Except as otherwise provided by the declaration:

1. (1) If walls, floors, or ceilings are designated as boundaries of a unit, all lath, furring, wallboard, plasterboard, plaster, paneling, tiles, wallpaper, paint, finished flooring, and any other materials constituting any part of the finished surfaces thereof are a part of the unit, and all other portions of the walls, floors, or ceilings are a part of the common elements.
2. (2) If any chute, flue, duct, pipe, wire, conduit, bearing wall, bearing column, or any other fixture lies partially within and partially outside of the designated boundaries of a unit, any portion thereof serving only that unit is a limited common element allocated solely to that unit, and any portion thereof serving more than one unit or any portion of the common elements is a part of the common elements.
3. (3) Subject to the provisions of paragraph (2), all spaces, interior partitions, and other fixtures and improvements within the boundaries of a unit are a part of the unit.
4. (4) All exterior doors and windows and any shutters, awnings, window boxes, doorsteps, stoops, porches, balconies, patios, or other fixtures designed to serve a single unit, but located outside the unit's boundaries, are limited common elements allocated exclusively to that unit.