Tempered/Toughened Glass

To comply with Building Regulations rules for human impact safety on buildings certain areas of glass is required to be a categorised ‘safety glass’. These are generally any areas of glass below 800mm to the floor, doors and door side panels under 1500mm in height. Toughened glass is one such safety glass.

It is referred to as such due to its behaviour under impact testing. When broken a toughened or tempered piece of glass shatters into small, blunt and relatively harmless pieces of glass, rather than large shards of sharp glazing that is the result of an annealed glass breakage. This reduces the risk of human injury if there is an impact with the glass panel and the unit is broken.

This breakage behaviour is a result of the tempering process. Here normal annealed or float glass is placed on roller beds and heated past its annealing point. The glass is then cooled very quickly. The result is compression stresses to the outer layers of the glass and tension stresses to the internal layers.

Tempered or ‘toughened’ glass is also five times stronger than a standard piece of annealed glass and is able to withstand higher temperature differentials to reduce its risk of thermal shock. Toughened glass is therefore an excellent choice of any external glazing where the glass will be subjected to changing temperatures.

It is possible to have shaped toughened glass panels or units with cut outs but all shaping and altering needs to be done to the glass panel before the tempering process. Please contact LAG with the locations and sizes of any cut outs needed to a toughened glass panel.