The 10 Steps to an ADU Permit
Identify the Correct Permitting Jurisdiction
Do not assume a San Diego mailing address means the City issues the permit. The County's ADU program applies to unincorporated areas, and incorporated cities (Chula Vista, El Cajon, Encinitas, Escondido, La Mesa, National City, Oceanside, Poway, San Marcos, Santee, Vista) run their own systems. Use the address and Assessor's Parcel Number to confirm jurisdiction, then use the City's Zoning and Parcel Information Portal for a City property. Designing under the wrong agency's checklist can require substantial rework.
Research the Property Before Designing
A permit application is only as accurate as its site information. Before selecting a floor plan, verify:
- legal lot status and APN; base zoning and planned-district regulations;
- Coastal, Parking Impact, Transit, Historical, and other overlay zones;
- Very High Fire Hazard Severity Zone status and emergency access;
- environmentally sensitive lands, steep slopes, or drainage constraints;
- recorded easements, utility locations, and property lines;
- legal permit history of the home, garage, and accessory structures;
- water/sewer/septic feasibility and electrical service capacity.
A fence, hedge, or old concrete edge is not reliable evidence of a property line — a survey may be needed when the unit sits close to a setback or an easement may conflict.
Choose the ADU Type and Approval Path
A detached ADU generally needs a complete site-specific plan package (the City defines a standard ADU as up to 1,200 sq. ft.). An attached ADU must coordinate the existing structure, fire separation, foundation, roof, and utilities. A conversion reduces new envelope work but must still document the existing structure for code compliance. A JADU (up to 500 sq. ft.) has different kitchen, sanitation, and ownership rules and requires a recorded Junior Unit Agreement before issuance. Preapproved plans can shorten review — the City accepts specified plans from the County, Chula Vista, and Encinitas and gives them a 30-day review — but they still must meet Municipal Code development regulations and site adaptation.
Create a Coordinated Plan Set
The plans must show both the dwelling and how it fits the property — typically a cover sheet and code info, existing/proposed site plans, floor and roof plans, elevations, sections, door/window schedules, foundation and framing plans, structural details and calculations, MEP information, utility routing, Title 24 energy documentation, and stormwater information (plus grading, landscape, or fire information when triggered). Coordinate disciplines before submittal: a floor plan can look complete while the structural grid conflicts with windows, the panel is undersized, or a sewer route crosses a footing. Choose a team that will stay responsible for plan-check responses.
Assemble the City Submittal Package
For Group R-3 ADU projects, the City's current housing-project guidance identifies these initial items:
- Building construction plans, including Title 24 energy documentation, historical-resource information when applicable, site-plan package, and architectural, structural, and landscaping sheets;
- structural calculations and truss calculations;
- Declaration of Eligibility (Form DS-4107);
- Storm Water Requirements Applicability Checklist (Form DS-560);
- Water Meter Data Card (Form DS-16).
This is a general list, not a promise that every project needs only those items — grading, geotechnical, fire, coastal, utilities, or historical review can add documentation. Compare the package to the current checklist sheet by sheet and keep addresses, dimensions, floor areas, and revision dates consistent across every form and drawing.
Submit the Permit Application
City Development Services accepts applications through its digital process. Group R-3 residential projects generally use a Combination Building Permit; other configurations can use a Building Permit (Information Bulletin 125 helps identify the type). The normal sequence: create the applicant account; enter property and project information; describe the scope accurately; upload the plan set, calculations, and forms per the City's file rules; submit for intake or completeness screening; correct intake deficiencies if requested; and pay the invoiced plan-check fees so review can begin. For an unincorporated property, follow County Planning & Development Services submittal steps instead.
Understand the 2026 Review Deadlines
California's 2026 rules added a clearer completeness step: the current HCD ADU Handbook explains that an agency must determine whether an ADU or JADU application is complete and give written notice within 15 business days. For a lot with an existing dwelling, state law generally requires the agency to approve or deny a completed ADU application within 60 days. These do not mean a construction-ready permit arrives 60 days after hiring a designer — the clock excludes pre-application design, an incomplete package must first be cured, and applicant response time, outside agencies, fees, and issuance are separate. Use the City's live permit-processing timeline for current queue information.
