About ADU Project Planner
Clearer information for better ADU decisions.
ADU Project Planner is an independent research and education website focused on California ADU planning. We turn housing rules, source documents and project questions into practical planning steps before homeowners commit major money.
Who maintains the research
Research should be useful, traceable and honest about its limits.
Why this site exists
The hardest part often comes before construction.
Homeowners encounter conflicting cost estimates, technical zoning language, rapidly changing local rules, and advice shaped by someone trying to sell a design or construction service. It can be difficult to know which question to ask first.
We organize that complexity into a practical planning sequence: define the household goal, screen the property, verify current rules, establish a complete budget, compare delivery options, and prepare for professional conversations.
Who we serve
Built around real homeowner goals.
Plan space around people.
For households considering an ADU for parents, adult children, caregiving or aging in place.
Test the assumptions first.
For owners evaluating long-term rental use, operating assumptions and local restrictions before committing capital.
Make the property file useful.
For homeowners comparing cost, financing, long-term utility and project risk before speaking with professionals.
Our editorial standard
Useful information must also be checkable.
Every guide should help a homeowner understand not only the answer, but where it came from and what still needs local confirmation.
Start with primary sources
California HCD guidance, state law, municipal code, planning departments, permit portals and official fee or program materials come first.
Show dates and assumptions
Guides state jurisdiction and review date. Calculators explain inputs, exclusions and uncertainty instead of presenting estimates as guarantees.
Separate fact from judgment
When an answer depends on property conditions, local interpretation or professional expertise, that limitation is stated explicitly.
Independence
Not a sales funnel disguised as research.
ADU Project Planner is designed as an educational resource, not a substitute for a planning department, architect, engineer, attorney, tax adviser, lender or licensed contractor. Commercial relationships or affiliate links should be clearly disclosed.
Accuracy
Rules change. Good research keeps moving.
Agencies revise guidance and every property has different constraints. Readers should verify important decisions locally. Corrections and updated source information are welcome through the Contact page.
Start with your property—not a sales pitch.
Use the planning path to organize the questions that determine feasibility, cost and next steps.