9 Things You Need To Know About Skylights


9 Things You Need To Know About Skylights

A glass roof is a super-effective way to pull more light into your home, but before taking the plunge, consider this expert advice.

If you’re thinking about undertaking a project to let in as much natural light as possible, there are some key points to consider. Today’s glass technology makes for an incredibly strong and durable material – it’s an essential building component – although it does have its limitations. It’s also had some incredible engineering behind it and, for a price, all sorts of styles and functions are available. Here are nine things to consider before you go ahead and factor in a skylight.

Make sure your walls can support it
This is common sense – the bigger the glazed area, the more glass there is, which can get very heavy indeed. Your structural engineer can advise you on how much weight your walls can take.

You’ll need steel supports on either side and above an opening, such as an external door, or if the roof is particularly heavy. New extensions are often constructed with a cavity wall to retain a certain amount of insulation. This is a good thing for your skylight, as the cavity can hide a steel column if you need one.

It’s also a good idea to consider the practicalities of getting the materials on-site. For example, check if your large piece of glass can fit through your main entrance door or be carried through to your garden around the side or back of your house. If not, you’ll need a crane to lift it over your property. Bear in mind potential added expenses like this.

Allow a decent budget
Glass is more expensive than bricks and other building materials. The more you wish your project to ‘disappear’ into the area around it, the more costly the system becomes.

If you would like to keep costs down, choose a glazing system with ‘off the shelf’ sizes and, if suitable, a uPVC or aluminium frame. I only say ‘if suitable’ because, when you’re applying for planning permission for an extension with a new glazed door or window, you may need to specify the material the frame will be made of, and in conservation areas, you may not be allowed to use uPVC or aluminium if this isn’t used anywhere else.

Ensure you’ll be able to clean

Skylights need a minimum slope – the absolute minimum is one percent – so rainwater will help wash away any debris, dust and leaves that settle there. Usually, a slope of five percent or more guarantees a decent enough incline to keep it relatively clean in wet weather or when you wash it.

Make sure you have a good space against which to prop a ladder safely for maintenance, whether you do it yourself or call in a window cleaning specialist.

…Or consider self-cleaning glass
Yes, there is such a thing and it does work! There’s a special, factory-applied coating that makes it harder for dust and leaves to stick to the glass, even on small inclines. It’s similar to the coating your shower screen gets.

This coating can also be retrofitted, but its quality is vastly superior when done in controlled conditions in a factory. It doesn’t mean you should skip cleaning your glazed roof entirely – once every six months is usually recommended – but it may be sufficient to simply hose it down.

Maximise light with glass beams
In this scheme, the glass roof is supported by glass beams. Adding these will probably be more expensive, but the end effect is stunning – the roof is all glazed!

These beams are toughened and laminated, and your structural engineer will calculate the size and strength they need to be. Each individual piece of glass could end up needing to be as thick as two centimetres.

Factor in window treatments
Roof windows can help you enjoy the sun all year round. However, sometimes too much sun can make it hard to function – if you want to watch TV without the glare, wish to control the light and create a more romantic atmosphere, or want to keep some of the heat out, for instance. This is when blinds or shutters are very helpful.

It’s important to think about these from the start, so there’s a designated space for them around the windows, especially if they’re custom-sized.

Alternatively, there are specialist glazing systems available that can produce the right finish for your home’s needs – for instance, if you wish to retain as little of the sun’s heat as possible and avoid a ‘greenhouse’ effect. Anti-glare finishes are available in the form of opaque films you can apply to the glass, but be aware they will make the skylight less transparent and potentially block the view.

Work with a single pane
If you would simply like to have a large piece of glass in the roof in order to brighten a dark room, and you don’t actually need it to open, then you might consider ordering a bespoke double-glazed unit. Your contractor should be able to get one ordered and fitted for you. You could even have it made to echo your dining table.

To achieve this look, you’ll need to talk with your builder and structural engineer about the size of
skylight you’d like to install, so they can judge its location, how they’ll reinforce the structure to accommodate it, and whether they’ll use double joists or small steels around the skylight’s perimeter.

Glaze your whole roof
If you’re creating or refurbishing an attic space, you could use the opportunity to glaze your roof – imagine how much light you could let in! Of course, there are privacy and overlooking issues to be considered as part of your planning and application process, but many problems can often be solved with opaque glazing or a good-quality adhesive film.

A good guide on whether you’ll be able to get the permission is to check adjacent properties. If in doubt, call your local council for advice.

Check you can walk on ground-level windows
Walk-on glass is toughened and laminated. The whole glass unit is usually fitted flush, as shown here, with a gap around it, which allows water to run down onto the waterproofing layer of the roof. In this case, the timber decking sits on top of that. This is a great option if you want to usher more light into a basement space, or into a room you’ve built under a large upstairs deck or rooftop terrace.

If a special non-slip coating is applied, sometimes in the form of sand-blasted round ‘spots’, it’s safe to walk on the glass with a reduced risk of slipping, too.

It should be noted that it does require a specific process to make sure a glazed roof can be walked on safely – and it’s very important to order it as such.


Source: Michael Schienke
Houzz UK Contributor. Chartered Architect, director and founder at Vorbild Architecture Limited.