A San Diego property described as having an accessory dwelling unit requires a disciplined review before a buyer relies on the unit or a seller markets its benefits. The term “ADU” does not, by itself, establish that the structure was approved, completed in accordance with approved plans, insured for its current use, or acceptable to a particular lender. It also does not establish a specific rental amount or contribution to appraised value.
The appropriate review begins with the governing jurisdiction and continues through permit records, inspections, physical condition, utilities, access, leases, insurance, financing, taxes, and operating costs. California’s Accessory Dwelling Unit Handbook provides the statewide framework, but local procedures and property-specific conditions remain material. The following checklist is intended to help San Diego buyers and sellers organize that review in 2026.
1. Confirm the governing jurisdiction before reviewing ADU requirements
“San Diego” can refer to the City of San Diego, another incorporated city within San Diego County, or an unincorporated area administered by the County. A mailing address, ZIP code, or marketing description does not reliably identify the land-use authority. Confirm the parcel and jurisdiction through an official mapping or property-record source before applying any local checklist.
For property within the City of San Diego, consult the City’s current ADU and JADU permit guidance, zoning information, and permit-record systems. For property in an unincorporated area, use the County Planning & Development Services ADU guidance and the County’s jurisdiction and zoning resources. Property in another incorporated city must be reviewed under that city’s current requirements.
After confirming jurisdiction, identify the base zone and applicable overlays. Coastal, environmental, geologic, fire-hazard, easement, and other site conditions may affect the required review. State law establishes important baseline rules, but it does not eliminate every local or site-specific requirement.
For a neighborhood-specific example of integrating ADU representations into a broader property investigation, review Blum Realty Group’s City Heights buyer checklist.
2. Establish the unit’s exact permit and approval history
Obtain the assessor’s parcel number, legal address, permit or project numbers, approved plans, correction notices, inspection history, and evidence of final approval. Within the City of San Diego, OpenDSD permits searches for many projects and approvals, while the City’s Development Services records program explains how to request records that are not available through a single online search.
Permit terminology must be read carefully. An application that was created, submitted, approved, or issued is not necessarily a completed permit with final inspection approval. Confirm the current status and review the inspection entries. The City’s permit-record guidance notes that these records can help determine whether work required approval and whether the work was legally constructed and completed.
Compare the approved plans with existing conditions. Relevant differences may include unit dimensions, bedroom or bathroom count, kitchen configuration, doors, windows, utility equipment, fire separation, parking or access arrangements, and later additions. The absence of a result in one online database is not conclusive because records may be archived, stored in another system, indexed under a different identifier, or unavailable online.
3. Treat an unpermitted or converted space as unresolved
A converted garage, detached structure, lower-level space, or addition should not be represented as a permitted ADU unless the supporting records establish that status. If records are incomplete or the current configuration differs from the approved plans, obtain a written property-specific assessment from the responsible agency and advice from qualified construction, design, and legal professionals.
The City of San Diego has a program for certain ADUs and JADUs constructed without a building permit before January 1, 2020, but it is not a universal approval process. Eligibility depends on matters that include the construction date, location, site conditions, applicable overlays or easements, current safety conditions, and the work required to meet the applicable standards. The process can still require plans, supporting evidence, agency review, fees, inspections, and corrections.
A buyer should not base the purchase budget on an assumption that an existing space can be legalized. A seller should not advertise legalization as certain or describe a unit as permitted while the issue remains unresolved. If the transaction will proceed before the status is resolved, the contract, valuation, financing, insurance, and intended use should reflect that uncertainty.
4. Inspect the structure, utilities, and access
Permit records do not replace a physical inspection. The review should address the foundation, roof, drainage, moisture intrusion, electrical system, plumbing, water heating, heating and cooling, ventilation, smoke and carbon-monoxide alarms, emergency egress, fire separation, exterior stairs and guards, and any shared structural components. An inspection may identify items outside a general home inspector’s scope, requiring evaluation by an engineer, electrician, plumber, roofer, or other qualified specialist.
Utilities require separate documentation. Determine whether the ADU has separate or shared electric, gas, water, sewer, and communications service; whether the existing service capacity is appropriate; whether utility work appears on the approved plans; and who is responsible for each account and cost. Separate meters, independent shutoffs, dedicated service, and a particular billing arrangement should never be assumed.
Review practical and legal access. Confirm the route to the unit, required clearances, emergency access, address identification, parking or storage arrangements, and any gates, stairs, retaining walls, common areas, easements, or association restrictions affecting use. The City’s site-plan guidance illustrates why property lines, easements, rights-of-way, structures, and access features should be documented rather than estimated from a site visit.
5. Review leases and operating arrangements
If the ADU is occupied, obtain every lease, amendment, addendum, rent ledger, security-deposit record, notice, utility agreement, parking or storage agreement, and material tenant communication. Confirm which furnishings, appliances, exterior areas, laundry facilities, and services are included. Reconcile the documents with the seller’s disclosures and actual property conditions.
Do not assume that the unit will be delivered vacant, that a tenancy can be changed on a preferred schedule, or that a particular short-term or long-term rental use is permitted. Current state and local landlord-tenant, rental, licensing, and short-term-rental rules may apply. Property-specific legal advice may be appropriate before notices are issued, terms are changed, or income is represented.
A seller’s operating statement should distinguish actual collected rent from advertised, projected, or market rent. It should also identify vacancy, utilities paid by the owner, repairs, maintenance, landscaping, insurance, taxes, management, licensing, and reserves. A buyer can then test a realistic operating scenario instead of relying on gross rent alone.
