A structure that is used exclusively for the parking or storage of private motor vehicles, where for natural ventilation purposes, the exterior of the structure has uniformly distributed openings of at least 20 percent of the total perimeter wall area of each tier on two or more sides; that employs a series of interconnecting ramps between tiers permitting the movement of vehicles under their own power from and to street level. It shall be assumed that:
- Occupants, visitors and employees are awake, alert, predominantly able to exit without the assistance of others and unfamiliar with the building or structure.
- Risk of injury and risk to health assumed by occupants, visitors and employees during their use of the building or structure are predominantly involuntary and low.
- Public expectations regarding the protection afforded those occupying, visiting or working in such a building, structure or portion thereof are neither unusually high nor unusually low.