Navigating San Diego's ADU Regulations: Tips for Homeowners

In San Diego, a single-family lot can have up to three ADUs by right: one detached ADU, one converted from existing home space, and one Junior ADU (JADU), limited to 500 sq. ft. and requiring owner occupancy. The Affordable ADU Bonus Program allows adding one affordable ADU plus one additional market-rate ADU, totaling up to five ADUs. Properties in Transit Priority Areas may qualify for even more ADUs if affordability requirements are met.

Multifamily properties in San Diego can build up to eight detached ADUs starting January 2025, matching the existing unit count. There’s no limit to ADUs created by converting non-livable spaces (garages, storage rooms, basements), provided building codes are met. The total ADUs allowed depend on property size, zoning, and building regulations.

In San Diego, the maximum size for an ADU depends on its type. Detached and attached ADUs can be up to 1,200 square feet, with a minimum size of 150 square feet. ADUs that are 800 square feet or smaller are exempt from lot coverage, floor area ratio (FAR), and open-space requirements. Junior ADUs (JADUs), created within existing space in the primary home, have a maximum size of 500 square feet and require owner occupancy but do not have parking requirements.

In San Diego, a detached ADU can be up to 1,200 square feet, with a minimum size of 150 square feet. ADUs of 800 square feet or smaller are exempt from lot coverage, floor area ratio (FAR), and open space requirements. The standard height limit for a detached ADU is 16 feet, allowing zero-foot side and rear setbacks. If the ADU exceeds 16 feet in height, including two-story structures, it must have a minimum four-foot side and rear setbacks and can be built up to the maximum height permitted by the underlying zoning, typically between 24 and 30 feet.

In San Diego, an attached ADU can be up to 1,200 square feet, with a minimum size of 150 square feet. The height limit for an attached ADU is generally up to 25 feet or must comply with the zoning regulations for the primary residence. Since attached ADUs are integrated into the main home’s structure, they must follow the same setback and design requirements as the primary dwelling.

In San Diego, detached ADUs are generally limited to 16 feet in height with zero-foot setbacks. If exceeding 16 feet, including two-story ADUs, they must maintain a minimum four-foot side and rear setback and can reach the maximum height allowed by zoning, typically ranging from 24 to 30 feet. Detached ADUs built above garages have specific limits: 21 feet maximum for flat roofs and up to 30 feet for sloped roofs. Attached ADUs must comply with the primary home’s zoning height limits.

Yes, two-story ADUs are permitted in San Diego. Detached two-story ADUs taller than 16 feet must maintain at least a four-foot setback from side and rear property lines when adjacent to residential properties, and their maximum height typically ranges between 24 and 30 feet, depending on zoning. ADUs built above garages have specific height limits: 21 feet for flat roofs and up to 30 feet for sloped roofs. Attached two-story ADUs follow the zoning height limits of the primary residence, generally up to 25 feet.

Roof decks are permitted on ADUs in San Diego but must comply with specific regulations. The overall height of the structure, including the deck, must remain within the allowable limits, which range from 16 to 30 feet depending on zoning. Roof decks cannot encroach into the required four-foot setbacks, and any railing exceeding 42 inches in height is included in the total structure height calculation. If the ADU is within five feet of the property line, fire-rated materials are required for safety. In some cases, privacy screening may also be necessary to minimize impacts on neighboring properties.

San Diego does not impose strict exterior design requirements for ADUs, but they are generally expected to complement the primary residence. There are no mandated materials, though commonly used options include stucco, wood siding, and fiber cement board. ADUs must adhere to zoning regulations related to setbacks, landscaping, and fire safety standards. While parking is not required for most ADUs, certain areas within the Coastal Zone may have specific parking requirements.

San Diego does not impose a specific limit on the number of bedrooms in an ADU, but all rooms must comply with the California Building Code. Each bedroom must be at least 70 square feet, and the overall ADU must be a minimum of 150 square feet. While there are no additional parking requirements based on the number of bedrooms, some Coastal Zones may have specific regulations. In a 1,200-square-foot ADU, up to three bedrooms can typically be accommodated, depending on the layout and design.

