Notwithstanding the building height limits established in this section, no certificate of compliance shall be required for an addition to an existing dwelling or garage located within the Ridgeline and Hillside Viewshed Protection Area that results in an increase in building height of five feet or less. Incremental building height additions occurring after the date of adoption of this chapter (February 16, 2010), which result in a cumulative increase in height more than five feet of an existing building height as of February 16, 2010, shall be permitted only when a Ridgeline and Hillside Viewshed Protection Area certificate of compliance has been received.