Informational only — not legal advice.

ADU Explorer is an editorial field guide. We work to keep our data accurate, but every project is different and every city's rulebook drifts. Use this as a starting point — not a substitute for talking to the people who say yes or no.

In detail

What this site is

ADU Explorer publishes researched, editorial summaries of California ADU law, city-by-city permit fees and timelines, and an interactive cost estimator. Our goal is to help homeowners walk into their first contractor conversation with a working mental model.

What this site is not

This site does not provide:

Legal advice. Statutory summaries are not a substitute for a licensed California attorney's review of your specific situation.
Financial advice. Cost estimates, rent projections, and uplift figures are based on aggregated market data — not appraisals or tax forecasts.
An engineering opinion. Feasibility on your specific lot depends on soils, slope, easements, overlays, and existing structures we can't see.
A guarantee of permit approval. Even a perfectly compliant application can be delayed, conditioned, or denied. Plan-check is human.

Verify with your city

Every city dossier links to the official planning portal. Before you commit time or money, open that portal and re-check the fee schedule and processing windows. Fees drift annually; rules occasionally change mid-year.

Cost figures are estimates

Cost bands reflect 2026 LA-area pricing for typical ADU projects. Your actual cost depends on contractor selection, finish choices, site conditions, financing, and timing. Treat our numbers as a project envelope — not a bid.

Liability

To the maximum extent permitted by law, ADU Explorer and its operators disclaim all liability for losses arising from reliance on this site's content.

Corrections

If something looks wrong, email us. We update city data quarterly and fast-track reported errors.