How Much Does an ADU Permit Cost in San Diego in 2025?

Key Takeaways / TLDR

• Building permits are required for any new ADU build or major renovation in San Diego.
• In 2025, most San Diego ADU permit costs range from about $6,500 to $21,000, depending on size, type, and whether it’s new construction or a conversion.
• Impact fees are fully waived for ADUs under 750 sq ft statewide under SB 13; school fees only apply to units over 500 sq ft (San Diego Unified’s 2025 rate is $5.17/sq ft).
• Water and sewer capacity fees are reduced for ADUs — City fees average ~$1,524 (water) + ~$2,577 (sewer) for about 0.5 EDU, while San Diego County Water Authority meter fees start at $5,859 (<1″).
• New California ADU laws permanently remove owner-occupancy requirements, expand multifamily property ADU rights, and streamline approvals in some coastal zones.
• Bonus ADU Program update: The Affordable ADU Bonus program still allows one unrestricted ADU for each deed-restricted affordable unit (15-year term), but as of 2024–25, the City has introduced caps in certain high-density zones and tightened affordability verification (Pacific Research Institute).

Site conditions like slopes or narrow lots can affect permitting timelines more than base fees alone.

How Much Does an ADU Permit Cost in San Diego?

In 2025, most San Diego ADU building permit fees range from about $6,500 to $21,000, depending on the unit size, type, and project scope. Smaller ADUs (≤750 sq ft) are still exempt from costly development impact fees under SB 13, while school fees only apply to projects over 500 sq ft. Reduced water/sewer connection fees—about $1,524 (water) + $2,577 (sewer) for 0.5 EDU—can help lower total project costs, especially when paired with pre-approved plans that speed up the permit application and Building Plan Review process (City of San Diego). Using the city’s ADU Fee Estimator and proper site preparation strategies can also help avoid additional inspection fees or design revisions, keeping your cash flow steady during construction.

Leverage statewide fee waivers and local incentives to lower your total ADU permit cost while maintaining compliance with building codes.

Why Fees Are Lower Now

Before 2019, ADU projects faced full development impact fees, higher utility connection charges, and longer approval timelines. Since then, California has enacted multiple reforms—most notably SB 13 and AB 68—that capped fees, mandated faster reviews (60 days), and removed certain zoning hurdles. These policy shifts, combined with the City’s pre-approved plan program, have made ADU permitting significantly more affordable and predictable compared to pre-2019.

(Based on 2025 City of San Diego rates; school fees at $5.17/sq ft for >500 sq ft ADUs — San Diego Unified)

City of San Diego ADU Permit Fees (2025)

ADU permit costs in San Diego are made up of multiple line items, not a single flat fee. Rates vary depending on unit size, type (detached, attached, JADU, or conversion), and whether historic review or special inspections apply. Smaller units (≤750 sq ft) still benefit from waived development impact fees under SB 13, and school fees only apply to ADUs over 500 sq ft (San Diego Unified).

JADUs (≤500 sf within the primary home) and garage/basement conversions typically avoid capacity charges, address fees, and school fees, making them significantly cheaper to permit.

TABLE: City of San Diego Permit Fees (2025)

This information was pulled from the Fee Schedule for Construction Permits-Structures from the City of San Diego.

Often-missed City fees

Homeowners often budget for plan check and inspections—but miss the small City add-ons that show up at submittal, issuance, or during inspections. The table below flags these line items and their timing (e.g., General Plan, mapping, lead hazard, state valuation fees, addressing, stormwater) so you can plan cash flow and avoid last-minute surprises. Use it as a quick checklist at each stage of permitting.

TABLE: Often-missed City of San Diego Fees & When Paid (2025)

Understanding ADU Fees Waived with SB 13 & Other 2023–2025 Laws

From 2020 through 2025, California has passed a series of laws that lower building permit fees, remove outdated zoning requirements, and streamline the permit application process for Accessory Dwelling Units (ADUs). These measures can save San Diego homeowners thousands in project costs, from development taxes to reduced Water/Sewer Connection Fees, while cutting months off Building Plan Review and Residential Site Plan Review timelines. Knowing how each law works is key to accurate cost estimation and avoiding unnecessary application fees.

