Why is it important to correctly classify terrain when assessing wind exposure?

• A. It ensures wind pressures are not underestimated
• B. To choose the fastest installation method
• C. To reduce warranty costs
• D. To simplify color matching

Answer: (B)

Classifying terrain changes the wind-load the roof must resist. Different terrain types—open, suburban, city, etc.—alter how wind accelerates and gusts interact with a surface, which in turn changes the wind pressure coefficients used in design calculations. If terrain is not classified correctly, the calculated wind pressures can be too low, leading to under-designed fastenings, membranes, or edge details that may fail in service. The purpose of getting terrain classification right is to ensure the roof system is designed to withstand the actual wind forces it will encounter, keeping performance and safety in line with standards. The other options aren’t about wind exposure: the speed of installation, warranty costs, or color matching aren’t determined by terrain classification and don’t affect the wind-load assessment.