Buy the Right VELUX Flashing - 5 Questions We Ask Customers

Published on Monday, 29th February 2016

Buying the right VELUX flashing kit

For every roof window you wish to install, you'll need a flashing. Flashings are designed to ensure you get a completely weathertight fit for your new or replacement window into your roofing material. That's one flashing per window - unless you're installing a number of roof windows in a combination. With the variety of roofing materials VELUX flashing kits are suitable for, it can sometimes beg the question “which one do I need?”

We want this to be an easy choice for you, without any mistakes, so we've created a guideline for you to follow before making your purchase with Sterlingbuild.

What material is on your roof?

Like your VELUX window, your flashing kit has to match the angle of your roof. It also has to complement your roofing material. It sounds obvious, but this can be overlooked!

There are three types of flashing available to suit different roofing materials: tile flashing, plain tile flashing, and slate flashing. Let's look at each one individually and talk about the requirements of each flashing.

For tiles on 15-90° pitched roof - EDW

VELUX EDW flashing kits are suitable for installing VELUX roof windows into flat or profiled roofing material up to 120mm in profile. This makes them suitable for interlocking slate, thatch and profiled sheeting. The recommended minimum pitch you can install a roof window on is 15°. If you wish to install a roof window on a pitch lower than 15°, please contact us.

For slates on 15-90° pitched roof - EDL

VELUX EDL flashing kits are suitable for installing VELUX roof windows into slates up to 8mm thick. The EDL flashing is not suitable for interlocking slates due to their chunky nature (this is where the EDW flashing would prevail).

For plain tiles on 25-90° pitched roof - EDP

VELUX EDP flashing kits are suitable for installing VELUX roof windows into plain tiles with a maximum length of 300mm. The maximum thickness of a plain tile for this type of installation is 14mm and will only work on roof pitches 25° and above.

VELUX flashing kits are suitable for different roofing materials

How about a recessed installation?

Not all of us are blessed with the vision of some roofers, and so a preview of what a window and flashing combination will look like once installed can be a difficult task. VELUX offers two installation heights: standard and recessed. The best way to describe the differences is by using VELUX’s own guidance:

“Recessed installations offer a more sleek, streamlined appearance, sitting 40mm deeper in the roof structure. Recessed installations also offer greater energy efficiency, and when installed with the appropriate VELUX insulation collar actually offer a lower certified U-value, saving energy and providing architects with greater design flexibility.”

A recessed flashing will allow your roof window to sit at the same height as your tiles or slates. When compared to the standard installation - in which the roof window protrudes from the roof by roughly 30mm - aesthetically a recessed installation looks better. If selecting the recessed flashing that comes with insulation accessories, there's the possibility to save money on your energy bills.

EDJ - for tiles on 20-90° pitched roof

VELUX EDJ recessed flashing kits are suitable for installing VELUX roof windows into flat or profiled roofing materials up to 90mm thick. The roof must have a minimum pitch of 20° for a recessed installation to work. The EDJ 2000 comes with the BDX 2000 insulation package as standard.

EDN - for slates on 20-90° pitched roof

VELUX EDN recessed flashing kits are suitable for installing VELUX roof windows into slate up to 8mm thick. The roof must have a minimum pitch of 20° for a recessed installation to work. The EDN flashing is not suitable for interlocking slates due to their chunky nature. The EDN 2000 comes with the BDX 2000 insulation package as standard.

Recessed installation allows for the roof window to be installed lower into the roof

Installation accessories can perfectly match your flashing

In recent years, building regulations relating to insulation and air-tightness of roof window installations have become more stringent. With the simple addition of an insulation accessory to a roof window installation, it guarantees to save you energy and money on your utility bills whilst ensuring an air and weather-tight installation in the process.

VELUX installation accessories to compliment your flashing

Insulation collar

The BDX insulation collar sits between the roof window frame and the structural opening in the roof, helping to insulate around the frame – reducing heat loss and eliminating cold bridges.

The BDX insulation collar is supplied with the BFX underfelt collar as standard.

Underfelt collar

The BFX underfelt collar sits around the roof window and attaches itself to the structural opening via strong, secure tape. Its task is to ensure a weather-tight seal between the roof window and the roof, ultimately stopping the elements from entering your home through the structural opening.

It’s made from a pleated, diffusion open material which whilst minimizing the risk of condensation ensures a flexible and tight seal to the underfelt of the roof, whatever its construction.

The BFX underfelt collar comes with the BDX insulation collar as standard and will not need to be purchased separately when ordering the BDX insulation collar.

Vapour barrier

The BBX vapour barrier is an accessory that helps during the installation process as well as after it. The vapour barrier helps prevent condensation from forming in the roof construction before, during and after the installation has been completed.

Made up of a fully welded rubber gasket with double pressure seal, its reinforced corners provide extra security against any perforation that could possibly take place.

Easy-to-follow installation videos

VELUX provides a simple installation guide that makes visualizing the installation process even easier than before. We've compiled a list of all of the installation videos VELUX have to offer and put them in an easy-to-find playlist for your viewing pleasure.

Simply head to our YouTube page, subscribe and you'll find the videos available to you.

Do you have any more questions?

If the answer to that question is 'yes', not to worry. We have a trained sales team who will be able to help you. Please contact us on 01304 219 922 or speak to us on our web chat.