Setbacks, lot coverage, height limits, state exemptions, permit timelines, and fees — explained in plain language, without the planning-department jargon.
Since 2020, California law has required cities and counties to approve ADU permits ministerially — without discretionary review — if the project meets objective state standards. Local governments cannot opt out.
Four categories of ADUs are exempt from local zoning requirements like lot coverage, floor-area ratio, open space, and front setbacks. These must be approved ministerially.
AB 68 and AB 881 require permits for ADUs and JADUs to be approved or denied within 60 days. If the jurisdiction fails to act, the permit is automatically approved.
Local development standards cannot prevent construction of at least an 800 sq ft ADU with 4-foot side and rear setbacks. Minimum lot size requirements cannot block an ADU.
California law prohibits owner-occupancy requirements for standard ADUs until 2025 and beyond. JADUs, however, do require owner occupancy of either the main home or the JADU.
Cities cannot require replacement parking when a garage is converted to an ADU or JADU, and many jurisdictions have eliminated parking minimums for ADUs entirely.
An ADU permit cannot be denied because the existing home or lot is legally non-conforming — unless the ADU itself creates a public health or safety threat.
These are the state-mandated standards that apply to most ADU projects. Local jurisdictions may be more permissive but cannot be more restrictive on these points.
Detached ADUs under 800 sq ft require no more than 4-foot side and rear setbacks. Attached ADUs and garage conversions have no additional setback requirement in most cases.
State Exempt ADUs are not counted toward lot coverage calculations. For non-exempt ADUs, jurisdictions cannot apply coverage limits that would prevent an 800 sq ft unit.
ADUs are permitted up to 16 feet in height as a matter of right, or 18 feet within half a mile of a major transit stop. Some jurisdictions allow up to 25 feet for two-story units.
Every residential property may have one ADU and one JADU. Multifamily properties may add multiple ADUs within existing structures or up to two detached ADUs.
Jurisdictions cannot impose a minimum lot size requirement that would preclude an ADU. Even small, legally created lots qualify for ADU development.
State Exempt ADUs are not subject to front setback requirements. For non-exempt ADUs, front setbacks generally match the underlying zoning but cannot block an 800 sq ft unit.
Government Code Section 66323 establishes four categories of ADUs that are exempt from local zoning standards — including lot coverage, FAR, open space, and front setbacks. These must be approved ministerially.
An ADU or JADU created within the existing walls of a single-family home or accessory structure, with no expansion beyond the existing footprint. No setbacks, no lot coverage impact, no additional parking.
An ADU built in the same location and to the same dimensions as an existing accessory structure being demolished. Allows a 150 sq ft addition for ingress, egress, and accessibility.
A detached ADU up to 800 sq ft with 4-foot side and rear setbacks and a maximum height of 16 feet. Exempt from lot coverage, FAR, open space, and front setback requirements.
A JADU up to 500 sq ft within an existing or proposed single-family residence, including an attached garage. Requires an efficiency kitchen and either a separate or shared bathroom.
Every ADU in California goes through the same ministerial review process. This is the sequence, with realistic timelines for each stage.
Permit and impact fees vary widely by jurisdiction. These are typical 2026 ranges from projects we have completed across California. Fees are paid directly to the jurisdiction at their published rates.
| ADU Type | Typical Permit Fees | Impact Fees | Notes |
|---|---|---|---|
| Junior ADU (JADU) | $1,500 – $4,000 | Usually exempt | Lowest fees; many cities waive impact fees entirely |
| Garage Conversion | $2,500 – $6,000 | $0 – $3,000 | Simplified review; no new structure |
| Attached ADU | $4,000 – $9,000 | $3,000 – $10,000 | Varies by square footage and jurisdiction |
| Detached ADU (under 750 sq ft) | $5,000 – $12,000 | $0 – $8,000 | Impact fees often reduced or waived under 750 sq ft |
| Detached ADU (750+ sq ft) | $8,000 – $18,000 | $8,000 – $30,000+ | Full impact fees apply in most jurisdictions |
The fees shown above are paid directly to your city or county. They are separate from our construction price and we do not add a markup to them. You pay the jurisdiction at their published rate, and we provide receipts for every fee. This is the fairest way to handle it — the same fee applies whether we build your ADU or a competitor does.
Only in narrow circumstances. Under California law, a jurisdiction must approve an ADU permit ministerially if it meets objective state standards. The city cannot deny it based on neighborhood character, aesthetic preferences, or subjective design review. Denial is only permitted if the ADU would create a specific, demonstrable public health or safety threat — for example, if the site cannot support the utility connection or the ADU would block emergency access. In practice, outright denials are rare; corrections and plan-check comments are common, but denials are not.
By law, 60 days. AB 68 and AB 881 require the jurisdiction to approve or deny an ADU permit within 60 days of receiving a complete application. If the city fails to act within that window, the permit is automatically approved. In practice, most simple ADU permits are issued in 30–60 days, while more complex projects (historic districts, hillside lots, commercial conversions) may take 90–150 days because of additional review layers.
A State Exempt ADU is one of four categories of ADUs defined in Government Code Section 66323 that are exempt from local zoning standards including lot coverage, floor-area ratio, open space, and front setbacks. These units must be approved ministerially and cannot be subject to discretionary design review. The four categories are: (1) an ADU or JADU within existing walls, (2) an ADU built in the same location and dimensions as an existing structure, (3) a detached ADU up to 800 sq ft with 4-foot setbacks, and (4) a JADU up to 500 sq ft within an existing home.
No. California law prohibits jurisdictions from requiring replacement parking when a garage, carport, or covered parking structure is demolished or converted to an ADU or JADU. This applies regardless of whether the parking was previously required by local ordinance. Some jurisdictions have attempted to impose replacement parking through local ordinances, but these have been struck down or overridden by state law in most cases.
Historic districts add complexity but do not automatically disqualify an ADU. Interior conversions are often permitted with minimal exterior changes, and many historic districts have design-review processes that are manageable if the exterior is preserved. Under state law, ministerial approval still applies to ADUs in historic districts, but the jurisdiction may impose objective design standards that protect historic character. We have completed projects in historic districts in Los Angeles, San Francisco, and Pasadena.
Yes. California law specifically prohibits jurisdictions from denying an ADU permit because the existing home or lot is legally non-conforming — for example, if the house was built before current setback requirements or sits on a lot that would not meet today's minimum size. The ADU itself must still meet applicable standards, but the non-conforming status of the existing structure cannot be used as a reason to deny the permit.
In most jurisdictions, no. Since ADUs are approved ministerially under state law, they do not require a separate zoning clearance, conditional use permit, or discretionary planning review. Some cities — including Oxnard and others — have explicitly eliminated the separate zoning clearance process for ADUs. Your building permit application is reviewed simultaneously by planning and building staff. We confirm the specific process for your jurisdiction during feasibility.
Impact fees are charges that jurisdictions levy to offset the cost of public infrastructure — schools, parks, roads, fire protection — that new development places on the community. For ADUs, California law limits how these fees can be applied. ADUs under 750 sq ft are exempt from most impact fees. For larger ADUs, fees must be proportional to the square footage of the primary residence, not the ADU itself. JADUs are typically exempt from impact fees entirely.
Send us the address. We will pull the zoning records, check the setbacks and lot coverage, confirm what your jurisdiction allows under current state law, and send a written feasibility report with realistic options.