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How to Fit a Velux Roof Window

How to Fit a Velux Roof Window

A roof window is a fantastic way of letting extra natural light into your home. Designed to be weathertight and safe, Velux windows also have a quick and simple installation.
To help you on install your perfect Velux roof window, we’ve put together this quick guide.


Before you install

Before you install your Velux roof window, you need to check the angle of your roof and determine where the window will be positioned.

The position of your window must comply with building regulations and planning permission laws. If the space is used only for occasional storage, the window can be installed in any sensible location that does not weaken the roof structure. If you have any doubts with this, talk to the building control department of your local council.

Roof windows are not recommended for roofs with an angle below 15°. This is because the water runs off shallow roofs more slowly. Shallow roofs are also more prone to wind blowing the rain back underneath the tiles or furnishings.

A centre pivot roof is great for roof angles of between 15° and 90°. For ease of use, it is also recommended to place the top frame of the window 1.85-2.20m above the floor.


How to Install

For diagrams of the stages, look at the Velux installation guide. Using the QR code on this guide, videos of each stage if installation can also be seen:


1. Create the opening

Before you create your roof opening, it is important to make sure you check for any obstructions, such as valleys, central heating vents or the ridge line. It’s also important to remember that you need the opening to be big enough to fit the flashings in as well as the physical size of the window.

The opening is created by removing the roof tiles or slates from the area. The tiles are accessed by cutting the felt underneath them, and can be removed by cutting away one of the battens from under the tile.

Once the tiles are removed, you will be able to remove the necessary roof timbers for the opening and add additional timbers to make the new framework.


2. Fit the frame

The sash (the opening part of the window) is removed from the window. Metal fixing brackets are attached the remaining frame.

The position of the metal fixing brackets depends on your type of flashing.

The type of flashing depends on the installation height of your window (either standard or recessed) and the type of roofing material.

For EDW or EDL flashings, the brackets are fitted on the top and bottom of the frame. For EDJ or EDN flashings, the brackets are fitted onto the side.

The frame is then fitted into your roof opening and secured into place.


3. Fit the flashing

Window flashing is an important aspect of your roof window and is designed to prevent water entering the gaps in your roof.

With Velux, the flashing is easy to install and will click into place around the window before being secured with a small number of screws.

Proper installation of the window flashing will create a barrier between the window and the sliding, helping to weatherproof your roof window.


4. Return the tiles/slates

Once the frame and the flashing are in place, the tiles or slates are placed back into position to the sides of the new window frame.

It’s highly likely that some of the tiles will need to be cut down to fit your new window.

Tiles are cut down using an angle grinder. When using it, make sure you are on solid ground and are wearing safety googles.


5. Fit the opening sash

The final step of your roof window installation is to refit the opening sash to the window.

Once this is in place, you can now enjoy your fantastic roof window and the natural light entering your home.



By following all these steps, you will be able to easily install your new Velux roof window and enjoy all its benefits.

If you struggle with any part of the installation, you can always contact a local tradesman for a quick and simple installation.

Ready to transform your loft space? Browse our range of Velux Roof Windows today.



Written by: Joe

Published on: 24 March 2017

Categories: Uncategorized