Ontario Building Code Practice Exam

A guardrail on a balcony in a commercial building must be at least 1100 mm in height. This is the minimum height required for safety and to prevent falls. Option A (900 mm) and option B (1000 mm) may not be tall enough to effectively protect individuals. Option D (1200 mm) is taller than the minimum requirement and may not be necessary for the specific location or purpose of the guardrail in question.