A use, building or structure lawfully in existence at the effective date of this chapter which shall be made nonconforming at the passage of this chapter or any applicable amendment thereto may be continued, except as otherwise provided in this article.
No existing building or premises devoted to a nonconforming use shall be enlarged, extended reconstructed, substituted or structurally altered, except when changed to a conforming use or when required to do so by law and except as follows:
A. 
Restoration and reconstruction.
(1) 
Any nonconforming use or structure damaged by fire casualty or act of God may be repaired and used as before, provided that the floor area or building area of such use, building or structure shall not exceed the floor area or building volume which existed prior to such damage. All repairs shall be completed within one year after damages occur or such use shall not be rebuilt except as a conforming use. In the event that total destruction occurs or the Zoning Officer orders said use or structure rebuilt, then the provisions of this chapter shall apply.
(2) 
When a nonconforming use or structure is destroyed or damaged beyond repair or when the owner or tenant of said use or structure desires to rebuild for any reason, the Land Use Board may authorize such rebuilding if the rebuilding would not constitute a substantial enlargement of the use and if the rebuilding would provide better aesthetics, higher setbacks or assist in alleviating existing nuisance characteristics.
[Amended at time of adoption of Code (see Ch. 1, General Provisions, Art. I)]
B. 
Repairs.
(1) 
Normal maintenance repair and incidental alterations of a structure containing a nonconforming use is permitted, provided that it does not extend the area or volume of space occupied by the nonconforming use.
(2) 
A building or other structure containing residential nonconforming uses may be altered in any way to improve interior livability, provided that it does not extend the area or volume of space currently being occupied. No structural alteration shall be made which would increase the number of dwelling units.
A nonconforming use not used for at least 90 consecutive days during a period of one year or the change of use to one permitted in a more restrictive zone or to a conforming use for any period of time shall be considered an abandonment thereof, and such nonconforming use shall not thereafter be revived.
Nothing under this article shall prevent any residence from being rebuilt or reconstructed in the event of fire or other disaster. Nothing under this article shall prevent expansion of the floor area of a residence, provided that all required setbacks, side and rear yards, open spaces and height limitations of this chapter have been met.