Respond to Plan-Check Comments as One Package
Review may cover building, structural, zoning, fire, water and sewer, stormwater, transportation, landscape, or historical issues. A strong response includes a written reply addressing every comment in order, the sheet/detail where each revision appears, revised calculations and forms, coordinated updates across all disciplines, required change notation (clouds/revision marks), and a complete resubmittal per the agency's upload instructions. Do not answer one comment by creating a conflict elsewhere — moving a wall can affect structural, energy, windows, plumbing, floor area, and elevations, so one person should control the full revision set.
Complete Issuance and Pay Final Fees
Plan approval and permit issuance are related but separate. After the disciplines approve the plans, the City may require final documents before stamping — such as the Project Contacts Form (DS-345), Owner-Builder Verification (DS-3042) when applicable, proof of school-fee compliance, and a Waste Management Form for qualifying projects. The City then generates an issuance invoice that can include inspection, addressing, recordation, and surcharge fees. Construction should not begin merely because plan comments are resolved — wait until the permit is formally issued.
Build to the Approved Plans and Pass Inspections
An issued permit authorizes construction; it is not final approval to occupy the unit. Keep stamped plans on-site and schedule inspections at the required stages — footing and foundation, underground utilities, slab or underfloor, framing, roof and weather protection, rough MEP, fire sprinkler when required, insulation and energy measures, drywall or lath, deferred systems like solar, and final approvals. Do not cover work before its inspection, and ask whether a material deviation from the approved plans must be reviewed before proceeding. Obtain final approval and any certificate before the ADU is occupied or rented.
Common Reasons ADU Plans Receive Corrections
Corrections are normal — the goal is not "zero comments" but preventing avoidable ones. Frequent triggers include:
- Property lines or setbacks not clearly documented.
- Existing structures do not match City or County records.
- Floor-area calculations differ between sheets.
- Utility routes and meter information are incomplete.
- Structural plans do not match architectural plans.
- Title 24 documents use a different window, wall, or mechanical specification.
- Fire separation, access, or opening protection is unresolved.
- Stormwater, grading, or drainage information is missing.
- A Coastal, historical, fire-hazard, or environmental overlay was overlooked.
- Plan files, forms, or signatures do not follow submittal requirements.
Seven Mistakes That Delay San Diego ADU Permits
A design can fail because of an easement, fire access, sewer route, slope, or overlay that was visible during early due diligence.
City, unincorporated County, and incorporated cities use different processes. Confirm the authority before ordering plans.
Standard plans still require property-specific adaptation and review. Accepted preapproved plans get a 30-day review — they do not bypass it.
A survey or authoritative property information may be needed when the ADU is close to a setback or easement.
Different floor areas, window schedules, structural grids, or utility layouts lead reviewers to ask which version controls.
Sewer elevation, water capacity, panel capacity, and service routes can force design changes. Evaluate them while the layout is flexible.
The state decision period starts with a completed application under specified conditions — design, screening, revisions, issuance, and construction add time.
Special Situations That Can Change the Permit Path
Coastal Overlay Zone
The City says a Coastal Development Permit is required for ADUs and JADUs in the Coastal Overlay Zone when the unit is not completely contained within the existing primary structure, increases habitable area, or converts non-habitable space. Specific processing and certified regulations apply — check current coastal guidance rather than assuming statewide streamlining eliminates coastal review.
Very High Fire Hazard Severity Zone
Fire access, water supply, building separation, openings, materials, sprinklers, and evacuation conditions can affect the design, and the City's Bonus ADU program has additional fire-hazard restrictions. Confirm requirements early, especially on canyon-edge, hillside, or limited-access properties.
Older or Historically Significant Property
The City's housing submittal guidance requests historical-resource information when a structure is older than 45 years, and a property in a historic district or involving a potentially historic building may need additional review even when the ADU itself is ministerial.
Septic Systems and Unpermitted Existing Units
An unincorporated property without public sewer may require onsite-wastewater review, where bedroom count, reserve area, and soil conditions control feasibility. And do not blindly use the new-construction process to legalize an older unit — City Information Bulletin 242 describes a streamlined retroactive-permit program for qualifying ADUs or JADUs built without a permit before January 1, 2020, with property-specific eligibility and correction requirements.
Should You Apply Yourself or Use a Design-Build Contractor?
