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Flat Roof Skylight 500 x 500 mm Original price was: £ 280,00.Current price is: £ 212,00. incl. VAT

Flat Roof Skylight 400 x 400 mm

£ 201,00 incl. VAT

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Regal Glass Group: A trusted manufacturer of premium roof windows

Type: Fixed Frameless Flat Roof Skylight
Internal Size: 400 x 400 mm
External Size: 600 x 600 mm
Glazing Type: Triple Glazed
Net Weight: 10.20kg
U Value: 0.9 W/m²K
G Value: 58%
Light transmittance : τv [%] 72
Sound reduction (EN 12758): 39dB
UV transmission : τuv [%] 0

Experience the excellence of Regal Glass Group’s roof windows, featuring these impressive technical characteristics.

This item: Flat Roof Skylight 400 x 400 mm
£ 201,00 incl. VAT
£ 201,00 incl. VAT
£ 39,00 incl. VAT
£ 24,00 incl. VAT
£ 15,00 incl. VAT
£ 30,00 incl. VAT

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Easy Returns

Hassle-free returns within 30 days.

10 Year Warranty

Enjoy peace of mind with our extensive warranty.

Frameless Skylights Glass Performance

Experience the perfect blend of natural light, energy efficiency, noise reduction, and UV protection with our precision-engineered glass.

Modern Design
Solar energy transmittance (G value): g [%] 65
UV transmission : 0 τuv [%]
Light transmittance: τv [%] 72
Thermal transmittance (U value): : 0.9 [W/(m².K)]
Min 3.0 [W/(m².K)] / Max 0.1 [W/(m².K)] 70%
Shading coefficient: 0.66 SC
( Maximum SC 1.00 / Maximum SC 0.20 ) 42%
Sound Reduction: 39 dB (-2;-7)
( Maximum 40dB / Minimum 30dB ) 90%

Easy to replicate
Installation Guide

Dive into our user-friendly Installation Guide for a smooth skylight setup. Get the clarity you need, step-by-step.

Click below to explore the full guide.

Discover the elegance and functionality of the Flat Roof Skylight 400 x 400 mm, brought to you by Regal Glass Group. This skylight window, ideal for flat roofs, embodies the perfect blend of style, performance, and durability, ensuring your space is not only well-lit but also energy-efficient.

Featuring advanced triple-glazed units, this skylight achieves an outstanding thermal efficiency with a U-value of 0.9 W/m²K. This is made possible by the innovative 15-millimeter warm Edge spacer between the glass panes, filled with Argon gas to significantly reduce heat transfer. This design ensures that the interior remains comfortable throughout the year, regardless of external temperatures.

The frameless design of our skylight windows stands out for its minimalistic elegance, seamlessly integrating into any architectural style without compromising on insulation capabilities. The sleek, modern appearance enhances the aesthetic of your space while providing exceptional thermal performance, as indicated by the impressively low U-value.

Moreover, the self-cleaning feature of our skylights simplifies maintenance. Activated by sunlight, this feature works to dissolve and wash away any surface contaminants, maintaining a spotless view with minimal effort.Suitable for installation angles ranging from a subtle 6 degrees to a more pronounced 45 degrees, these skylights are versatile enough to fit various design requirements. They also offer enhanced sound reduction, UV protection, and are constructed with safety toughened glass for your safety and peace of mind.

Complying with British Standards & Building Regulations, the Flat Roof Skylight 400 x 400 mm comes with all necessary Safety Markings and is CE marked, ensuring it meets the stringent EU directives and standards for quality and safety.

At Regal Glass Group, we understand the importance of choice and customization. That’s why, in addition to our range of standard size skylights that are readily available in stock, we proudly offer custom skylight solutions tailored to your unique requirements. Whether you’re enhancing a residential space or illuminating a commercial venue, our skylights are designed to bring light, elegance, and efficiency to any setting.


10 , 20 kg


65 × 10 × 65 cm


Regal Glass


Regal Glass Group Ltd

Internal Size

400 x 400 mm

External Size

600 x 600 mm

Glazing Type

Triple glazed

Glass Tint

Clear Tint



Roof Type

Flat Roof , Pitched Roof

Skylight Type


Top Glass Pane:

6 mm Planibel Clearlite / Thermally toughened

Air Gap

16 mm Argon 90%

Middle Glass Pane:

4 mm Planibel Clearlite Thermally toughened

Air Gap

16 mm Argon 90%

Bottom Glass Pane:

Stratobel Clearlite 44.2 with iplus 1.1 pos.5

Spacer Type

15mm Black Warm Edge

U value

0.9 [W/(m².K)]

Sound reduction - EN 12758

[dB] 39 (-2;-7)

Light transmittance: tv [%]


External light refection : ρv [%]


Internal light refection : ρvi [%]


Colour rendering index : Ra [%]


Solar energy transmittance : g [%]


Shading coefcient : SC




UV transmission : τuv [%]



2 reviews

2 reviews for Flat Roof Skylight 400 x 400 mm

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  1. Isabella Evans

    We chose a 400 x 400 mm skylight for our small bathroom, and it’s our best decision. The natural light it lets in makes the space feel so much larger and more welcoming. Regal Glass Group’s quality is superb!

  2. Peter Armstrong

    Bought a skylight for my client’s kitchen. Good quality and easy to install.

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