8 questions to consider before choosing a glass roof for your extension

Nov 17, 2023 | Property News

Glass ceilings can add a serious “wow” factor to any home extension or renovation, allowing significant amounts of natural light to flow into the room. However, there a number of things you should consider before you decide on adding a glass roof – here are eight of the most important questions you will face.

What is your budget?

This question is central to any renovation or building project. We would all like to spend like money is no object, but in reality we all have financial constraints and they will impact your choice of glass roof.

On average, a glass roof will cost between £1,200 – £2,000 per m². Prices can vary massively depending on the type of glass ceiling you are looking to add, but you can be certain that adding glass to your ceiling will be notably more expensive than a more traditional brick and slate roof.

Frameless glazing is the most impressive option but requires structural glass and is therefore also one of the most expensive. Meanwhile, metal or uPVC frames will bring costs down a little while still offering much of the natural light.

Do you understand the building regulations?

Building regulations matter and are there for your safety. They set out that you must have a qualified structural engineer give proper consideration to the structural integrity of your space, and how much your walls or roof will need to be reinforced if you plan to add glass panels.

Another part of the regulations, Section 10.2 of Part L, stipulates that “the area of windows, roof windows, rooflights and doors should not exceed 25% of the total floor area of the dwelling.” When you include all these elements, it is quite easy to accidentally go over that 25% limit, so it is always good to work with a team of professionals, from architects to structural engineers, to make sure any extension you build is both structurally safe and complies with the regulations.

Single or multi-panel glass roof?

If the ceiling area you plan to cover with glass is relatively small, then a single pane will be your best option for an uninterrupted view. For larger areas, you might want to use multiple panels together. If you want to enjoy the maximum amount of natural light, you could opt for glass beams to fit your panels, but these do cost a premium.

Glass panel or roof window?

If you are simply looking to add a glass section to your roof to bring in more natural light, then a simple panel will be a more cost-effective option. However, if you also want to add some ventilation, then you might want to opt for a roof window.

These roof windows, often made by brands such as Velux, can add some much needed ventilation to a room, especially if the room does not have any other windows such as with a roof extension. However, for rooms with very high ceilings where you would need either a ladder or a pole to open the roof windows, then you should ask yourself whether you would actually go to all that trouble. In these situations, maybe a simple glass panel would be a better choice.

How will you keep the glass clean?

Glass roofs can attract dirt and get covered in leaves and other debris during the autumn and winter months. As such, it is important to think about how you might clean these windows in the future.

You might be fine with extendable sponges, or the toughened glass panel from a basement extension may be at ground height with easy access. Alternatively, you might decide that paying a professional to come in and clean the window once a year makes the most sense for you.

Another option is to choose self-cleaning glass panels. These panels have a special coating added to them that is activated by the Sun’s rays and breaks down any dirt that is then washed away when it rains. This relatively recent invention can save you a lot of effort, but it does come at an additional cost.

Too hot or on view?

Glass roofs bring in floods of glorious natural light, but in the summer months, the heat from those rays could make the room too hot and stuffy. To counter this, you could opt for a solar control coating on the glass which will let the light though but block out some of the heat.

Similarly, in a densely populated area like London, you might want to enjoy the light coming into your rooms but would prefer if the neighbours could not also see into your extension. In this case, a privacy coating could be applied to the glass panels which would let you still look out to the sky, but would obscure the view of anyone looking in from outside.

Do you need toughened glass?

If the glass panel is from a basement extension and it makes up some of the exterior patio floor, then you should always use toughened glass to avoid any cracks or breakages as people walk across. If the panel is a few stories up, where only birds or a curious cat might wander, then a standard glass panel should be perfectly fine.

How are you going to prevent condensation?

As with any glass windows, rooflights can attract condensation. The build-up of moisture on rooflights can be a particular problem for basement extensions where there is walk-on glass in the garden space due to the difference between internal and external temperatures. To combat this ‘cold bridging’, premium rooflights can be installed with thermal breaks, which are effectively areas of insulation that reduce heat conductivity built into the frame. Ventilation, to allow air to circulate via fans and regularly opening the windows, is also always important in keeping condensation levels low, but rooflights with thermal breaks are another useful addition to the toolkit.

If you are unsure of which type of glass roof might work best for your extension or renovation, or are uncertain about the best way to get natural light into your living space, then call Good London Builders today to get the expert advice you need.

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