Glass roofs and skylights

What are skylights? That depends on who you ask. 

A skylight is also sometimes called a rooflight, and can be either a window or a fixed pane of glass. They function as a light-transmitting feature for daylighting and ventilation in roof space.

This is another generic term that manufacturers often use to describe a variety of different kinds of structures, including small-scale domestic units installed on traditional pitched roofs and larger bespoke glazed units installed on flat roofs and terraces.

Consumers sometimes get confused by this term, because the products it refers to may differ quite dramatically in size, functionality, and application. The term ‘skylight’ is usually applied liberally to the same constructions as rooflights.

Roof glazing and glass skylights can safely be used throughout the roof of a building, providing a natural source of daylight that helps reduce the need for artificial lighting, while still addressing solar control and thermal insulation needs. By introducing natural daylight into the core of a building, glass roofs and skylights can help create brighter, more inviting interiors.

Which glass should be used for roof glazing?

As roof glazing is directly exposed to the sun for a high proportion of the day, careful selection of the glass is crucial, otherwise the benefits of providing more natural daylight into a building can be quickly offset by the excessive heat gain, which would make interior spaces uncomfortable for occupants. In order to select the right glass to help create a comfortable and safe environment, several factors should be considered:

Limit Overheating

In warm climates where roof glazing and skylights are exposed to the sun the whole year round, Guardian Glass recommends using a high-performance glazing solution with a maximum solar heat gain of 0.25. This will help limit the overheating of interior spaces and can contribute to reducing the need for air conditioning by helping to keep the heat outside and the cool air inside.

Help Reduce Glare

For the visual comfort of building occupants and reduced glare, Guardian Glass recommends using a high-performance glass with a Visual Light Transmission (VLT) ranging from 24 to 30%.

Safety standards for overhead glazings

Architects and designers need to consider the relevant international and/or local glazing standards relating to overhead glazing. These typically address the various building types, classifying these into different load levels, providing guidance on maximum allowable deflections and stresses for overhead glazing. Therefore, the thickness of the glass and the integrity of the insulating glass unit must be considered. For safety reasons, laminated glass (preferably heat strengthened) must be used for the internal pane of the insulating glass unit (IGU) and the outer pane of the IGU must be fully tempered.

The support system for the glass needs to be sufficient in order to prevent distortion under load. Unlike vertical glazing, loads caused by maintenance, water and the ‘dead’ load (the self-weight of the glass as a permanent load) need to be considered. If the glass roof forms part of an accessible area, it must be treated as a glass floor.

FRAMELESS GLASS DESIGNS

There are also frameless designs for roof lights and roof windows, which means that when you look up at them from inside, you only see glass.  From the outside, these products appear quite different. Roof windows, which sit flush with the surface of the roof, are aesthetically pleasing as their lines are usually as clean and as pleasing to the eye as rooflights sometimes are.

The frameless option works well if you’re looking for a structure that blends seamlessly into  your existing architecture. No matter the style of the property, frameless glass is a subtle but stylish way of allowing light to enter a space.