All signs, except those attached flat against the wall of a building, shall be constructed to withstand wind loads as follows:
For solid signs, twenty (20) pounds per square foot on one face of the sign. For skeleton signs, thirty-six (36) pounds per square foot of the total face area of the letters and other sign surfaces, or ten (10) pounds per square foot of the gross area of the sign as determined by the overall dimensions of the sign, whichever is greater. (Prior code § 3.06.121)