rooflight vario velux frame
HOUSE EXTENSIONS
23 Jul, 2020

How to replace a rooflight in your extension

If you have an old rooflight or plastic dome in your home, and you would like to freshen up your space, then this guide will help you to plan your project properly, ensuring minimum stress and maximum satisfaction with the end result.  

From the 70s through to the 90s, there was a trend for building cubic houses with flat roofs. Many of these had squared plastic domes included in the roof, in order to ensure natural light penetrated deeper into the houses. Not only are these not very visually attractive, they aren’t very weather efficient or long lasting, leading many homeowners to seek to replace them over time.  

Why Replace Ageing Rooflights? 

During the last 10-20 years, we have seen significant progress or even a complete evolution in the design and technology of rooflights. The industry has moved from inexpensive and poorly insulated plastic products towards more premium and longer lasting glass products. Nowadays, many of us who live in houses with aging rooflights are considering how to replace them. If you fall into this category, this post will guide you towards achieving your goal of replacing your dated or damaged old rooflight with an aesthetically appealing, energy efficient and longer lasting new rooflight. 

DIY Or Professional 

The first question you need to ask yourself is whether you will do it yourself or will you hire professionals to do the replacement. If you’re going the DIY route, you need to make sure the brand of rooflight you choose has the right configuration tools and instructions available for you to do this successfully. If you’re enlisting professional help, you should still review the market yourself as what you prefer may not match with your contractor’s view of what makes the right choice. With a Vario by VELUX rooflight, we offer supply and fit, so please do feel free to get in touch with our Daylight Experts to get advice on your particular replacement. 

vario velux modular rooflight

Standard Or Bespoke 

Then, check the brand on the existing rooflight. If you can find a brand name on the rooflight, then potentially that manufacturer will have newer versions available in the same size, which will fit your need. If you cannot find a brand name on the rooflight, then you can either try to find an exact size match, change the size of the hole in your roof or order from a supplier who’ll create a bespoke measurement to fit your current rooflight’s size.  

In order to make this decision, you need to understand the measurement of the rooflight, or more specifically the opening in the roof. If your existing rooflight is more or less a standard size there will be money to be saved, as standard sized rooflights are often less expensive than bespoke rooflights. Some of the more common standard rooflight sizes are 60cm x 60cm, 80cm x 80cm, 100cm x 100cm, 120cm x 120cm, 100cm x 150cm or 90cm x 120cm. One of the most well-know and trusted suppliers of these more standard sized rooflights is VELUX. But, if your roof opening is less standard, let’s say 55cm x 200cm, you should investigate the market for bespoke rooflights. 

What Will Your Roof Support? 

Ones you have set on the size of the opening size of your roof and decided whether to go for a standard size or a size of a more bespoke nature, you should consider the state of your roof construction. When replacing older rooflights, with newer, more modern rooflights, there will often be a change in weight of the rooflight, as glass is heavier than plastic – often this change is a factor 1:6 or even 1:10 in some cases. This means you need to investigate how much load would be suitable and regulation compliant with your current roof construction.  

When replacing a rooflight, you may well need professional assistance in the form of a structural engineer or a technical architect, who can assess whether the existing roof can carry the weight of your new rooflight. If the existing construction is thought to not be able to carry the added weight, supporting elements will have to be included in the roof construction – this is certainly not impossible, but it will add some complexity and extra disruption to your project. At this point it might be worth considering whether you replace the roof in its entirety to add value to the property and longevity to the roof whilst you’re undertaking a project of this level of complexity. 

Choosing & Installing Your Rooflight 

Once you have the bearing construction covered; you are ready to order your new rooflight. When the rooflight has been installed and weathered into the roofing material, you will have to do the interior lining, in order to enjoy your new rooflight and the revitalized space in your home. The interior lining is most often done with a 15mm plasterboard or similar and then painted in the desired colours. You can learn more about how to install a rooflight in this article. 

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