(a) An on-premise or off-premise sign must be designed to resist wind loads as follows:

Wind load pressure
Height in feet in pounds for each
above ground square foot
0-5 0
6-30 20
31-50 25
51-99 35
100-199 45
200-299 50
300-399 55
400-500 60
501-800 70
Over 800 77

(b) Under this section, the height of a sign is measured above the average level of the ground adjacent to the structure.