(2) For purposes of subsection (a)(2) of this section, any development or proposed development of private property within the boundary of the Scenic Area that is significantly different from, or a significant expansion of, development existing as of June 1, 1984, shall be considered by the Secretary as detrimental to the integrity of the Scenic Area. No reconstruction or expansion of a private or commercial building, including
(A) reconstruction of an existing building,
(B) construction of attached structural additions, not to exceed 100 per centum of the square footage of the original building, and
(C) construction of reasonable support development such as roads, parking, water and sewage systems shall be treated as detrimental to the integrity of the Scenic Area or as an incompatible development within the meaning of paragraph (2) of subsection (a) of this section.