For the purposes of this article, the following definitions
shall apply:
FLOOR AREA
The actual occupied area, not including unoccupied accessory
areas or thickness of walls, except that floor area shall not include
the conversion of an existing space into a livable space, such as
a basement, as long as a septic system upgrade is not required by
the Suffolk County Department of Health Services.
SUBSTANTIAL SEPTIC SYSTEM UPGRADE
A change or upgrade to the existing septic system where the
cost of said change or upgrade equals or exceeds 50% of the cost of
the current system.