Homeowners often hear that ADUs are allowed by right in California, so they expect permitting to feel automatic. In reality, local jurisdictions still review ADU permit applications carefully. The difference is not whether your project is reviewed, but how it is reviewed. Most ADUs qualify for ministerial approval, which means the city or county must base its decision on objective standards rather than discretionary opinions. Even so, reviewers still verify compliance with zoning, building code, energy requirements, and site conditions.

Understanding how local jurisdictions review ADU permits helps homeowners plan more confidently and reduce delays. It also explains why the same ADU design might move quickly in one place and require more revisions in another. Santa Cruz, San Jose, San Francisco, Sacramento, Santa Rosa County, San Luis Obispo County, Santa Barbara, Los Angeles and LA County, Orange County, and San Diego all follow similar building code principles, but they each have different intake workflows, portal systems, reviewer staffing patterns, and local standards that shape the experience.

This guide explains the typical review sequence, what each reviewer is looking for, and how homeowners can avoid the most common issues. It includes a strong focus on San Jose and nearby communities like Campbell, Palo Alto, and Redwood City, where ADU demand is high and documentation quality makes a big difference.

Ministerial Review Versus Discretionary Review

Most ADU applications are processed ministerially. Ministerial review means the application is checked against objective rules such as setbacks, height limits, lot coverage, fire separation, and energy compliance. If the plans meet the standards, the jurisdiction should approve the permit without hearings or subjective judgment.

Discretionary review is different. It involves broader decision making, public input, or policy judgment. California ADU laws limit discretionary review for ADUs, but some sites can still trigger special processes, such as historic districts, coastal zones, or unusual site constraints. Even in those cases, local jurisdictions generally focus on objective compliance and required findings rather than personal preference.

For homeowners, the takeaway is simple. A ministerial ADU still needs a complete and code compliant plan set. The faster you can prove compliance, the faster the permit can move through the system.

Stage One: Intake and Completeness Check

Before any technical review begins, most jurisdictions run an intake or completeness check. This stage confirms that the application includes the required documents and forms. Many delays occur here because homeowners assume the plans alone are enough. In most cases, the jurisdiction also needs a title sheet, site plan, floor plan, elevations, structural information, energy documentation, and forms that confirm ownership and authorization.

In high volume jurisdictions like San Jose and Los Angeles, completeness checks can be strict and checklist driven. In smaller jurisdictions, the check may feel more flexible, but missing documents still stop the process. Completeness is not about approval. It is about ensuring the application is reviewable.

What Reviewers Want to See at Intake

Reviewers want clarity of scope. Is this a detached ADU, attached ADU, garage conversion, or interior conversion. They want to see the proposed square footage, the location of the ADU on the site, and the basic systems approach. If the package is missing core drawings or contains conflicting information, it may be returned for resubmittal before plan check begins.

Stage Two: Planning and Zoning Review

Planning review verifies zoning compliance. This includes setbacks, height limits, lot coverage, separation from other structures, access paths, and local standards related to privacy and outdoor space. Many jurisdictions also check parking rules, though state exemptions often reduce parking requirements for ADUs. The planning reviewer is not judging whether your ADU is a good idea. They are verifying that it fits legally on the property.

In San Jose, planning review often relies heavily on the site plan. Clear dimensions and consistent labeling reduce follow up questions. In Santa Cruz and San Luis Obispo County, planning review may also focus on drainage, grading, or coastal related considerations. In San Francisco, conversions often require careful definition of what space is being converted and how access is provided.

Planning comments are usually resolved by updating the site plan, adding notes, or clarifying measurements. When homeowners provide vague drawings, reviewers tend to issue more comments because they cannot verify compliance.

Stage Three: Building and Safety Review

Building review focuses on life safety and construction standards. This includes structural design, fire separation, means of egress, stair requirements, ceiling heights, smoke and carbon monoxide alarms, ventilation, and accessibility related standards. Even small ADUs must function as safe dwellings, and the building reviewer is responsible for verifying that the plans meet code requirements.

