Ontario Building Code Practice Exam

Stairways in residential buildings are required to have a minimum width of 900 mm. This allows for safe and comfortable passage for people going up and down the stairs. Option A (750 mm) may not provide enough space for two people to pass each other comfortably, while options C (1050 mm) and D (1200 mm) may provide excess space that is not necessary and can potentially take up valuable space in the building. Therefore, option B is the most appropriate and efficient option for a residential stairway width.