For all new buildings and additions you will have to show what you are planning to do about seismic restraint of the structure. In most cases we will receive drawings and schedules from a Registered Professional (structural engineer) that show all of the requirements.
It is not mandatory that you use a structural engineer as there are descriptions in the Building Code that explain what the requirement is.
The following documents may assist you with your design:
Seismic Design for Houses [PDF - 371 KB]
The Illustrated Guide for Seismic Design of Houses