlight, entering the space and therefore keeping the temperature of your office or home in the cooler or the warmer range.

Our roof light blinds and shades add a touch of modern, luxury design to any environment and allow you to enjoy natural light at its best any time of the day.

Reasons Why Clients Choose Us

Subtle Aesthetic Vision

High Quality Materials

Easy-to-install design

Nationwide Delivery

Full Custom Skylight

3x More Light Than Other Brands

Fast Shipping

Best U-value

Argon Gas Filled

Toughened Glass

20-year Warranty

Skylight Installation

Skylights One Ltd skylights are a lot more than just roof windows.

They are some of the most beautiful, energy-saving, and innovative skylights on the market.

And now, you can install them yourself with our handy installation guide, no matter what size your opening is!

INSTALATION GUIDE

Frequently Asked Questions

What guarantees and warranties do you offer?

We offer a 20 year seal warranty on all our skylights.

Tristique parturient nulla ullamcorper at ullamcorper non orci iaculis neque augue.

What does the warranty cover?

Our warranty is CE certified and meets European standards. As long as you install your skylight unit as per our instructions, the warranty is valid for twenty years. This covers you for any defects or damages, and we offer an aftercare service.

How can I get a price?

All our Skylight prices are on our product page. Discounts may be given if an order is above £2/5000 given as a trade price. Please contact our Customer Support Team for more information if you wish to make a large order so we are able to give you a discount code.

Can I collect my Skylight in person?

Yes, you can! Once you have placed and paid for your order, please get in touch with our Customer Support Team who will arrange someone to prepare your order for collection.

May I calculate the delivery costs to my location?

Yes, you can, if you go through to checkout, it will work out the delivery costs and options without placing an order.

Do you do the installation as well?

No, we do not install. We only supply the skylights. We recommend looking for a reputable roofer within your area who can carry out the installation professionally.

Do your skylights open and close?

Yes, we offer fixed and openable skylights.

What is the max Ug-Value?

The maximum value our skylights has is 0.9 W/m²K

Can I have blinds on my Skylight?

Yes, you can have them installed once your skylight is fitted! As the installation of blinds behind the glazing increases the risk of Thermal Stress Glass Breakage, we advise you to install the blinds at a minimum distance of 150 mm from the glass.

Will it be noisy if it rains?

All our Skylights come triple-glazed which provides optimum sound insulation. This, in turn, would help minimise any rain noise. The more panes of glass, the better the noise resistance and the greater the distance between each glass, the better your sound insulation will be. All our skylights are designed with these factors in mind. We offer triple glazed skylights with 6mm toughened safety glass as standard and a generous 15mm gap between the panes and bottom. Panes are 8mm thick reducing noise to maximum.

Where are your skylights sourced from?

Our skylights are manufactured in Europe.

What makes us different from the rest of the market?

Skylights1.com guarantees in supplying top quality products at the Best Price, due to manufacturing and delivering everything in house.

What accessories will I need?

Do these come as standard or do I need to order them separately? You will need foam rope, weather proofing silicone and flashing kits along side your skylight. We have all of these on our website so you can order everything you need from us so you are ready to go.

Can I get next day delivery?

Yes, we offer express delivery to most postcodes. Please check this service on our website or give us a call.

How Can I Pay for my Skylight?

We accept PayPal, Credit and/or Debit Cards (Stripe), Google Pay, Amazon Pay and Direct Bank Transfer. You will see these payment methods offered to you upon check out. Unfortunately, we only accept payment in advance.

What pitch should my flat-roof skylight be?

It is important to have your skylight installed at a slight angle relative to the horizon to allow water to run off the glass and avoid pooling. We recommend setting the rooflight at an angle of 45°. It is worth it to spend a few extra minutes before applying the silicone to run a water test.

What is the lead time for items in stock?

Lead time depends on the size of the unit and the exact location in the UK, please add the item to your card and your delivery postcode and you will see all delivery options to your location-keep in mind that you will not be charged at this stage.

What is the maximum pitch for these skylights?

