Please do not hesitate to contact us on  0330 123 1885 or email your requirements to where we would be happy to provide you with the most up to date lead times or work with you to find suitable alternatives

A Guide to Roof Windows


12th July 2018

If you are planning an extension or conversion to your home or need to brighten up darker spaces that do not receive much light, reading our guide to roof windows will help you make the right decision for your property.

From improved sound and thermal insulation to better ventilation - roof windows instantly add a whole new dimension to your home. This guide to roof windows will show you the basics, allowing you to reach an informed conclusion about your investment.

An Introduction to Roof Windows

Roof windows bring light and ventilation into parts of the home that are too dark or need improved air circulation. In many cases, they are added to roofs during the construction of a new extension, loft conversion or attic.

Roof Windows - Roof Stores
Roof Windows

Roof windows are usually installed between the tiles of a pitched roof and positioned horizontally, or as close as possible, on the main roof structure. They provide better views, offering continual light and acting as diffusers. This means the light is spread evenly into the room which helps to reduce harsh shadows.

There are two main components that make up a roof window, the first being the window glazing and the second the flashing kit. To the install the window into the roof you will need to use the flashing kit to ensure it remains watertight. There are several different types of flashing available, including low profile, recessed and conservation style. To get an initial idea of what flashing looks like, take a look at VELUX EDJ 2000 Flashing which is suitable for roof pitches of 20° - 90°.

Types of Roof Windows

There are numerous different styles and functionality options available to choose from when considering a roof window:

  • Top-hung roof windows: With a release handle at the base of the window and a ventilation bar further up, top-hung windows are swing open from the highest point, allowing the full sash to be pushed outwards from the wall. The VELUX GPU 0034 is a prime example of this method.
  • Centre-pivot roof windows: As the name indicates, the window opens from a mechanism positioned on both sides of the frame, spinning 180° into the centre. The VELUX White Painted GGL 2066 works in exactly the same way and also comes with triple glazing for enhanced insulation.
  • Fixed roof windows: These do not open and offer no ventilation into the room below. However, they still provide a great source of additional light for a darker space.
  • Tubular roof windows: A smaller option that is ideal for hallways, foyers and other enclosed spaces in the home. They are both easy and quick to install onto the roof.

What are the Advantages of Roof Windows?

The benefits they add to any property often make them a feature that transforms the existing space into something more liveable.

Roof Windows - Roof Stores
Roof Windows

  • More natural light: Primarily, roof windows will increase the amount of natural light where a standard vertical window is not a practical solution. Aside from conversions and extensions, they are also added to areas such as dark corridors or rooms that are separated from outside walls.
  • Create livable spaces: The increase of natural light also makes the space more habitable for regular use. This allows homeowners to maximise their property fully. This could be anything from a new home office, a studio flat, a games room, or even a new bathroom or bedroom.
  • Greater ventilation: For areas of the house such as the kitchen and bathroom, ventilation plays an important role in warding off condensation and the formation of mould and damp.
  • Sound insulation: For people living in built-up areas or in properties that suffer from external noise pollution, installing a roof window won’t cause an increase in external sound ingress. Reinforced roof windows (as well as triple glazing and 66 pane options) are available for this purpose improving the acoustic qualities of the space.
  • Increased property value: With a combination of increased light and ventilation, along with superior sound insulation and spaces maximised to their full potential, the property becomes extremely attractive to prospective buyers. This ensures that investing in a new roof window can lead to an increase in property returns.

Choosing the Right Roof Window

Once you’ve decided to install a new roof window into your property you will need to consider which type will add the most benefit to your chosen space.


The position of the roof window will have a big impact on how much light comes into the room. South-facing windows welcome more sunlight, which will be warmer during the summer. On the north side, the light is dimmer and can be a little colder during the winter.

If the roof window faces east, it will enjoy more sunlight in the morning and less in the afternoon. The opposite is true for those on the west which will rely on reflected daylight.

Roof Type

The type of roof on the property will dictate the type of window you purchase. There are specific roof windows available for pitched roofs. These can range anywhere between 15 - 90°. Flat roofs will require a window that has been manufactured specifically for that type of surface.

The VELUX GGU 0070 is a good example of a pitched roof window, while roof lanterns are a good alternative for use on flat roofs.


Roof windows provide a great source of light into spaces below and can enhance almost any type of roof. However, due to their placement, durability must be considered. For instance, if it's a flat roof and likely to experience footfall, a walk-on option would be a good choice.

Roof Windows - Roof Stores
Roof Windows


Roof windows may help to transform the look of the structure but they also provide access to the roof. If the roof is frequently in use, a fully opening window would be the best option. This will also help to increase the ventilation coming into the property.


You can choose between a manually opening window or one that opens electronically. Manually-operated roof windows are more common and affordable, especially where access is relatively simple and unrestricted.

Electric windows are more expensive but offer the ability to control windows and blinds at a touch of a button. This can be more convenient and safer in situations where access is more restricted/challenging. Common examples would be single storey extensions such as a kitchen extension where a window may be above an appliance/worktop.


Roof windows come in a variety of different shapes and sizes. This includes flat, domed, arched and pyramid. What you should take into consideration is how much ventilation is required, what kind of access you need and what the room below is being used for.

An alternative to the traditional roof window is a sun tunnel. These are available from a range of suppliers such as the Solatube DS Flat Roof Kit that significantly enhances the amount of light entering the room. The main reason why sun tunnels are considered is to provide a solution to restricted spaces. This includes hallways, bathrooms, corridors, stairwells etc.


This will depend on where the roof window is being positioned. Of course, the correct installation of a roof window should always ensure the structure remains safe. If it's being positioned in a non-typical area of the roof, then the logistics of this should be discussed at length with the contractors.

From a safety perspective, all VELUX roof windows have laminated inner panes which prevent glass from falling through in the event of breakage.  This provides an additional layer of protection for occupants.


© Roof Stores 2020 - Part of SIG plc