The project proposes creating two new fixed picture-window openings in an existing exterior wall (i.e., new openings, not a like-for-like replacement within an existing opening). Clause 13 exempts from permit only the removal and replacement of exterior windows in existing openings, explicitly stating the opening size may not be altered and may not be decreased. Since the project scope involves creating new openings (not replacing within existing openings), it does not qualify for this permit exemption, and the project's preliminary assumption that a standard remodel permit pathway applies should explicitly acknowledge that the work exceeds the exempt scope defined by this clause and is not covered by the exemption.