What is a Structural Glass Balustrade?
When the glass of a balustrade is not just used as an infill panel but is also used as the actual structure of the balustrade, it is often referred to as a structural glass balustrade. It is also sometimes referred to as a frameless glass balustrade or a cantilevered glass balustrade.
The basic idea is simple and is based on two engineering principles; a strong base that can clamp thick and strong glass panels that can resist the bending moments and loads imposed on it.
Since 2011 when BS6180 was revised, it is now possible to choose if one wants or does not want a handrail. The handrail or top section that is placed on the glass is meant to tie glasses together at the top, making the entire structure sturdier and more solid. It also must, be able to withstand the required load if one of the glass panels should break across the gap created. If one chooses to not have a handrail then laminated glass must be used, glass that can have one side break and the other side still be capable of withstanding the loads.
The Base or “Shoe” Section of the Structural Glass Balustrade
The base of the structural glass balustrade, also known in some systems as the “shoe profile”, is the most critical part that requires much design attention. The basic idea is a strong “U” channel either made from two RSAs back to back, or using aluminium designed extrusions. The glass gets fixed in place either by epoxy (two part component glue) or sometimes by a cement-type material.
As a side note it is interesting to note that in recent years much innovation has gone into these systems and now you can have base profiles that use pressure-screwed clamps or hammered-in wedges that can forsake the use of cement or epoxy glue saving on the labour previously involved with setting the glasses, not to mention the dirty process of pouring epoxy into a small channel.
The base profiles can be fixed by various materials to the balcony structure, be it steel, concrete or other material. These base profiles and their fixings need to be purpose-deigned for every site to ensure the loading and fixings can indeed withstand the large loads that will get transferred from the glass panel.
The Glass Panel
Where most balconies or balustrade systems can utilize 10mm toughened (tempered) glass, structural glass balustrades require a much stronger panel.
A minimum thickness of 15mm toughened glass panel must be employed even for residential (single family dwellings) properties. When higher loading requirements are needed, such as public areas, bars, restaurants, discothèques and malls, thicker glass panels are required. 19mm and even 25mm toughened glass panels are employed in these cases.
Because of the thickness of the glass required and the basic iron in standard float glass, when employing regular glass types a greenish type of colour is evident in structural glass balustrades a lot more than regular glass balustrade systems. This can be reduced by using “low iron” glass panels. However, one should note that these are more expensive.