General. The provisions of this chapter shall not apply to existing buildings at May 1, 1964, except as follows:
(1) If changes or alterations, costing in excess of 50 percent of the then value of the building, are made to an existing building, as determined by the Commissioner, such building shall be made to conform to the requirements of this chapter for new construction.
(2) If the damages to an existing building, by fire or other causes, exceed 50 percent of its then value as determined by the Commissioner, in repairing such damages it shall be made to conform in its entirety to the requirements of this chapter for new construction.
(3) If the cost of such changes or alterations or the amount of such damage indicated in the preceding sections is more than 25 percent but not more than 50 percent of the then value of the building as determined by the Commissioner, then only the portions to be changed or altered shall be made to conform to the requirements of this chapter for new construction.
(4) If the cost of such changes or alterations, or the amount of such damage indicated in the preceding sections is less than 25 percent of the then value of the building as determined by the Commissioner, minor structural changes and alterations may be made using materials which have the same strength and fire resistance as the materials of which the building is made.
(5) Alterations and changes which are not of structural character may be undertaken using materials which have the same strength and fire resistance as the materials of which the building or structure is made.
(6) No existing building shall be moved from one location to another unless such building is reconstructed or altered so that it will conform to the requirements of this chapter.
(7) The provisions of this subchapter shall not apply to structures whose assessed value is less than $1,500.
(8) Notwithstanding the provisions of any other law, any other section of this chapter, and or any other subsection of this section, reconstruction or repair of all damages to existing buildings or structures caused by Hurricane Marilyn or any subsequent natural disasters including, but not limited to, hurricanes, windstorms, rainstorms, earthquakes, tornadoes, and monsoons, which are considered total destruction of a building or structure as determined by the Commissioner, or his designee, costing in excess of fifty percent of the then value of the building or structure, as determined by the Commissioner, or his designee, and/or, any damage to existing buildings or structures substantially affecting the structural integrity of any building or structure, including but not limited to roofing, foundations, foundation walls, other permanent supports and footings, which make the building or structure unsafe or unfit for occupancy, as determined by the Commissioner, or his designee, shall be in conformance with the applicable standardized codes, or portions thereof, as provided in sections 292(f), (g), and (h) of this chapter.