What is the minimum glazing class for 9 square feet of glass in a door?

The correct minimum glazing class for 9 square feet of glass in a door is Class I. This classification is based on certain safety standards that are designed to minimize the risk of injury in the event of glass breakage. Class I glazing is intended for locations where human impact is less likely, and it has a low probability of shattering under normal use.

In the context of commercial buildings and building codes, the purpose of specifying glazing classes is to ensure the safety of occupants and visitors, especially in areas where doors may be frequently used. Class I glazing is made from materials designed to endure regular wear and tear while minimizing hazard.

In contrast, the higher classes of glazing are generally used in areas where there is a higher risk of impact or potential for injury, such as large windows or doors in high-traffic areas. Therefore, for a door with 9 square feet of glass, Class I is appropriate to meet safety standards without necessitating the additional features required by Classes II and above.