Minimum 6, maximum 45 degrees.

How do I place an order? Can i do it over the phone?

The website is the only place to place an order, and we don't take orders over the phone- but we are always contactable to answer any questions at any point.

Can I hold off on delivery if I’m not ready yet?

Yes, just let us know any instructions for delivery or delivery dates in the “notes” box during checkout.

Can I apply my own tint?

You can order a tint for your skylight by selecting the option on our custom calculator, we offer a green or blue tinted option.

Will the window need assembling upon arrival?

No, the skylights arrive ready to install (don’t forget to order your accessories separately so you can be ready to go).

Double or Triple Glazed?

Triple Glazed skylights tend to have a better U-Value and Noise Resistance. What this means is that a triple glazed skylight will have better noise reduction properties if you live in a noisy area. The lower U-Value benefit of them is that they have less heat loss. So if you plan on having a larger skylight or more than one skylight on your extension letting in more natural light we would recommend going for triple as it will save you on your energy bills and lose less heat.

Double Glazed Skylights tend to be lighter in weight and easier for installations however they are not as good on heat loss and noise reduction as triple.

Get answers to all your questions you might have.

Introducing Skylights1, your one-stop solution to brighten up any home. Get the perfect skylight for your space with our custom design options that fit any size requirement. Stop wasting time and money trying to find the right window. Our friendly team of experts are here to help you make the best choice, fast! With Skylights1, you get the perfect skylight to suit your needs!

CALL US NOW

See all sizes Skylights

Customer Reviews

3 reviews for Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

Elizabeth Foster – 25 November 2022

Rated 5 out of 5
Choosing the right roof light was made so easy with the help of the customer service team. They were patient, knowledgeable, and made sure we were confident with our choice. Our skylight arrived fast and the quality is excellent.
James Williams – 5 July 2024

Rated 5 out of 5
Top-notch experience with skylights1.co.uk! The skylights arrived promptly and were of excellent quality. The customer support team was friendly and knowledgeable, making the buying process smooth. The variety of sizes available was impressive, allowing us to find the ideal skylights for our home. The difference they have made is remarkable—our rooms are now filled with natural light. Five stars!
Jamir Trejo – 29 October 2025

Rated 5 out of 5
Installation was quick, and it hasn’t leaked a drop.

Add a review

Internal Size (quoted)	External Size
300x300mm	500x500mm
400x400mm	600x600mm
400x1500mm	600x1700mm
400x2000mm	600x2200mm
400x3000mm	600x3200mm
500x500mm	700x700mm
500x1500mm	700x1700mm
500x3000mm	700x3200mm
600x600mm	800x800mm
600x900mm	800x1100mm
600x1200mm	800x1400mm
600x1500mm	800x1700mm
600x1800mm	800x2000mm
600x2000mm	800x2200mm
600x2500mm	800x2700mm
600x3000mm	800x3200mm
800x800mm	1000x1000mm
800x1000mm	1000x1200mm
800x1200mm	1000x1400mm
800x1500mm	1000x1700mm
800x1800mm	1000x2000mm
800x2000mm	1000x2200mm
800x2500mm	1000x2700mm
1000x1000mm	1200x1200mm
1000x1200mm	1200x1400mm
1000x1500mm	1200x1700mm
1000x2000mm	1200x2200mm
1000x2500mm	1200x2700mm
1000x3000mm	1200x3200mm
1200x1200mm	1400x1400mm
1200x1800mm	1400x2000mm
1200x2000mm	1400x2200mm
1200x2500mm	1400x2700mm
1500x1500mm	1700x1700mm
1500x2000mm	1700x2200mm
1500x2500mm	1700x2700mm
1500x3000mm	1700x3200mm

