Final answer:
According to building codes, the minimum clear width of a stairway at and below the handrail height should be at least 2 inches when a handrail is installed on only one side.
Step-by-step explanation:
According to building codes, when a handrail is installed on only one side of a stairway, the minimum clear width at and below the handrail height should be at least 2 inches. This ensures that there is enough space for a person to safely grip the handrail while descending or ascending the stairs. The clear width is measured from the inside edge of the handrail to the opposite side of the stairway.