Yes, all ADUs in San Diego must have a kitchen. Full ADUs require a complete kitchen with a sink, stove or cooktop, countertops, cabinets, and refrigerator space. Junior ADUs (JADUs) need only an efficiency kitchen with a sink, basic electric cooking appliances, countertops, and cabinets, but no full stove or gas connection is required.

All ADUs in San Diego must have at least one full bathroom (toilet, sink, shower or bathtub). Half-baths are not sufficient. Junior ADUs (JADUs) may share the primary home’s bathroom but must meet building codes if they include their own. Bathrooms require water/sewer connections and ventilation via a code-compliant window or exhaust fan. Separate water meters typically aren’t required.

All ADUs in San Diego are required to have at least one full bathroom, which must include a toilet, sink, and either a shower or bathtub. Half-baths, which only contain a toilet and sink, are not sufficient for standalone ADUs. There is no minimum size requirement for the bathroom, but it must comply with California Building Code accessibility and space guidelines. Junior ADUs (JADUs) are not required to have their own bathroom and may share one with the primary residence, but if a JADU does include a bathroom, it must meet all plumbing and building code requirements. Bathrooms in ADUs must be connected to existing water and sewer lines, either through the primary home or independently, and a separate water meter is generally not required. Ventilation is mandatory, either through a window that meets code size requirements or an exhaust fan.

In San Diego, ADUs can be detached or attached, up to 1,200 sq. ft., with a full kitchen and bathroom, and don’t require owner occupancy. JADUs must be created from existing space in a single-family home, limited to 500 sq. ft., require an efficiency kitchen, can share a bathroom, and the owner must live on-site. Both require rentals of at least 31 days and generally don’t need additional parking.

In San Diego, detached ADUs up to 16 feet tall can have zero-foot side and rear setbacks. Those over 16 feet require four-foot setbacks from side and rear property lines adjacent to residential properties. Attached ADUs follow the primary home’s setbacks, while garage conversions and JADUs have no additional setbacks. ADUs within five feet of property lines require fire-rated materials, and detached ADUs must maintain at least six feet from other structures. Front-yard setbacks typically follow zoning rules, but state law may allow encroachment for ADUs up to 800 sq. ft. if necessary.

In San Diego, detached ADUs up to 16 feet tall can have zero-foot side and rear setbacks. Taller detached ADUs must have at least a four-foot side and rear setback next to residential properties. Attached ADUs follow the primary home’s setbacks, while garage conversions and JADUs require no additional setbacks. Structures within five feet of a property line must use fire-rated materials. Coastal Zone properties may have extra setback requirements.

In San Diego, a detached ADU must be at least six feet from any existing structures on the same lot to comply with fire safety codes. If the eave-to-eave distance between the ADU and another structure is less than 10 feet, fire-resistant materials and additional fire separation measures may be required. Attached ADUs, as well as garage conversions or ADUs built within an existing structure, do not require any separation since they are integrated into the primary dwelling. If an ADU is built above a garage or another existing structure, no additional spacing is necessary beyond standard building code requirements.

In San Diego, a detached ADU must be at least six feet from the main house to comply with zoning and fire safety regulations. If the eave-to-eave distance between the ADU and the primary residence is less than 10 feet, fire-rated construction, including fire-resistant walls, windows, and roofing, may be required. Attached ADUs and garage conversions do not require separation, as they are considered part of the primary structure. In some cases, property owners may apply for a variance to reduce the six-foot spacing requirement if lot constraints exist, but if an ADU is closer than five feet, additional fire-resistant materials will be required.

Yes, an ADU can be built in the front yard in San Diego, but it must comply with the front-yard setback requirements specific to the zoning district. Detached ADUs are allowed in the front yard as long as they adhere to the zoning setback rules, while attached ADUs must follow the front-yard setbacks of the primary home. If a garage located in the front yard is converted into an ADU, no additional setbacks are required. Junior ADUs, however, must be within the existing home and cannot be constructed as separate structures in the front yard. Under state law, if no other placement is possible, at least one ADU of up to 800 square feet is permitted to encroach into the front-yard setback.