Detached ADUs often receive comments related to foundations, framing details, shear walls, and mechanical ventilation. Conversion ADUs often receive comments related to existing conditions, insulation, egress, and fire rated assemblies. In older building contexts like San Francisco and parts of Los Angeles, reviewers may require additional details because existing conditions are less predictable.

Stage Four: Structural Review and Calculations

Structural review may be handled by a separate reviewer or combined with building review, depending on the jurisdiction. The structural reviewer checks that loads are carried properly, that framing plans are complete, and that seismic requirements are addressed. Missing details often trigger plan check comments that can add time, especially if the project relies on generic notes rather than specific connection details.

In Santa Rosa County and Sacramento, structural review often moves quickly when calculations are clear and coordinated. In coastal regions like Santa Cruz, site conditions may influence foundations and anchorage details. In San Jose, structural review tends to be predictable when drawings are complete but can become slower if architectural and structural sheets conflict.

Stage Five: Energy Review and Title 24 Compliance

Energy review verifies that the ADU meets California energy requirements. The most common issue is mismatch between drawings and energy documents. For example, the plans may show a different window type, insulation value, or HVAC system than what is listed on the energy forms. Even small inconsistencies can trigger corrections because the jurisdiction needs a clear compliance record.

This shows up everywhere, but it is especially common in fast moving review environments like San Jose, San Diego, and Los Angeles, where reviewers use checklists and reject sets that do not align. A last minute design change that is not reflected across documents can lead to a resubmittal.

Stage Six: Fire, Public Works, and Utility Coordination

Depending on the site and local process, ADU permits may also involve fire review, public works review, and coordination with utility providers. Fire review may check access routes, hydrant proximity, and defensible space considerations in certain areas. Public works may review driveway work, curb cuts, drainage, or right of way impacts. Utilities may require separate approvals for electrical upgrades or sewer connections.

In hillside or higher fire risk areas of Los Angeles and San Diego, fire access can be a major factor. In Santa Cruz and San Luis Obispo County, drainage considerations often shape public works requirements. In San Francisco, utility routing through older sites can require careful planning. These steps are not meant to block ADUs. They are meant to protect safety and infrastructure.

San Jose Focus: Why Documentation Quality Matters

San Jose processes a high volume of ADU applications, and that volume makes clarity critical. Neighborhoods like Willow Glen, Almaden Valley, Evergreen, Cambrian Park, and Berryessa have different lot patterns and privacy conditions, but the review process consistently rewards clean site plans, consistent plan sets, and complete documents.

Nearby cities like Campbell, Palo Alto, and Redwood City apply the same statewide ADU framework but may emphasize different local details such as privacy window placement, exterior design standards, or conversion documentation. Treat each jurisdiction as its own process, even when the design is similar.

How Homeowners Can Reduce Review Cycles

The most effective way to reduce review cycles is to submit a complete, coordinated plan set and respond to comments with precision. Use a comment by comment response letter. Update all sheets consistently. Cross check architectural, structural, and energy documents before resubmittal. When reviewers see a clean and consistent package, they can approve faster because they spend less time interpreting intent.

Factory built and modular ADUs can also support smoother review because unit dimensions and systems are resolved earlier. This helps reduce late stage changes that cause mismatches in energy and structural documentation. Site work still requires careful planning, but predictable unit design can simplify coordination.

Closing Perspective

Local jurisdictions review ADU permit applications through a structured sequence: intake, planning, building, structural, energy, and sometimes fire and public works. The process is designed to verify compliance with objective standards, not to create unnecessary barriers. When homeowners understand what each reviewer needs and prepare a coordinated set, approvals become faster and more predictable.

Across Santa Cruz, San Jose, San Francisco, Sacramento, Santa Rosa County, San Luis Obispo County, Santa Barbara, Los Angeles and LA County, Orange County, and San Diego, the same principle holds. Clear documentation reduces questions. A strong site plan anchors zoning review. Coordinated energy and structural details reduce rechecks. With the right preparation, local review becomes a manageable pathway to a finished ADU that adds real long term value.