Existing records
Identify the legal use and permitted status of the main home, garage, additions, and other structures.
Field note 01 · Requirements
Fullerton ADU requirements start with current sources.
Read statewide ADU law beside Fullerton’s current pages, the property record, and the proposed work. One old bulletin cannot answer every address.
01 · Code baseline
Confirm which standards govern the submission.
Fullerton’s current building-codes page states that the 2025 California codes and Fullerton amendments apply to projects submitted on or after January 1, 2026. Check the current City ADU page and California HCD handbook alongside the code edition.
Source checkpoint
Older City documents can explain background, but they should not silently replace the current code and live instructions.
02 · Property read
Requirements become real on the site plan.
Placement
Map lot lines, structures, easements, grade, access, trees, and likely fire and construction paths.
Utilities
Trace likely sewer, water, electrical, drainage, and meter work before calling a layout settled.
Unit program
Define intended use, target size, privacy, parking conditions, accessibility goals, and storage needs.
03 · Pre-design questions
Resolve the high-impact unknowns first.
Which ADU type fits?
Detached, attached, conversion, and junior units interact differently with existing construction and daily use.
What needs verification?
List every record, dimension, utility route, and agency answer the concept currently assumes.
What belongs in the package?
Use the City’s current forms and bulletin library to identify project-specific drawings and supporting documents.
04 · Property facts
Do not let a general rule replace the site review.
Two Fullerton lots on the same street can differ in dimensions, structures, easements, slope, fire access, utilities, title conditions, and permit history. The current statewide baseline and local process still have to be applied to the individual property.
Start a record of each fact, its source, the date checked, and the person responsible for the next answer. Keep measurements separate from estimates. Keep private association review separate from City permitting. Keep a neighboring approval separate from a determination for your address.
When the concept changes, revisit the requirements affected by size, height, placement, openings, parking conditions, fire access, and the chosen ADU type. That discipline prevents an old assumption from moving unnoticed into engineering and construction pricing.
Move the project forward
Know what the next decision needs to answer.
Call with the current plan, permit comments, or estimate. We will discuss the construction issue in front of you and what evidence is still missing.