ADU Feasibility Checker
Check if your property qualifies for an ADU. Get instant results based on your city's current regulations, including size limits, setback requirements, and owner-occupancy rules.
How to Use the ADU Feasibility Checker
Using the ADU Feasibility Checker is straightforward. First, select your city from the search box. The tool covers the top 100 US cities by population, each with verified data sourced directly from municipal codes and planning department websites. Second, if your city uses formal zoning districts — which most cities do — select your zoning district from the dropdown. The tool automatically displays residential zoning districts for the selected city, so you only see zones relevant to ADU construction. If you are unsure of your property's zone, check your city's official zoning map or enter your address into your city's online GIS portal. Third, enter your lot dimensions in the width and depth fields. Lot size can affect feasibility in cities with minimum lot size requirements for ADU construction. Fourth, select the type of ADU you want to build: detached, attached, or Junior ADU (JADU). Each type has different size limits, setbacks, and eligibility rules. Fifth, click the Check Feasibility button to see your results. Results include the allowed or not allowed determination, maximum ADU size for your chosen type, setback requirements, estimated permit fees, typical permit timeline, and direct links to your city's permit portal and ADU rules page.
Understanding ADU Types
There are three primary types of ADUs recognized in most US jurisdictions, each with distinct characteristics and regulatory treatment. A detached ADU is a standalone structure physically separate from the main house. It can be a newly constructed backyard cottage, a converted detached garage, or a prefabricated unit placed on a permanent foundation. Detached ADUs typically have the most flexibility in terms of design but must meet setback requirements on all sides. Maximum sizes generally range from 400 to 1,200 square feet depending on the jurisdiction, with California capping detached ADUs at 1,200 square feet statewide. An attached ADU shares at least one wall with the primary dwelling. This includes additions, basement conversions, and ground-floor garage conversions that expand the footprint of the existing structure. Attached ADU sizes are often calculated as a percentage of the primary dwelling's square footage, commonly capped at 50 percent of the existing home up to a maximum. A Junior ADU (JADU) is a smaller unit — typically no more than 500 square feet — created within the existing footprint of a single-family home or its attached garage. JADUs require an interior connection to the primary dwelling in most jurisdictions and are subject to less restrictive permitting in states like California. Not all cities allow all three types, particularly JADUs, which are primarily a California regulatory concept. The feasibility checker shows only the rules applicable to your selected city and ADU type.
What Your Results Mean
The results panel gives you a complete snapshot of ADU feasibility for the city and configuration you selected. The allowed or not allowed badge tells you whether ADUs are currently permitted under the city's zoning code. Even in cities where ADUs are technically allowed, specific zone restrictions or deed restrictions may affect your individual property — always verify with your local planning department before making major decisions. The maximum ADU size field shows the largest unit you can legally build for your chosen ADU type, sourced from the city's current zoning code or state law. The setbacks section shows the minimum distances your ADU must maintain from the front, side, and rear property lines. These distances are often different from the setbacks that apply to the primary dwelling. The estimated permit fees field shows a total cost estimate based on the city's published fee schedule, including plan check fees, building permit fees, and applicable impact or school fees. Note that actual fees may vary based on project valuation, specific ADU size, and whether state-level fee exemptions apply. The permit timeline shows the typical processing time from application submission to permit issuance. All data displayed in the results is sourced from official municipal code documents, state government code sections, and city building department websites, with last-verified dates shown below the tool. Use the Next Steps links to visit your city's permit portal, read the full ADU rules page for your city, or check additional can-I-build guidance.
Source: PropertyZoned Research Team. Last verified April 6, 2026. View source