6. Address insurance, financing, and appraisal before relying on income or value
Ask an insurance professional to review the exact property, structures, condition, occupancy, and intended use. Obtain a written quote or coverage determination rather than assuming the current policy will continue unchanged. The California Department of Insurance advises consumers to review the policy’s coverage, conditions, limitations, and exclusions and to compare the protection offered by available policies.
Financing treatment depends on the loan program and the property. A lender may require permit documentation, appraisal analysis, lease documentation, reserves, or other underwriting support. Some programs permit consideration of ADU rental income only under defined occupancy, documentation, appraisal, and calculation requirements. For example, Fannie Mae’s rental-income guidance imposes specific conditions rather than treating projected ADU rent as automatically available income.
An ADU also does not produce a guaranteed appraisal adjustment. Appraisers analyze the unit’s characteristics, reported permit and zoning status, condition, market acceptance, comparable evidence, and effect on the property’s marketability. Fannie Mae’s appraisal guidance requires the ADU to be described and its effect on value and marketability to be analyzed. Construction cost, advertised rent, and a seller’s estimate are not substitutes for that analysis.
7. Calculate taxes and operating costs from the property’s records
Review the current tax bill, supplemental assessments, construction history, and any outstanding assessments or fees. The California State Board of Equalization explains that qualifying new construction is generally assessable and that completed new construction or a change in ownership can result in a supplemental assessment. The exact result depends on the assessor’s records, timing, ownership event, and property facts.
Prepare a property-specific operating worksheet that includes utilities, insurance, property taxes, repairs, preventive maintenance, reserves, landscaping, shared-area costs, professional management if applicable, and anticipated capital work. If legalization, plan corrections, or deferred maintenance remains unresolved, obtain qualified estimates and maintain an appropriate contingency.
8. Seller premarketing checklist
- Confirm the parcel, governing jurisdiction, zoning, and relevant overlays.
- Collect permits, approved plans, correction notices, inspection history, and final approvals.
- Compare the approved plans with the existing structure and current use.
- Resolve material discrepancies or disclose unresolved issues accurately.
- Organize inspections, repairs, warranties, utility records, insurance information, and tax documents.
- Assemble leases, deposits, ledgers, notices, and operating statements.
- Separate actual historical income from projections and avoid guaranteed value or rent claims.
- Coordinate the listing description, photographs, disclosures, and supporting documents so they are consistent.
9. Buyer offer and investigation checklist
- Identify the intended use of the ADU and provide that use to the lender and insurer.
- Verify jurisdiction, permits, approved plans, inspection history, and final status independently.
- Inspect the structure and obtain specialist evaluations where indicated.
- Confirm utilities, service capacity, access, easements, parking, storage, and association restrictions.
- Review every tenancy and operating document with appropriate professional advice.
- Obtain property-specific financing, insurance, appraisal, tax, repair, and operating-cost information.
- Address unresolved permit or condition issues in the contract and decision-making process.
- Do not rely on projected rent, legalization, separate sale, or appraisal value unless the responsible professionals confirm the applicable facts.
Frequently Asked Questions
Does a listing description prove that a space is a permitted ADU?
No. Verify the governing jurisdiction, permit and approval numbers, approved plans, inspection history, and final status. Compare those records with the structure and use that exist at the property.
Can every unpermitted ADU in San Diego be legalized?
No. Eligibility and required corrections depend on the jurisdiction, construction date, site conditions, building condition, overlays, easements, and the applicable state and local process. Obtain a written property-specific determination from the responsible agency and qualified professionals.
Does an issued permit establish that the ADU received final approval?
Not necessarily. A permit can move through several statuses. Confirm the inspection record, required corrections, final approval, and whether the completed structure matches the approved plans.
Can a buyer automatically use projected ADU rent to qualify for financing?
No. Loan-program, occupancy, appraisal, lease, documentation, and underwriting requirements control. Submit the exact property and proposed income to the lender before relying on ADU rent in the purchase budget.
Does an ADU always add its construction cost to the property’s appraised value?
No. An appraiser analyzes the ADU, comparable market evidence, condition, utility, reported permit and zoning status, and marketability. Construction cost, advertised rent, and seller estimates do not guarantee a particular value conclusion.
Should a buyer assume that the ADU has separate utility meters?
No. Verify the approved utility design, current meters and service accounts, system capacity, connection responsibilities, and how actual costs are allocated under any tenancy.
What should a seller assemble before marketing a property with an ADU?
Assemble the jurisdiction and parcel information, permit and final-inspection records, approved plans, material repair and inspection records, utility information, leases and deposits, insurance information, tax records, warranties, and any association documents affecting the unit.
Can an ADU be sold separately from the primary residence?
Do not assume that it can. Separate conveyance requires a jurisdiction-authorized process and may involve condominium mapping, title, lender, inspection, utility, covenant, and other requirements. Verify the current program and the exact property’s eligibility before advertising separate-sale potential.
Blum Realty Group can help buyers organize a property investigation and help sellers prepare a consistent premarketing record. Review the firm’s buyer representation, home-selling services, home-loan information, and contact options.
This article provides general real-estate information as of August 16, 2026. It is not legal, tax, lending, insurance, appraisal, engineering, construction, or land-use advice. Requirements and property conditions vary. Confirm current rules and the exact property with the responsible government agency and qualified professionals before acting.