Ontario Building Code Practice Exam 2026 - Free Building Code Practice Questions and Study Guide

The minimum clearance required for a door in a residential building is 850 mm. This is determined by building codes and regulations for safety and accessibility purposes. Option A (750 mm) and B (800 mm) are both below the minimum requirement and do not provide enough space for a person using a wheelchair or other mobility aids to pass through comfortably. Option D (900 mm) is larger than the minimum requirement and is beneficial for easy maneuverability, but it is not the minimum required size. Therefore, option C is the correct answer as it meets the minimum clearance requirement for a door in a residential building.