A homeowner may coordinate designers, engineers, consultants, permit responses, and contractors separately — workable when the scope is simple and the owner has time to manage technical documents and deadlines. A design-build team places feasibility, design, engineering, estimating, permitting, and construction under one workflow. Before hiring, ask:
- Who confirms zoning, overlays, easements, and permit history?
- Who prepares and stamps each part of the plan set?
- Are survey, soils, Title 24, and utility coordination included?
- Who uploads the application and pays fees on the owner's behalf?
- How many correction cycles are included in the design agreement?
- Who tracks agency comments and controls revised plans?
- Are permit and outside-agency fees included or paid directly by the owner?
- Who handles construction changes and inspection corrections, and which services are excluded?
For broader design and construction budgeting, see our ADU building requirements & costs in San Diego guide, and explore our ADU construction services.
ADU Permit Checklist for San Diego Homeowners
- Correct permitting jurisdiction confirmed.
- Property address, Assessor's Parcel Number, legal lot, and existing permit records.
- Zoning and overlay research complete.
- ADU type, size, and use defined.
- Property lines, setbacks, easements, and utility routes documented.
- Site plan coordinated with actual conditions.
- Architectural and structural sheets complete; structural and truss calculations included when required.
- Title 24 energy documentation coordinated.
- Water-meter, sewer, and stormwater information addressed.
- Historical, coastal, fire, grading, and landscape items addressed when triggered.
- Application forms use consistent project information.
- Plan-check fees budgeted; person responsible for correction responses identified.
- Permit-issuance forms, final fees, and inspection/closeout responsibilities assigned.
Start Your ADU Permit Process With a Clear Plan
Getting an ADU permit in San Diego is easier when feasibility, design, engineering, utilities, and agency requirements are coordinated before you apply. First Choice Home Builders can evaluate your property, coordinate the permit process, and carry the approved design through construction.
Frequently Asked Questions
Do I need a permit to build an ADU in San Diego?
Yes. The City of San Diego states that a Building Permit is required to create an ADU or JADU and that there are no exemptions from that permit requirement. The appropriate permit and related reviews depend on the jurisdiction, property, and project scope.
How long does it take to get an ADU permit in San Diego in 2026?
California law generally gives the agency 15 business days to determine whether an application is complete and 60 days to approve or deny a completed ADU application on a lot with an existing dwelling. City-accepted preapproved plans currently receive a 30-day review. Total elapsed time can be longer because design, incomplete items, applicant response, outside agencies, fees, and issuance are separate.
Can I submit ADU plans myself?
An owner may act as the applicant, but the plans, calculations, and professional stamps still must meet the agency's requirements and California licensing laws. Confirm who will prepare structural, energy, civil, survey, or geotechnical work and who will answer plan-check comments before deciding.
Are preapproved ADU plans already permitted?
No. They are preapproved as repeatable building designs, not approved for a specific parcel. The site plan, setbacks, foundation conditions, utilities, energy documents, and local development rules still require project-specific work and agency review.
How much is an ADU permit in San Diego?
There is no universal fee. Plan-check, inspection, addressing, utility, school, fire, coastal, grading, impact, and other charges depend on jurisdiction, size, and scope. Request an estimate using current plans and the current fee schedule, and do not confuse an impact-fee exemption with exemption from all permit costs.
Do garage-conversion ADUs need permits?
Yes. A conversion changes the space to a dwelling and must be reviewed for residential building, fire, energy, ventilation, sanitation, and safety requirements. Existing unpermitted work can add documentation or correction needs.
Does an ADU need parking in the City of San Diego?
The City's current ADU page says parking is generally not required for new ADUs, with a limited exception involving certain garage conversions in the Beach Impact area outside a transit priority area. Affordable and Bonus ADUs can have separate parking rules — verify the address and current overlay status.
Can I use a San Diego ADU as a short-term rental?
The City currently states that an ADU or JADU may not be leased for fewer than 31 consecutive days. Other jurisdictions may phrase their local rules differently, so check the agency that governs the property.
Can I legalize an ADU that was built without permits?
Possibly. The City has a streamlined retroactive-permitting program for qualifying units built before January 1, 2020 under AB 2533. The unit may still require plans, fees, inspections, and health-and-safety corrections, and units outside the program follow another path.