E2/AS1 sets the limitations for Brick Veneer heights in Section 9.2.3 and Figure 73B . You can read this document here: E2/AS1 (part4)
It advises that brick veneers with timber framing shall have:
A maximum height of veneer above finished ground level of 7m;
A maximum height of 4m from the foundation;
A maximum height of 5.5m to the apex of a gabled area.
If the veneer is supported by a masonry structure, NZZS4229:2001 permits a veneer height of 6.0 for the wall and up to 10m in a gable area.
The Clay Brick and Paver Manufacturers Association have developed a combined 2 storey system for clay brick veneer- Design Note TB 1. Designers and Bricklayers should familiarise themselves with this document which you can read here: 2StoreyClayBrickVeneerConstruction- MadeEasy
You may also want to consider the following concrete brick 2Storeysolutions: