For non-residential (i.e., commercial) projects, go to petaluma.opencounter.com. This online tool will ask questions and, based on your answers, give you a list of permits you might need and an estimate of fees.
For residential projects (i.e., house and yard), check the list below and read the linked documents.
Building Division: Building Permit Checklist
Planning Division:
Special Events: Permits are required for special events including parades, athletic events and block parties that take place on a city street, sidewalk, or city-owned land. Download the permit form here.
Sprinklers: Sprinklers must be installed on all new residential construction and in remodels/additions that increase square footage. Read more here.