Unlike the proposed demolition proposed in the 1964 scheme, the 1972 development plan required the new building to be constructed entirely within the boundary of the existing site, while leaving space for future additions to the State Library of New South Wales. Added to this restraint the work of the Parliament needed to continue through the entire construction period.
The 1972 development plan differed from the 1964 demolition proposal in its requirement that the new building be constructed within the existing site boundaries, while reserving space for future expansions of the State Library of New South Wales.  This constraint was also coupled with the need to maintain Parliament's operations throughout the construction period.