The maximum area of exterior wall openings is unlimited under which condition?

The correct answer indicates that there is no limit on the maximum area of exterior wall openings when the height of these openings is between 20 to less than 25 feet. This scenario often applies to buildings where fire prevention and structural stability measures are in place, allowing for larger openings without significantly increasing the risk of fire spread or compromising the building's integrity.

In building codes and safety regulations, as the height of a wall opening increases, other factors, such as fire separation and fire-resistance ratings, come into play. Openings higher than 20 feet may be permitted to be larger since smoke and heat from a potential fire are less likely to impact lower levels immediately, and fire department access may be more feasible as well. This flexibility allows architects and builders to create more aesthetically pleasing designs without sacrificing safety.

The other options pertain to smaller height ranges, where restrictions might apply due to increased fire hazard risks and structural concerns. Such limits ensure that fire control measures are effective, as larger openings at lower heights could facilitate easier spread of fire between compartments, necessitating stricter controls on their area.