Yes, all ADUs and Junior ADUs in San Diego require a building permit. The permitting process includes zoning verification, submitting architectural and engineering plans online, and city review within 60 days. Permit costs range from $5,000 to $15,000. ADUs up to 750 sq. ft. are exempt from most impact fees, and units up to 800 sq. ft. have certain zoning exemptions. Additional permits may be needed in Coastal or historic areas. Detached ADUs require solar panels, and fire sprinklers if the main home has them. Pre-approved plans can speed up approvals.

Yes, San Diego allows digital submission of ADU plans through the Development Services Department’s Digital Permit Portal, making the process more efficient and accessible. Applicants must prepare and upload required documents, including architectural drawings, structural plans, site plans, and Title 24 energy calculations. The city reviews submissions within 60 days, and any required corrections must be resubmitted online. Once approved, permits are issued digitally, allowing construction to begin after final fees are paid. While in-person submissions are still accepted, they are not required, and online applications are recommended for faster processing, easier tracking, and more streamlined communication with city officials.

A soils report is generally not required for constructing an ADU in San Diego, but exceptions exist based on site conditions and project scope. ADUs built on level ground with stable soil, garage conversions, JADUs, and small detached units under 750 square feet on conventional foundations typically do not need a soils report. However, if the property is on a steep slope, in a geohazard or flood-prone area, or has expansive or unstable soil, the city may require a geotechnical report to assess foundation stability. Larger ADUs over 1,200 square feet or two-story structures may also require a soils report to determine load-bearing capacity. Homeowners should consult the San Diego Development Services Department or a geotechnical expert to confirm whether a report is necessary for their specific project.

Yes, a Coastal Development Permit (CDP) is required for ADUs in San Diego’s Coastal Zone, though some ADUs qualify for exemptions. Exemptions often apply outside the Beach Impact Area, for garage conversions, or on already developed lots without sensitive land impacts. Recent rules allow San Diego to approve many Coastal Zone ADUs locally without higher-level appeals. Homeowners should verify CDP requirements through city zoning resources before applying.

San Diego generally doesn’t require Building Verification Surveys (BVS) for ADUs, except in special cases. A survey might be necessary if property lines are unclear, the ADU is near setback limits, within a Coastal Zone or historic district, involves hillside or steep slope construction, or if fire safety rules apply near property boundaries. Homeowners should consult the Development Services Department or a licensed surveyor if uncertain.

In San Diego, stormwater mitigation is generally not required specifically for ADUs. The city does not have special ADU-related triggers for stormwater mitigation beyond standard building code drainage requirements that apply to all residential construction. Property owners typically do not need to implement additional stormwater measures solely because they are building an ADU, although standard drainage considerations may apply as part of the general permitting and building process.

San Diego’s ADU plan review process typically takes about 90 to 100 days from submission to permit issuance. This includes an optional pre-plan check of 3 to 5 days, a first review period of up to 60 days, about 30 days for addressing corrections and resubmitting plans, and finally, 15 to 20 days to issue permits once plans are approved. Utilizing pre-approved ADU plans or ensuring initial submissions are thorough and accurate can significantly reduce this timeline.

Yes, ADUs in San Diego can have separate water, gas, and electric meters, but it’s optional. Separate meters are useful if tenants pay their own utilities or for detached units far from the main house. Junior ADUs must share meters with the main home. Installing separate meters involves extra costs, so homeowners should consult local utilities for guidance.

In San Diego, ADU utilities can either be shared or separated with dedicated meters. Shared utilities are more cost-effective and often use sub-meters to track usage. Separate meters—ideal for rentals where tenants pay utilities directly—require coordination with local utility providers and involve higher costs ($3,000–$10,000). Sewer lines are typically shared unless the existing system can’t accommodate extra demand.

No, under California state law (Government Code §65852.2 and §65852.22), HOAs in San Diego cannot prohibit ADUs or JADUs. However, HOAs may enforce reasonable design rules, such as matching the primary home’s style, materials, and colors, and regulating landscaping or setbacks. HOAs cannot impose stricter size limits or additional permit requirements beyond city and state standards.

