Converting a garage into living space in Climate Zone 3 generally triggers a Title 24 CF1R report, because it creates new conditioned area.
Why conversions trigger Title 24
Garages are typically uninsulated and unconditioned, so a conversion almost always involves new insulation, windows, and HVAC — the elements Title 24 evaluates. Title 24 is a statewide California energy code. Climate Zone 3 does not have its own separate rules — the same statewide standards apply, with the energy budget calibrated to this zone's climate. Your project's exact requirements are determined when your specific address is modeled in CEC-approved compliance software.
See the statewide garage conversion Title 24 guide and our ADU service (many conversions become ADUs).