Final answer:
According to building codes and safety regulations, any glass within 9 inches of a tread or landing has to be safety glass.
Step-by-step explanation:
According to building codes and safety regulations, any glass within 9 inches of a tread or landing has to be safety glass.
Safety glass is glass with additional safety features that make it less likely to break, or less likely to pose a threat when broken. Common designs include toughened glass, laminated glass, and wire mesh glass. Toughened glass was invented in 1874 by Francois Barthelemy Alfred Royer de la Bastie.
For it to be considered safety glass, the surface compressive stress should exceed 100 megapascals (15,000 psi). As a result of the increased surface stress, when broken the glass breaks into small rounded chunks as opposed to sharp jagged shards. Compressive surface stresses give tempered glass increased strength.
There are three levels of Optical Quality, each referring to a different optical class. Safety glasses belonging to Class 2 are of medium quality and suitable for occasional use.