What is the Difference between Annealed and Tempered Glass?
August 14, 2017
When it comes to monolithic glass units in a sectional door you have the option between choosing an annealed (D/S Glass) or tempered glass. In general an 1/8” clear annealed glass will cost less than it’s tempered equivalent, however it is important to know what you are trading for the cost savings.
Annealed (D/S Glass):
Annealed or Double-Strength (D/S) glass is a non-safety float glass. It is important to know that D/S glass units are not as strong as a tempered safety glass and if broken can cause serious injury. D/S glass breaks into shards which can puncture or become embedded in clothing or flesh.
Tempered glass units are made from float glass that is heat-treated for added strength. It will take a greater force to break tempered glass than needed to break D/S glass. The additional force and characteristics of tempered glass when broken makes the glazing unit a “safety glass”.
When impacted with enough force, tempered glass will break into “beads” rather than shards. Although broken glass is dangerous, the beaded fragments of tempered glass units do not pose as great a risk as the sharp shards associated with standard D/S units.
However, it is important to note that tempered glass is subject to roller wave distortion due to the tempering process. This is not considered a defect in the glazing.