If any nonconforming building shall be destroyed by reason of windstorm, fire, explosion or other act of God or the public enemy to an extent of less than 75% of the recorded true valuation, then such destruction shall be deemed partial destruction and may be rebuilt, restored or repaired within 12 months.

Nothing in this ordinance shall prevent the strengthening or restoring to a safe condition any wall, floor or roof which has been declared unsafe by the Building Inspector.