Yes, an ADU in San Diego can have its own address, especially if detached or with separate utilities, though it’s not mandatory. Attached ADUs typically share the main home’s address but can have a unit number, while JADUs always share the primary address. Homeowners can request a separate address through San Diego’s Development Services Department for mail, utilities, and emergency identification.

No, you cannot build an ADU on an empty lot in San Diego, as an ADU is legally considered an accessory structure that must be built on a lot with an existing or proposed primary residence. If you own a vacant lot, you must first construct a primary home before applying for an ADU permit. However, under Senate Bill 9, certain single-family lots may be eligible for a lot split, allowing a new home on each lot, which could then qualify for an ADU. Additionally, some multifamily-zoned properties may permit ADUs as part of a larger development plan, even without an existing home. While you can submit permits for both a primary residence and an ADU at the same time, the ADU permit will not be approved until the primary dwelling is permitted. Property owners should review zoning regulations or consult the San Diego Development Services Department to determine eligibility for alternative development options.

Yes, San Diego allows multifamily properties to convert existing spaces (garages, basements, storage rooms) into ADUs without numeric limits, provided they meet building codes for safety, ventilation, and energy efficiency. Starting January 2025, up to eight detached ADUs per lot are also permitted under California’s SB1211. Conversions must have separate entrances and comply with fire and safety standards. Replacement parking is generally not required.

Yes, San Diego permits stacking detached ADUs up to 30 feet high, subject to zoning, setbacks, structural, and fire-safety requirements. Stacked ADUs must include reinforced foundations, fire-rated materials (if within five feet of property lines), proper egress, and fire separation. Engineered plans and city approval are required.

Yes, ADUs in San Diego can be attached, sharing at least one wall with the primary residence. They can be conversions of existing spaces, additions, or garage conversions, up to 1,200 sq. ft. Attached ADUs follow the main home’s height and setback rules, require separate entrances, and can share or separate utilities. Additional parking generally isn’t required unless in a Beach Impact Zone. Fire sprinklers are required only if the main house has them.

Yes, two ADUs can be attached to each other in San Diego. This can be done in several ways, such as building two detached ADUs as a single structure, attaching multiple ADUs within multifamily properties, or combining an ADU and a Junior ADU (JADU) attached to the primary residence. Attached ADUs must comply with San Diego’s zoning and building code requirements, including size limitations (up to 1,200 sq. ft.), height restrictions (typically up to 25 feet for attached units), setbacks matching the main home, and fire separation and structural safety standards. Attaching two ADUs offers benefits like more efficient use of space, cost savings through shared utilities and infrastructure, simplified permitting, and improved layouts for multifamily conversions.

No, San Diego does not currently allow building a new ADU with an attached Junior ADU (JADU). As of December 2023, a JADU must be created exclusively from existing space within the primary residence and cannot be constructed as an addition to a new or existing ADU. This change was clarified by San Diego’s Housing Action Package 2.0, eliminating the previous allowance to attach a JADU directly to an ADU. Property owners must ensure that any JADU complies with these updated zoning regulations.

In San Diego, most ADUs do not require additional parking, particularly outside the Coastal Overlay Zone. However, within the Coastal Overlay Zone—specifically the Beach Impact Area—one off-street parking space is required unless the ADU is 500 square feet or smaller, located in a historic district, attached to the main dwelling, in a residential permit parking district, or within one block of a car-share vehicle. Additionally, converting or demolishing a garage or carport for an ADU typically does not require replacement parking, except in some circumstances within the Beach Impact Area. Overall, these rules significantly reduce parking requirements and facilitate ADU development throughout San Diego.

If required, ADU parking in San Diego can be placed in driveways (including tandem spaces), within front, side, or rear yard setbacks if zoning allows, on paved surfaces, or using mechanical lifts. Street parking doesn’t count, and parking can’t encroach on sidewalks, public rights-of-way, or designated open spaces. In Beach Impact Areas, required parking must be provided on-site. Homeowners should verify local zoning rules and HOA restrictions.

