ADU Feasibility Checklist | Zoning Guide by Building Club

Check if your property is in a residential zone that permits ADUsCriticalADUs are typically allowed in single-family and sometimes multi-family residential zones. Look up your zoning designation on the city or county zoning map.
Verify that ADUs are explicitly allowed in your zoning districtCriticalEven within residential zones, ADU permissions vary. Check whether ADUs are allowed by right or require a conditional use permit.
Check if your state has an ADU law that preempts local restrictionsStates like California, Oregon, and Washington have passed laws that override local barriers to ADU construction, potentially making approval easier.
Check for overlay district restrictions that may affect ADU constructionHistoric, environmental, or other overlay zones may impose additional design standards or prohibit ADUs entirely.

Measure your lot size to confirm it meets the minimum for an ADUSome jurisdictions require a minimum lot size before an ADU can be added. Check your local zoning code for the specific threshold.
Check rear and side setback requirements for ADU placementADUs often have their own setback rules, which may differ from the primary dwelling. Rear setbacks of 4-5 feet are common in many jurisdictions.
Verify that utility connections (water, sewer, electric) are accessible for the ADUDetermine whether existing utility lines can serve the ADU or if new connections are needed, as this affects both cost and feasibility.
Check for easements that could restrict ADU placementCriticalUtility, drainage, or access easements on your property may limit where an ADU can be built.

Calculate the maximum ADU size allowed on your lotMaximum ADU size is often defined as a percentage of the primary dwelling size or a fixed square footage cap, whichever is smaller.
Check height limits for detached ADUsHeight restrictions for ADUs are often lower than for primary dwellings, typically ranging from 16 to 25 feet depending on the jurisdiction.
Determine which ADU type is feasible (detached, attached, or conversion)Consider whether a detached unit, an addition to your home, or a garage conversion best fits your lot, budget, and local regulations.
Check parking requirements for the ADUSome jurisdictions require one additional off-street parking space for an ADU, while others have eliminated ADU parking requirements entirely.

Estimate total permit and impact fee costs for your ADU projectPermit fees, impact fees, and utility connection charges can range from a few thousand dollars to tens of thousands depending on your jurisdiction.
Check the expected permit review and approval timelineADU permit timelines vary widely. Some jurisdictions offer expedited review, while others may take several months.
Verify utility connection fees for a new ADUWater, sewer, and electrical connection fees can be a significant cost. Some jurisdictions waive or reduce these fees for ADUs.

Review HOA CC&Rs for any restrictions on ADU constructionCriticalSome HOAs prohibit or restrict ADUs, though in certain states HOA restrictions on ADUs have been limited by law.
Check deed restrictions that may prohibit additional dwelling unitsPrivate deed covenants may restrict the number of dwellings on a property regardless of what zoning allows.