Internal Size (Roof Opening)	External Size
Internal:300x300mm	External:500x500mm
Internal:400x400mm	External:600x600mm
Internal:400x1500mm	External:600x1700mm
Internal:400x2000mm	External:600x2200mm
Internal:400x3000mm	External:600x3200mm
Internal:500x500mm	External:700x700mm
Internal:500x1500mm	External:700x1700mm
Internal:500x3000mm	External:700x3200mm
Internal:600x600mm	External:800x800mm
Internal:600x900mm	External:800x1100mm
Internal:600x1200mm	External:800x1400mm
Internal:600x1500mm	External:800x1700mm
Internal:600x1800mm	External:800x2000mm
Internal:600x2000mm	External:800x2200mm
Internal:600x2500mm	External:800x2700mm
Internal:600x3000mm	External:800x3200mm
Internal:800x800mm	External:1000x1000mm
Internal:800x1000mm	External:1000x1200mm
Internal:800x1200mm	External:1000x1400mm
Internal:800x1500mm	External:1000x1700mm
Internal:800x1800mm	External:1000x2000mm
Internal:800x2000mm	External:1000x2200mm
Internal:800x2500mm	External:1000x2700mm
Internal:1000x1000mm	External:1200x1200mm
Internal:1000x1200mm	External:1200x1400mm
Internal:1000x1500mm	External:1200x1700mm
Internal:1000x2000mm	External:1200x2200mm
Internal:1000x2500mm	External:1200x2700mm
Internal:1000x3000mm	External:1200x3200mm
Internal:1200x1200mm	External:1400x1400mm
Internal:1200x1800mm	External:1400x2000mm
Internal:1200x2000mm	External:1400x2200mm
Internal:1200x2500mm	External:1400x2700mm
Internal:1500x1500mm	External:1700x1700mm
Internal:1500x2000mm	External:1700x2200mm
Internal:1500x2500mm	External:1700x2700mm
Internal:1500x3000mm	External:1700x3200mm

Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

Description

Flat Roof Window 400 x 3000 mm

Skylight Specifications

Before & After

Triple Glazed Skylights

Superior insulation

Increase energy efficiency

Reduce noise

Enhanced security

Keep interior cooler in summer

Reduced harmful UV radiation

Self-Cleaning Skylight

Activation of the coating by UV radiation and natural dirtying

Decomposition of the organic dirt

Rain water washes away the loosened and degraded dirt.

Eco-friendly Packaging

FAST UK SHIPPING

LOW PRICES

20 YEARS WARRANTY

SECURE PAYMENT

CUSTOMER SUPPORT

Imagine a Better World

Save Energy & Money

Improve Your Health

Increase Home Value

Electric Blinds

Reasons Why Clients Choose Us

Subtle Aesthetic Vision

High Quality Materials

Easy-to-install design

Nationwide Delivery

Full Custom Skylight

3x More Light Than Other Brands

Fast Shipping

Fast Shipping

Best U-value

Argon Gas Filled

Toughened Glass

20-year Warranty

Skylight Installation

Frequently Asked Questions

Get answers to all your questions you might have.

See all sizes Skylights

Customer Reviews

3 reviews for Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

Happy Customers

Happy Customers

Flat Roof Window Skylight 400 x 3000 mm, Frameless Triple Glazed, 66kg, UV 0.9

Delivery & Return

Delivery Options Overview

Exchange or Return of Goods

The following items may be returned for a refund with 15 days of purchase:

FAQ

Can I collect my Skylight in person?

May I calculate the delivery costs to my location?

Can I get next day delivery?

Can I hold off on delivery if I’m not ready yet?

Flat and Pitched Roof Skylight Installation

Flat Roof Skylight Installation Guide Video – Step by Step

Pitched Roof Skylight Installation Guide Video – Step by Step

Structural opening – provided By builder

THE WARRANTY WILL BE VOID IF A FOAM ROPE IS NOT USED AND NOT PURCHASED FROM US.

FAQ

What accessories do I need?

What pitch should my flat-roof skylight be?

What is the maximum pitch for these skylights?

Will the window need assembling upon arrival?

Do you do the installation as well?

What does the warranty cover?

Flat RoofFrameless Triple GlazedSkylights In Stock

Triple Glazed Skylights

Flat Roof
Frameless Triple Glazed
Skylights In Stock