No modifications or additions to a nonconforming use or structure
shall be permitted unless they comply with this chapter. The words
"modification" and "addition" include, but are not limited to, any
alteration, addition, modification, structural repair, rebuilding
or replacement of any such existing use, structure or accessory structure
or use. Maintenance is not considered a modification; this includes
painting, decorating, paneling and other nonstructural components
and the maintenance, repair or replacement of existing private sewage
or water supply systems or connections to public utilities. Any costs
associated with the repair of a damaged structure are not considered
maintenance.