ADU permits in San Diego typically cost between $5,000 and $15,000, depending on size, location, and complexity. ADUs up to 750 sq. ft. are exempt from many local impact fees. Additional fees may apply for coastal permits, utility connections, or fire reviews. Costs can be reduced by converting existing spaces, using pre-approved plans, and sharing utilities.

Building an ADU in San Diego typically costs $250–$600 per sq. ft., depending on size, type, and finishes. Smaller and detached units often cost more per sq. ft. due to fixed costs like permits and utility connections. Custom finishes, Coastal Zone regulations, or multi-story structures can push costs over $600 per sq. ft. Cost-saving options include garage conversions, using pre-approved plans, limiting size under 750 sq. ft., and sharing utilities.

Yes, San Diego allows renting ADUs as long-term rentals (minimum 31 days). Short-term rentals under 31 days are prohibited. Owner occupancy isn’t required for ADUs, though it is mandatory for Junior ADUs (JADUs). ADUs must remain part of the primary home’s property title and cannot currently be sold separately. Rent control generally doesn’t apply unless existing stabilization rules cover the property.

No, ADUs in San Diego cannot be used as short-term rentals for stays under 31 days. The city prohibits renting out ADUs through platforms like Airbnb or VRBO to preserve long-term housing availability. San Diego does not issue short-term rental licenses for ADUs, and violations can result in fines or the revocation of rental privileges. To legally rent an ADU, leases must be for a minimum of 31 days. While ADUs cannot be used for short-term stays, homeowners may still rent out rooms in the primary residence as a short-term rental if they obtain the necessary city permits and comply with local regulations.

No, ADUs in San Diego cannot currently be sold separately from the main home; they must remain under the same property title. Although California’s AB 1033 (effective in 2025) allows cities to permit separate ADU sales as condominiums, San Diego hasn’t adopted this policy yet. Currently, ADUs can only be rented as long-term units.

San Diego provides several incentives for ADU construction, including the Housing Commission’s ADU Finance Program offering loans up to $250,000 and technical assistance for eligible low-to-moderate-income homeowners. Previously available CalHFA grants (up to $40,000) for pre-development costs have been fully allocated, but future funding may become available. The city’s ADU Bonus Program allows extra ADUs if some units are designated affordable, with no limit in Transit Priority Areas. Other incentives include utility connection fee waivers and reduced permit fees for affordable ADUs.

San Diego requires ADUs to meet energy efficiency, water conservation, and waste management standards. All ADUs must comply with California Energy Code (Title 24), including insulation, ventilation, and high-efficacy lighting; new detached ADUs require solar panels unless converted from existing space or are JADUs. Water-saving fixtures are mandatory, and drought-resistant landscaping or rainwater systems may be encouraged. Adequate recycling and waste storage are required under the city’s Zero Waste Plan. Sustainable building materials, though not mandatory, are recommended by the city’s Climate Action Plan.

Yes, all ADUs in San Diego must meet California’s Title 24 (Part 6) energy standards, requiring insulation, energy-efficient windows, LED lighting, and proper ventilation. New detached ADUs must have solar panels, though converted spaces (garages, basements) and JADUs are exempt. All new ADUs must be pre-wired for future energy storage and electric appliances (including water heaters, heating, and kitchen appliances), even if gas fixtures are initially used. Compliance is documented through energy forms submitted during permitting.

In San Diego, obtaining an ADU permit typically takes about 3.5 to 4 months, depending on the complexity and completeness of the submitted plans. The city’s standard timeline includes roughly 3 to 5 days for an optional pre-plan check, up to 60 days for the initial plan review, around 30 days for any required revisions, and an additional 15 to 20 days for permit issuance. Using pre-approved plans or submitting thoroughly prepared documents can significantly expedite the permitting process.

Obtaining an ADU permit in San Diego involves several steps: confirming zoning compliance, preparing detailed plans (including structural and site plans, and energy reports), submitting the application digitally to the city’s Development Services Department, and undergoing the city’s review process. The initial plan review typically takes up to 60 days, followed by about 30 days for revisions if needed. After approval, permits are issued within 15 to 20 days, allowing construction to begin. Throughout construction, inspections are conducted, culminating in a final inspection and issuance of a Certificate of Occupancy.