• SB 13 (2020–ongoing) – Waives development impact fees, including Traffic Impact Fees and park fees, for ADUs under 750 sq ft. Junior ADUs (JADUs) inside the main home are also exempt from school fees and utility connection fees, helping reduce overall project value costs. (Senate Housing Committee)
• AB 976 (2024) – Permanently removes owner-occupancy requirements, giving property owners—including those with garage conversions or detached garages—more flexibility in renting their units. (California ADU Experts)
• AB 1033 (2023) – Allows cities to opt in to rules permitting ADUs to be sold separately as condos, potentially increasing home equity and resale options. (Builders Now)
• SB 1211 (2024) – Expands allowable ADUs on multifamily lots to eight detached units, with fewer parking mandates, creating more housing opportunities without heavy fire impact fees.
• AB 2533 (2024) – Creates a statewide amnesty for legalizing unpermitted ADUs and JADUs built before 2020, even if they don’t meet current building codes or land use plan review requirements. (City of Gardena)
• AB 3057 (2024) – Extends CEQA exemptions to JADUs, speeding up Fire – Plan Review and reducing environmental review delays. (California YIMBY)
• SB 1077 / SB 1092 (2024) – Reduces coastal development permit delays for ADUs in San Diego’s historic districts and other coastal zones by streamlining Department of Building and Safety approvals. (Ohana Dwellings)

Laws like SB 13 and AB 976 continue to expand cost-saving and flexibility options for ADU projects.

Is There an ADU Permit Fee Waiver in San Diego?

The City of San Diego no longer provides a blanket plan-check fee waiver for Standard ADUs or Manufactured ADUs, but impact fees remain waived for units under 750 sq ft under statewide law SB 13. While the earlier trial permit waivers—such as Parks Mitigation Fees or certain City of San Diego fee schedule reductions—ended in 2024, targeted programs still exist for qualifying projects. Understanding these policies can help with accurate cost breakdown and use of the Building Permit Fee Estimate Worksheet during the application process.

State law still waives impact fees for ADUs under 750 sq ft, even if local plan-check fee waivers have ended.

Current Fee Waiver & Incentives

• Impact Fees Waived for Small ADUs – Units under 750 sq ft continue to avoid development impact fees, including Traffic Impact Fees and other local assessments, throughout California and in San Diego’s historic districts.
• No Citywide Plan-Check Waiver – San Diego no longer offers a blanket plan-check fee waiver, unlike the short-lived County of San Diego pilot, which also reduced certain Water System capacity fees and ended in 2024.
• Green or Affordable ADU Incentives – Expedited Fire – Plan Review and Residential Site Plan Review are available for qualifying green or income-restricted ADUs, particularly under the Affordable ADU Bonus Program and local housing finance initiatives (Fortune ADU).
• Bonus ADU Program Updates & Limits – As of mid-2025, the City Council has capped the number of bonus ADUs (4 on small lots, up to 6 on larger ones), introduced off-street parking mandates outside Transit Priority Areas, and restricted new builds in wildfire zones and certain cul-de-sacs (Wesley Tyler Real Estate Group).

These updates mean that while you can still estimate ADU fees and costs using the City’s online calculator, you’ll want to factor in new zoning laws, potential Photovoltaic System Fees, and other site-specific charges before finalizing architectural plans.

Quick Overview Table

San Diego ADU Incentives & Financing Programs (2025)

Notes & Context

• Affordable ADU Bonus Program: Revised in mid-2025, San Diego City Council capped bonus ADUs by lot size (4–6 units) in response to local feedback and prohousing goals (Axios).
• CalHFA ADU Grant: Administered by the California Housing Finance Agency, offering up to $40,000 for pre-construction costs; income qualifications and funding availability vary (CalHFA).
• SDHC Program: The San Diego Housing Commission provides loans plus technical help; completion requires affordable rent restrictions and owner-occupancy (SDHC).
• County Green Incentive: Unincorporated areas offer a flat 7.5% discount on permit-related fees for green-design projects (County of San Diego).
• Expedited Review: The City’s Permit Now and Sustainable Buildings Expedite programs fast-track qualifying ADUs and can save time and reduce costs (City of San Diego).

Water & Sewer Capacity Fees

San Diego calculates water and sewer charges based on Equivalent Dwelling Units (EDUs)—each roughly equivalent to a standard single-family home. The number of EDUs for an ADU depends on its fixture count (20 fixture units ≈ 1 EDU) and whether it’s on a separate meter.

How Capacity Fees Work (EDU-Based)

EDU Metric: One typical single-family residence counts as 1 EDU. A partial-unit ADU with around 20 fixture units may equal 0.5 EDU.
(City of San Diego)

City of San Diego Capacity Fees (per EDU):

• Water capacity: historical base of $3,047
• Sewer capacity: historical base of $4,124

Actual 2025 fees may be higher or indexed for inflation.
(City of San Diego)

County Water Authority Meter-Size Charges:

• <1″ meter: ~$5,859 ($5,700 + $159)
• 1″ meter: ~$9,374 ($9,120 + $254)

These are one-time capacity charges linked to meter size.
(San Diego County Water Authority)

Fixture counts directly impact water and sewer capacity fees, so plan your ADU plumbing strategically.

When Fees Are Waived, Reduced, or Costly

• $0 Fees: If an ADU uses the primary dwelling’s existing fixtures and meter, it may not trigger additional capacity charges—especially for JADUs or small, internal units.
• Reduced Fees (~0.5 EDU): A modest standalone ADU may incur roughly half of the full EDU charges—significantly lowering costs.
• Full EDU Fees (~$8,000–$10,000+): Larger ADUs with separate in‑house meters and full fixture setups may trigger full-meter fees from both the City and County.

