San Diego ADU Builders

Under San Diego’s 2025 rules, single-family lots can have 1 JADU plus 2 ADUs (1 converted, 1 detached) (Inside San Diego). The ADU Bonus Program allows more if one is affordable, but mid-2025 reforms restrict it in low-density zones and cap totals (e.g., max 4 on <8,000 sq. ft. lots) (SDHC). At minimum, 1 ADU + 1 JADU are always allowed. This also applies for granny flats, guest houses, and in-law suites.

San Diego has no minimum lot size for ADUs; state law prohibits it CA HCD). The smallest ADU allowed is 150 sq. ft., while the city caps most at 1,200 sq. ft. depending on zoning and lot coverage (City of San Diego). Even small lots can add an ADU if setbacks and safety codes are met.

Yes. In San Diego’s Coastal Overlay Zone, many ADUs require a Coastal Development Permit (CDP), especially detached units or additions (City of San Diego). Conversions or JADUs may be exempt. Since Sept. 7, 2022, the City can issue ministerial CDPs in non-appealable areas, but appealable zones near the shoreline still need fuller review and Coastal Commission oversight. State ADU law applies, but expect extra time if a CDP is required.

In 2025, most San Diego ADUs take 10–16 months total, with 6–12 months for construction after permits (San Diego Housing Commission). Expect 4–8 weeks for feasibility, 2–4 months for permitting (state mandates 60 days), and longer if utilities or coastal permits add complexity. Using pre-approved standard plans can cut review to 30 days. Detached units average ~12 months; garage conversions and interior ADUs often finish faster.

In 2025, most San Diego ADUs take about 10–16 months from first consultation to move-in, with construction itself averaging 6–12 months once permits are issued. The timeline typically includes 4–8 weeks for pre-design and feasibility, 2–4 months for permitting under California’s 60-day review mandate, and 6–12 months of on-site build depending on site conditions, utilities, and scope. San Diego also offers a 30-day expedited review for projects using pre-approved standard plans, which can shorten the overall schedule. Detached backyard cottages usually run closer to 12 months door-to-door, while garage conversions and interior ADUs may finish faster. Complex sites, service upgrades, or coastal permits can extend the process, so planning with complete intake documents and early utility coordination is key (San Diego Housing Commission).

In San Diego, ADUs generally require no parking (City of San Diego). Outside the Coastal Overlay Zone, zero spaces are needed. In the coastal zone, parking applies only in the Beach Impact Area outside Transit Priority Areas—one space per ADU—though exemptions cover units <500 sq. ft., sites near car-share, or garage conversions. Bottom line: most ADUs have no parking requirement. However, a detailed Feasibility Study will help you understand whether this is needed for your property.

When building an ADU in San Diego, expect to pay standard permit and school fees, but there are key exemptions that save costs. Development impact fees are waived for ADUs under 750 sq. ft., and larger ADUs only pay fees proportional to their size (City of San Diego). Utility connection fees apply if a new water or sewer connection is required, but San Diego offers a 50% reduction on capacity charges for ADUs, and conversions that don’t need new connections avoid these fees entirely . School fees are exempt for units under 500 sq. ft., but apply to larger ADUs (e.g., ~$4.80 per sq. ft. in San Diego Unified as of 2024). Permit fee waivers that once existed have expired, though the 2025 ADU Bonus Program now imposes a small “community enhancement” fee for affordable or bonus ADUs under 750 sq. ft. Bottom line: small and conversion ADUs enjoy major fee savings, making them one of the most cost-effective ways to add housing in San Diego.

Yes. San Diego accepts pre-approved ADU plans from the County, Chula Vista, and Encinitas, allowing a 30-day streamlined review instead of 2–3 months (California AB 1332). Plans must fit your site and be licensed, but they cut permitting time and reduce uncertainty.

When building an Accessory Dwelling Unit in San Diego, permits typically take 2–3 months, as California law requires cities to decide within 60 days of a complete application (CA HCD). More complex sites (coastal or hillside) may take 3–4 months. Submitting complete building plans and documents up front speeds the process, while using pre-approved plans can reduce review to just 30 days. A building permit is always required before construction begins.