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. The construction of a deck that does not exceed 200 square
feet and that is adjacent to the exterior wall of a principal structure
is not an extension, modification or addition. The roof of the structure
may extend over a portion of the deck in order to provide safe ingress
and egress to the principal structure;