To limit the probability that the calculation of wind load on a building will not take into account the expected maximum winds at the site based on terrain roughness, the height of the surface or part thereof above ground, and hill configuration, which could lead to structural failure, which could lead to harm to persons.
To limit the probability that the calculation of wind load used for the design will not take into account the height of the surface or part thereof and shielding provided by surrounding buildings or trees, which could lead to structural failure, which could lead to harm to persons.