Smart Strategies to Avoid Higher Fees

• Design for shared connections: Use water fixtures already connected to the main dwelling where possible.
• Fixture optimization: Keep fixture units—sinks, showers, toilets—to a minimum (around 20 units), capping near 0.5 EDU.
• Avoid upsizing meters: Don’t install a new separate meter unless necessary—especially to evade steep County capacity charges.
• Defer capacity fees: For certain qualifying projects, San Diego may allow capacity fee deferrals. Ask the Public Utilities or Development Services departments whether this applies.
  (County of San Diego, SnapADU, SnapADU, City of San Diego)

Example Fee Scenarios

• County meter charges apply only if a new, separate meter is installed.

Development Impact & School Fees

What You Need to Know

• Development impact fees (e.g., parks, libraries, transportation) are fully waived for all ADUs statewide—thanks to SB 13—even those over 750 sq ft, provided fee assessments are proportionate to the primary dwelling or allowed through local waivers (e.g., up to 1,200 sq ft in single-family zones in San Diego) (How To ADU ™).
• School impact fees under San Diego Unified apply only to ADUs larger than 500 sq ft, at a current rate of $5.17 per square foot.

Note on Other School Districts

San Diego Unified is just one district; rates and rules vary elsewhere. For example, some districts set different thresholds or higher per‑sq‑ft fees for new construction. Always check with your local school district for the most accurate information (San Diego Unified School District).

Example Fee Calculations

How Long Does It Take to Get an ADU Permit in San Diego?

In 2025, San Diego homeowners typically receive ADU permit approval in 2–4 months for straightforward projects using pre-approved plans. Custom designs or complex site conditions can stretch the timeline to up to 6 months. City programs like Express Plan Check (40–50% faster reviews) and Rapid Review for eligible projects further accelerate approvals. Fast-track routes—with pre-approved or standard designs—can see permits issued in as little as 2 weeks under Priority or Express programs.

Notably, pre-approved plans now enjoy a 30-day first-round review minimum, and Express Plan Check offers accelerated turnaround on eligible permits (City Express Plan Check) (Rapid Review).

Typical Permit Timeline

Common Permit Delays & How to Avoid Them

Permit approval delays for ADUs in San Diego often stem from documentation errors and zoning conflicts. Recent improvements—such as pre-approved plans, upgraded online permitting systems, and updated coastal development laws—are helping homeowners move through the building process faster while avoiding costly setbacks.

Documentation Errors

Missing or incomplete paperwork—like California Energy Code compliance forms, property surveys, or required permits—can stall your application. Using pre-approved plans ensures alignment with City of San Diego fee schedules, zoning requirements, and Fire – Plan Review standards from the start, reducing discrepancies. These vetted plans also help avoid unnecessary costs tied to Electrical Permit State Surcharge, Plumbing Permit State Surcharge, or other supplemental fees. (GatherADU)

Zoning and Code Issues

Setback violations, height restrictions, and lot coverage overages are common triggers for review delays. Garage Conversion Permits and coastal properties historically faced lengthy Coastal Development Permit (CDP) processes, but as of 2025, SB 1077 exempts many ADUs in non-sensitive coastal zones from CDP requirements. This means faster approvals, especially in areas outside San Diego’s historic districts. (AduAbl, ohanadwellings.com)

City’s Online Portal

San Diego’s updated permit portal now allows digital submissions, integrated Water and Sewer Fee Calculation tools, and real-time tracking, making it easier to correct errors quickly and maintain project momentum.

Use of Pre-Approved Plans

Pre-approved designs, offered by cities like San Diego, Encinitas, and Chula Vista, help cut review cycles and keep project costs predictable. These plans already meet zoning laws and architectural plan standards, reducing back-and-forth with plan reviewers and minimizing the risk of added fees like Water Treatment Capacity fees or CWA Water System capacity fees. (onestopadu.com, Fortune ADU)

Submitting complete, code-compliant plans—especially pre-approved designs—minimizes costly resubmissions and keeps your ADU permit on track.

Get Started With Your ADU Permit

Ready to turn your ADU plans into reality? At Better Place Design & Build, our team guides San Diego homeowners through the entire permitting process — from initial site evaluation to securing final approval. With 2025’s updated laws, waived impact fees, and streamlined approvals, now is one of the best times to start.

Before you begin, we recommend:

• Using the City of San Diego’s updated fee calculators (Development Services Fee Calculator) to estimate your costs accurately.
• Considering pre-approved ADU plans (City’s Pre-Approved Plan Set Program) to save both time and money.
• Scheduling a free consultation with our ADU specialists to review your property, design options, and the most cost-effective approach for your build.

Get started today → Book your ADU consultation.

Use the City’s updated fee calculators and pre-approved plans to streamline applications, reduce costs, and shorten approval timelines.