Ordinary annealed glass can break and yet remain mostly intact, resulting in the possibility of relatively large shards. The edges will be razor sharp and possibly dangerous. Safety glass is glass that either greatly minimizes the size of the broken pieces or keeps the broken pieces intact.
Tempered glass will break into hundreds of small cubes which at the most cause superficial cuts. Because it is monolithic it is usually used in applications where the glass edges are exposed, such as frameless shower doors.
Laminated glass is two panes of annealed glass¹ sandwiched together with a permanent polyvinyl butryal (PVB) interlayer. If laminated glass breaks the interlayer will hold the broken pieces together, which reduces injuries and prevents penetration of the opening. For this reason laminated glass is preferred for situations where the glass must remain intact after breakage, such as with aquariums or glass stair treads. However, laminated glass has a layered edge which does not look as nice as a polished tempered glass edge. Therefore laminated glass is usually used in applications where the edges are not exposed.
Building Code Requirements
Safety glazing is required by municipal, state, and federal laws in certain applications.
|Applications Requiring Safety Glass|
|- shower enclosures|
|- stair railings|
|- deck railings|
|- patio doors|
|- door sidelite, if the edge of the sidelite is within 24" of the door and within 60" from the floor|
|- doors and windows with lower edge within 60" from a tub or shower floor|
|- doors, if the size of the glass is equal to or larger than a 3" diameter circle|
|- any glazing within 3 horizontal feet of stairs and lower edge within 60" from the floor|
|- windows with a walk-through hazard, determined by ALL the following conditions being true: