When determining the fire-resistance of a wall, which method is MOST reliable?

Analyzing both faces of the wall is the most reliable method for determining the fire-resistance of a wall because it provides a comprehensive view of the wall's performance under fire conditions. Fire-resistance ratings are based on tests that evaluate how well a wall can withstand high temperatures and structural integrity during a fire. Each face of the wall may behave differently due to factors like materials, assembly methods, and the exposure to heat.

By examining both faces, inspectors can assess whether the materials used and their configurations contribute adequately to the overall fire resistance. This holistic approach captures potential weaknesses that might not be evident if only one side is analyzed. Additionally, thorough knowledge of both sides helps ensure compliance with fire safety regulations and standards.

Relying solely on the highest test result does not account for variability in wall construction or design. Calculations can provide estimates, but they often cannot capture the complexities of actual fire behavior. Consulting original design documentation is valuable for understanding the intended fire-resistance features, but it should be supplemented with physical analysis to account for any modifications or deteriorations over time. Thus, analyzing both faces provides the most robust assessment of fire-resistance performance.