In all districts, no point of any building shall be permitted to exceed the sky exposure plane (height/setback ratio) as set forth below. (See also Figures 1A and 1B and Appendix A.)[1] The following minimum number of feet of setback of a building from a property line shall be required for each one foot of building height above grade. (See Figure 1B and Appendix A.) The height above grade shall be calculated by taking the average grade along property line with perpendicular to the footprint on all four sides of the dwelling.