How to replace a roof window

Person installing a VELUX roof window in a bright attic room, overlooking trees.
Is it time to replace your roof windows? Learn how to get the most out of this simple renovation project. While you're at it, don't miss out on the opportunity to transform your room with more daylight.
Key takeaways
  • If your current window is leaking, letting out too much heat, or you are not getting enough daylight into you space, you may want to consider a roof window replacement.
  • The cost of a roof window replacement depends on the kind of window you are replacing.
  • A one-for-one window replacement will take only a few hours, while a window upgrade can take 1 – 2 days. See the step-by-step guide in the article.

What to consider before replacing your roof window

A window replacement is a great way to upgrade your house, make it more energy efficient, and give it a bright makeover - and it's easier than you think! There are a few things to consider before replacing your roof window.

Better energy efficiency

If your old roof window was installed a few decades ago, chances are it is not performing as highly as it could be in terms of energy efficiency. VELUX roof windows have evolved quickly over the last few years, and their energy performance has improved greatly!

More daylight?

Not only do modern roof windows out-perform their predecessors in energy efficiency – but they also offer more daylight! Slimmer profiles in the roof window sashes mean that they have a bigger glazing area than an older model of the same size.

However, if you feel like your room could benefit from even more daylight – why not consider adding more roof windows or replacing your old roof window with a bigger solution? Our guidance is that glazing in any room should equal at least 15-20% of the floor space. Could your room be brighter?

Consider blinds

You need the right accessories to get the most out of your new roof windows. If the window replacement is in your bedroom, you must be able to shut out light at night. If you work from home, protecting yourself from the summer heat will make your home office much more comfortable. VELUX blackout blinds and / or external anti-heat blinds will solve both problems, so remember to consider what accessories you need and incorporate them in your replacement project.

How to replace a roof window

Before embarking on a home improvement project such as roof window replacement, it's a good idea to familiarise yourself with the details of the process and the cost of replacement. This will give you peace of mind when you embark on the project.

What does a roof window replacement cost?

The cost of a roof window replacement depends on the kind of replacement you want to make. The average price for a standard like-for-like VELUX roof window replacement, including the new VELUX roof window, is £980. If adding a bigger glazing area via larger or multiple windows, you should expect the installation cost and the roof window price to be higher.

If you simply replace your old windows with new, equivalent-sized roof windows, you probably don't need building permits for the replacement. If you're adding new roof windows, however, you should check the building regulations. In most cases, permission can be obtained quickly and easily.

How does it work?

A like-for-like roof window replacement can be done in as quickly as four hours, while you should expect it to take a day or two if you're upgrading to multiple and/or larger windows. The rough steps of a window replacement are as follows:

  • The installers remove the old roof window, as well as the surrounding roof tiles
  • (Optional) The installers enlarge the roof opening and potentially add supporting cross-beams on which to place the larger/ additional roof windows
  • The installers secure the frame of the new roof window(s) to the rafters of your roof while also installing the flashing kit and securing the roof tiles along the edge of the flashing
  • Inner lining is added to improve insulation and stop any moisture from passing through the opening around the roof window
  • Plaster work is done to close the internal hole around the roof window
  • The sash is added to the roof window frame(s)
  • (Optional) Blinds, shutters, and motors are installed
  • Installers clean up and take the packaging along with the old roof window

To sum up,our installers will take care of the whole process from start to finish, so you don't have to worry about anything other than enjoy your new roof windows.

“A window replacement is a great way to upgrade your house, make it more energy efficient, and give it a bright makeover - and it's easier than you think!”


VELUX Editorial team


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