If a non-complying building or other structure is damaged or destroyed by any means, including any demolition as set forth in this Section, to the extent of 75 percent or more of its total floor area, such building may be reconstructed only in accordance with the applicable district bulk regulations, except in the case of a one- or two-family residence, such residence may be reconstructed provided that such reconstruction shall not create a new non-compliance nor increase the pre-existing degree of non-compliance with the applicable bulk regulations. If the extent of such damage or destruction is less than 75 percent, a non-complying building may be reconstructed provided that such reconstruction shall not create a new non-compliance nor increase the pre-existing degree of non-compliance with the applicable bulk regulations.

In addition, the alteration of such existing building resulting in both the removal of more than 75 percent of the floor area and more than 25 percent of the perimeter walls of such existing building, and the replacement of any portion thereof, shall be considered a development for the purposes of the provisions set forth in Section 11-23 (Demolition and Replacement).

In the event that any demolition, damage or destruction of an existing building other than one- or two-family residences produces an unsafe condition requiring a Department of Buildings order or permit for further demolition of floor area to remove or rectify the unsafe condition, and the aggregate floor area demolished, damaged or destroyed including that ordered or permitted by the Department of Buildings constitutes 75 percent or more of the total floor area of such building, then such building may be reconstructed only in accordance with the applicable district bulk regulations.