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

A guardrail on a roof in a residential building is meant to provide safety and prevent falls. A height of 1000 mm (1 meter) is the minimum required by most building codes and regulations to ensure adequate protection.

Option A, 900 mm, is slightly lower and may not provide enough protection for individuals leaning or leaning over the railing.

Option C, 1100 mm, is slightly higher and may be more restrictive or obstructive for individuals accessing the roof or performing roof maintenance tasks.

Option D, 1200 mm, is significantly higher and would likely not be comfortable or practical for most people to lean on or see over. Therefore, B is the best answer as it falls within the recommended range for a suitable and safe guardrail height on a residential roof.