The glass product most often associated with fire rating is polished wired glass. It has provided fire protection for more than 100 years. In North America, wired glass is typically rated for 45 minutes in light sizes up to 9 square feet (1,296 square inches), with a 90 minute rating restricted to 100 square inches for use in fire doors. The biggest advantage of wired glass may be its low cost.
Polished Wired Glass is far and away the most well known product in the industry. It has a solid track record. Most codes were originally written around wired glass, because for many years it was the only glass that could pass the fire testing. Wired glass is able to pass the hose stream test, and has earned a 45 minute rating (even higher in very small door sizes). Code and fire officials have been able to instantly recognize the wire mesh as a sign that glass was fire-rated.
In some instances, however, that same wire mesh has presented an undesirable "institutional" image. And occasionally, people have mistakenly assumed that the wire mesh makes the glass more impact resistant. Truth be told, wired glass is a relatively weak glass that only meets minimal 100 ft./lb. impact standards. With that in mind, even though wired glass is readily available and easily affordable, great care should be taken if it is installed in areas where impact safety is a concern, such as schools and other high traffic areas. Some schools, with liability issues in mind, use high impact fire-rated glass – even if initial costs are higher.