Which flashing kit to choose for pitch roof windows

Flashing kits are a must if you are planning to install a pitch roof window as they are the most important part of the window. Flashings are responsible for keeping your roof windows weatherproof and prevent water leaking. Most of the problems with leaking windows are due to incorrect installation or wrong flashing kit used for installation.

Flashing kits have to be the same brand/make as the windows and in the same size as your window. These installation parts are not interchangeable so when you are choosing the pitch roof window make sure you are choosing the same brand and size flashing kit. For example the Velux flashing kits will not be suitable for Sunlux or Optilight brand windows and vice versa.

If you are choosing the roof windows on our website, you can find the flashing kits on the product page under the accessories on the same page.

Choosing the right flashing kit for your roofing material is very important. When it comes to picking the correct flashing kit when buying a pitch roof window you would need to know what type of roofing material you will use.

The two of the most popular roofing materials are tiles either corrugated or thick flat or a standard slates.



The tile flashing kits it’s the most universal flashing kit and it can be used on either corrugated ( wavy ) tiles or high profiled flat tiles and will work with most of the interlocking tiles.  Depending on the window manufacturer the tile flashing kits are suitable for tiles with maximum thickness of 45mm ( Optilight ) to 120mm in profile ( Velux ).

The bottom part of the tile flashing kits is finished with an EPDM or lead apron to accommodate the change in height and allow the rain water to be directed onto the roof.


The slate flashing kits can be used on natural or man-made slates with thickness up to 8mm. Slate roofing material is used on the roof pitch above 20 degrees.

If you measure the thickness of your slate and if it’s thicker than 8mm most likely it would be a tile. Slate flashing kits can not be used on interlocking slates due to their thickness. In that case you would need to use a tile flashing kit instead. 

The above flashing kits are the two of the most popular roofing materials.


The 3rd type of flashing kits is the plain flashing kit for plain tiles. Plain tiles are a simple rectangular shape and fairly small in size, commonly 265 x 165 mm.

Plain flashing kits are for plain tiles with the thickness between 12mm -16mm.

If you are in doubt you can ask your installer as most of the experienced installers would tell you what kit to use or contact us and we will try our best to advise you about the correct flashing kit for your roof covering.