Parapets adjacent to a roof surface must have noncombustible faces for how many inches on the uppermost section?

Parapets adjacent to a roof surface are required to have noncombustible faces extending a specific distance up the uppermost section to enhance fire safety. The requirement for a height of 18 inches is established in building codes to ensure that the parapet can effectively protect the building from potential fire exposure.

By having this noncombustible material extend for 18 inches, the design helps prevent flames from easily spreading from the roof surface to the parapet and minimizes fire risk, particularly in structures near other buildings or combustible materials. This construction detail aids in containing fires and safeguarding the integrity of the building during a fire event.

The other height options, while relevant in different contexts or specific building scenarios, do not meet the standardized requirement necessary for ensuring adequate fire protection in typical commercial building designs.