What Velux Flashing Do I Need?

Choosing the right flashing is one of the most important parts of correctly fitting a roof window. Velux flashing kits are designed to provide a secure, protective seal between the window itself and your roofing material. Its main job is to prevent water, debris, insects and more from entering the more vulnerable parts of your roof space.

Picking the right flashing for your Velux window and your roof type can be daunting, but you just need to know the answer to a few simple questions. The Velux flashing kit you’ll need depends on the pitch and material your roof is made of, whether you want a standard or recessed installation, how many windows are being fitted and any optional extras you may want.

We’ve written this guide as a quick introduction to the different types of flashings that are available for Velux windows, and hopefully after reading our blog you should know which flashing kit is right for your project.

Question One: What Type of Roof Do You Have?

Choosing your flashing is quite like choosing your Velux roof window in a number of ways. Firstly, the flashing kit must be compatible with your roof’s pitch and your roofing material. Different pitches and roof coverings have different requirements, so it’s important to get this right. Velux produce three main types of flashing to accompany their pitched roof windows, tile flashing, plain tile flashing and slate flashing.

EDW – for tiles on 15° - 90° pitched roofs

EDW flashing are used to install Velux roof windows into roofs with flat or profiled roofing materials with said profiles up to 120mm in size. This versatility makes them ideal for interlocking slate, thatch or profiled roofing sheets. The minimum pitch this particular flashing is suitable for is 15°.

EDL – for slates on 15° - 90° pitched roofs

These flashing kits are designed to be used when installing Velux roof windows into slates up to 8mm thick. However, this flashing it is not to be used alongside interlocking slates. This is due to their larger, thicker build. Therefore, if you have interlocking slate tiles on your roof, it is best to use the EDW flashing (see above).

EDP – for plain tiles on 25° - 90° pitched roofs

EDP flashing kits can be used alongside plain tiles that possess a maximum length of up to 300mm. The roof pitch must not be lower than 25° or higher than 90°. The maximum thickness of tiles used with this flashing must not exceed 14mm.

EAW – for tiles on 10° – 75° low pitched roofs

These low pitch flashing kits have been produced for tiled roofs that possess a profile of up to 120mm. They can sometimes be referred to as a ‘mini dormer’ flashing kit and can be used on roofs with pitches as low as 10°, whereas the usual minimum pitch of Velux flashing is 15°, making this product far more versatile. They come in a range of different sizes and are compatible with multiple Velux windows.

ZWC special header flashing kit – for roofs of any other substrate and pitches of 15° - 90°

This roof flashing has been designed for use alongside non-traditional roof materials that aren’t slate or tiles. By using this flashing kit, even roofs that don’t necessarily utilise these more popular roofing options can still enjoy a pitched roof window. The ZWC flashing can also be used when applying a pitch roof window to a self-built kerb on a flat roof. Possessing a special hood-like design that overlaps the roofing material, the flashing needs to be installed right up to the window frame to ensure maximum weather tightness and resistance.

There are also recessed flashing options for windows that are to be placed lower into the roof – read on to find out more about these useful alternatives.

Question Two: Standard or Recessed Flashing?

There is one key difference between standard flashing and recessed flashing – recessed flashing has been designed for windows that will sit around 40mm lower into the roof than standard flashing will allow. There are two different options available when it comes to recessed flashing – EDJ for tiles and EDN for slates.

EDJ – for tiles on 20° - 90° pitched roofs

A flashing for roofs with tiles up to 90mm thick, the EDJ flashing is to be installed on a roof with a 20° pitch or higher. While this minimum pitch is higher than the 15° pitches standard flashing can be used on, this is simply because recessed windows cannot be installed on roofs with lower pitches.

EDN – for slates on 20° - 90° pitched roofs

The alternative to the EDJ flashing, the EDN is to be used with slates instead of tiles. The minimum thickness of these slates should be around 8mm, which interlocking slates are not compatible with this flashing.

Question Three: How Many Velux Windows Are You Installing?

You may also need a different flashing type depending on the number of Velux windows you are installing next to each other. There are multiple different options depending on the number of windows and the positions you want to arrange them in.

Twin

Twin is a standard flashing that allows two windows to be placed next to each other with a 50mm gap between them. There are two variations available – an EBL for slate and an EBW for tiles.

Recessed Duo

Recessed duo flashing is similar to previous recessed flashing, only it allows for two windows to be placed next to each other so long as a 100mm gap exists between them. With this flashing, you get two variations – an EKN for slates and an EKJ for tiles.

Coupled

Standard couple flashing is used to place two roof windows next to each other with a 100mm gap need for maximum efficiency. There are different kinds available for slates (up to 8mm), plain tiles (up to 14mm) and tiles (profile up to 120mm). These are ‘EKL 0021E Coupled’, ‘EKP 0021E Coupled’ and ‘EKW 0021E Coupled’ respectively.

Triple

Standard triple flashing that is used in order to place three VELUX roofs next to one another. There should be a 100mm gap between each window in order for this flashing to operate properly. There are two options for both slates and tiles. Includes ‘EKL S0312 Triple’ and ‘EKW S0312 Triple.

Quattro

Quattro flashing has been designed for use when installing four windows next to each other. There should be a 100mm gap between each window in order for this flashing to operate properly. Quattro flashing can be used on slates up to 8mm thick or tiles with a profile of up to 120mm. Includes ‘EKL S0222 Quattro’ and ‘EKW S0222 Quattro’.

Question Four: Do You Want Any Accessories?

There are a few accessories available to accompany your flashing and help it, and in turn your window, operate to maximum efficiency.

Insulation collar

This collar insulates the area around the frame of the window and is positioned between the window frame and the opening of the roof. This both removes cold bridges, which can be very problematic for roof windows, and reduces heat loss considerably.

Underfelt collar

The underfelt collar should always be installed alongside the insulation collar. The collar itself provides an extremely weatherproof seal around the roof window, which works fantastically alongside the temperature maintenance properties of the insulation seal.

Vapour barrier

This extremely useful accessory prevents condensation from forming on or around your roofing window not just during installation, before and after the process has been completed as well.

You should now hopefully have a better idea of the type of flashing you will need for your project. Unlike many roofing materials, choosing flashing is rarely a process that involves a lot of picking and choosing – flashing is designed to protect your roof and your window from the elements, and only one or two will actually be viable for both your roof pitch and roofing material.

We stock a range of Velux flashing types alongside their outstanding roofing windows, with plenty of information and guides from Velux themselves to help you choose the perfect flashing type for your roof.