Glass roofs vs. Velux windows

Home extensions present you with a fantastic opportunity to modernise your property. There are loads of possible design solutions for you to choose from. Home renovation companies should guide you on the design process, by explaining the various options that are available to you. Here at Home Tales, your assigned architectural designer will help you to make informed decisions on your home extension design. If you are undertaking a ground floor extension, one of these decisions is the type of skylights or rooflights you choose to include within your roof design. 

Whether you are opting for a side return extension, a rear extension or both, it is very likely that you will be extending into the roofline of the ground floor. This presents you with a fantastic opportunity to incorporate skylights or glazing into your design. There are two main options for you to choose from. Once you’ve chosen one of these general terms, there are loads of variations, sizes, colours, frames, materials (and much more) for you to choose from.  

Option 1: Solid roof with skylights

The first option is a solid roof with skylights or velux windows installed within the roof structure. 

Option 2: All-glass roof 

In this option, a solid roof structure is never created, but instead, structural panels hold up sheets of glass which bleed from edge to edge of your roof line.

Our clients frequently consider both design solutions. We thought it would be helpful to talk you through the pros and cons of each option. 

What’s the difference visually? 

From an architectural standpoint, an all-glass roof is, generally, considered to have more of a visual impact. The large glass panels can look quite magnificent, and they give you that ‘wow’ factor lots of homeowners are after. We recently designed this incredible side and rear extension in Hackney. The homeowner opted for an exposed brick wall combined with an all-glass roof. The combination of the exposed brick interior and all-glass roof makes a big impact as it helps to merge the boundaries between inside and outside. 

With that said, Velux windows and architectural skylights come in a huge variety of shapes and sizes. This means you can select rooflights that maximise space and light within the roof structure. You will never get the glazing to bleed to the edges, like you would with an all-glass roof option. However, you can ensure that the glazing area is maximised, and that you don’t end up with a tiny window within a huge ceiling. 

Here is a project we completed in Wandsworth. The homeowner opted for these 3 large Velux windows, which run along the side return extension of the property. The combination of the Velux windows and large glass doors to the rear ensure that no corner of this room go short of natural light.

Another fantastic example of a rooflight is demonstrated in our SE19 project in Croydon. We created this beautiful flat skylight which sits over the dining area. The skylight helps to frame the ‘zone’ within the room and lights the table beautifully. We even installed LED trim within the recess of the skylight to create a feature at night too. 

What’s the difference from a cost perspective? 

Cost is a driving factor for all our projects and is perhaps the biggest influencer when it comes to decisions like these. An all-glass roof is significantly more expensive than a rooflight or Velux window option. The main reason for the high cost is the high specification requirements for the all-glass option. Glass is a very heavy material, and if you are opting to support it within thin frames, the cost for the manufacturing and installation is high. As a rule of thumb, the thinner the frames, the more expensive the product (this goes for your external doors too). A typical all-glass roof will cost between £12-18k. Velux windows are designed and manufactured in bulk, so you buy the window from a pre-existing ‘catalogue’. This means you shake that ‘bespoke’ cost. A typical Velux window will cost about £800-£1,400 + VAT. For a typical size return extension, you will fit 3 large Velux windows so the cost will be approx. £2,400-£4,200 + VAT.  

Is one easier to maintain then the other? 

Again, Velux windows take the lead here. Velux windows have been designed to rotate 180 degrees. This means you can clean the external glass very easily. You just need a ladder and a cloth! An all-glass roof will likely require a professional service to come and clean it and depending on the access routes that your property has, it might be tricky to get a thorough clean each time. 

Are there any other factors I should consider?

One factor to consider which isn’t an obvious one is timelines. Velux windows are ordered and delivered to site before they are needed. This means they are ready to install as soon the opening has been created in the roof. An all-glass roof is completely bespoke, and the glazing cannot be ordered until the walls and roof have been built up. This means there is a delay on-site, as you need to wait for the glazing manufacturer to create the product once the other items are ready on-site. All-glass roofs typically increase the build phase by 2-6 weeks depending on the timelines of the glazing supplier. 

If you want to discuss your design options in more detail, our architectural team would be delighted to speak to you. Call us on 0207 043 2378 or email us at You can also book a telephone consultation via our live diary which can be accessed here. We look forward to speaking with you more about your project. 

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