The vertical datums presently used in Latin America refer to different sea levels and different epochs, they do not take care of the height and reference level variations with time, and in most of the countries, the vertical networks were processed without including the corresponding gravity reductions in the levelled heights. These datums present big discrepancies between neighbouring countries, they do not permit data exchange neither in continental nor in global scale, and they are not able to support practical height determination with GNSS techniques.

In contrast, the new SIRGAS vertical reference system shall:

The official recommendation of SIRGAS about the physical heights is to introduce normal heights; however, since some countries want to adopt orthometric heights, it was decided to define the new vertical reference system in terms of geopotential quantities (W₀ as a reference level and geopotential numbers as primary coordinates), and then, in the realization, each country can introduce the desired physical heights with their respective reference surface: the geoid or the quasigeoid.

The realization of the new SIRGAS vertical reference system corresponds to the SIRGAS2000 frame, it contains the stations of the SIRGAS95 reference frame, the principal tide gauges of each country, and some stations at the borders to connect the first order levelling networks between neighbouring countries. These stations refer to the SIRGAS system, shall be connected by spirit levelling with the reference tide gauges, and their geopotential numbers shall be known. Since the SIRGAS national densifications include an increasing number of permanent stations of the SIRGAS-CON network, some of them are also integrated into the vertical reference frame.

The activities related to the definition and realization of the new vertical reference system for SIRGAS are coordinated by the SIRGAS-WGIII: Vertical Datum.