San Diego · Cost guide

How much does an ADU cost in San Diego? (2026)

Detached, garage conversion, attached, and JADU — what each build type actually costs in San Diego, what the PRADU program saves you, and what to expect for ROI.

Last reviewed: 2026-06-14

Quick answer

In 2026, building a detached ADU in San Diego typically costs $300,000–$450,000 all-in, while a garage conversion runs $80,000–$200,000. Per-square-foot costs range from about $200 (basic garage conversion) to $600 (premium detached). Soft costs — design, plan check, building permit, school fees, and utility hookups — typically add $15,000–$35,000 on top of hard construction.

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Cost breakdown by build type

Total project costs in 2026 San Diego — hard construction plus typical soft costs — for a mid-finish build. Coastal neighborhoods (La Jolla, Del Mar, Pacific Beach) push to the top of each range due to premium labor and stricter design review.

Build type	Typical size	Total cost	Per sqft
Detached ADU	600–1,200 sqft	$300K–$450K+	$375–$600
Garage conversion	350–500 sqft	$80K–$200K	$200–$400
Attached ADU	500–1,000 sqft	$275K–$400K	$275–$400
Junior ADU (JADU)	≤500 sqft	$110K–$185K	$220–$370
Prefab / modular	400–1,000 sqft	$170K–$325K	$260–$370

The PRADU program — how it changes the math

The biggest single cost lever in San Diego is the Pre-Approved ADU (PRADU) Programrun by the city's Development Services Department. The program offers a catalog of architectural plans that have already passed full plan check. Picking one collapses your permitting from months to weeks — DSD only reviews site-specific factors (zoning, foundation, utility connections) rather than re-auditing the architecture.

Stacked with the 2026 HCD impact-fee waiver for ADUs under 750 sqft — no local impact fees, no school facility fees under 500 sqft — typical PRADU homeowners save $8,000–$15,000 on design + plan-check and another $5,000–$15,000 on fees. Total potential savings: $13K–$30K + 2–3 months off your timeline.

The trade-off: PRADU plans are pre-approved as designed and can't be modified. If your lot has unusual slope, alley-only access, or your needs require a layout the catalog doesn't cover, custom is the only path.

Hard costs vs. soft costs

On a typical San Diego ADU project, soft costs are $15,000–$35,000on top of construction. Knowing them upfront is the difference between “on budget” and “short $20K at framing.”

Hard costs

· Site prep, excavation, foundation
· Framing, roof, exterior
· Plumbing, electrical, HVAC
· Insulation, drywall, paint
· Cabinets, counters, appliances
· Flooring, fixtures, finishes

Soft costs (SD)

· Design / architectural plans: $8K–$20K
· Structural & energy engineering: $1.5K–$4K
· DSD plan check: $2K–$5K
· Building permit: $3K–$7K
· School fees (≥500 sqft): $2K–$5K
· Utility hookups (SDG&E / water / sewer): $0–$12K
· Survey, soils, contingency: $2K–$5K

ADUs under 750 sqftskip most impact and utility connection fees under 2026 California rules. Under 500 sqft, school fees go away too. This is why “build smaller” is so often the math-optimal call.

ROI — what an SD ADU actually returns

Standalone backyard ADU 1-bedrooms in San Diego typically rent for $2,400–$3,400/month in 2026, depending on neighborhood and finish. Coastal proximity is the biggest variable — La Jolla / Pacific Beach / Encinitas at the top, inland neighborhoods lower.

Sample ROI — $325K detached 800 sqft ADU

· Construction cost: $325,000
· Gross rent (1BR @ $2,900/mo): $34,800/yr
· Net rental income after expenses: ~$28,000/yr
· Cash-on-cash return: ~8.6%
· Property value lift: $150K–$225K
· Approx. rental payback: 10–13 years

How to lower the cost

1. Use a PRADU plan ($8K–$15K + 2–3 months saved)
Skip custom architecture, skip full plan check. The single highest-leverage move available.
2. Stay under 750 sqft ($5K–$15K in fees saved)
2026 California rules waive impact fees and most utility connections under 750 sqft; school fees go away under 500.
3. Get 3+ written bids
Bids for identical scopes routinely vary 20–40% between SD builders.
4. Consider a garage conversion
$80K–$200K vs $300K+ for new detached. Caveat: older SD garages often need structural reinforcement ($10K–$25K).

When SD ADU costs go up unexpectedly

Coastal Overlay Zone. Properties west of I-5 face additional design review and permit timelines. Add 2–4 months and $5K–$10K in design + review.
Hillside / canyon lots. Retaining walls and deep foundations add $15K–$50K. La Jolla, Mt. Soledad, and many inland canyon lots qualify.
Brush / fire-hazard zones. Many SD County hillside neighborhoods (Scripps Ranch, Rancho Bernardo) require sprinklers + ignition-resistant materials. Add $8K–$20K.
Old main panel. Pre-1990 electrical panels often need upgrade for ADU service. Add $3K–$10K.
Change orders mid-build. Mid-project changes are typically billed at 15–25% above original line item. Lock the spec first.

Sources

City of San Diego — Pre-Approved ADU (PRADU) Program ↗Official PRADU plan catalog and process.
California HCD — 2026 ADU Handbook ↗Statewide fee-waiver rules (under 750 sqft) effective 2026.
Apartment List — San Diego Rent Report ↗Current 1-bedroom rent data for ROI estimates.
Contractors State License Board (CSLB) ↗License verification for any San Diego ADU builder.

Last reviewed: 2026-06-14. Cost ranges are 2026 estimates and shift with materials prices, labor markets, and lot conditions. Always verify with the official source and get written bids before making decisions.

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See also our free ADU cost calculator, the LA ADU cost guide, or the California ADU guide.

Frequently asked

San Diego ADU cost — common questions

How much does it cost to build an ADU in San Diego in 2026?

In 2026, a detached ADU in San Diego typically costs $300,000–$450,000 all-in (about $375–$600 per square foot for turnkey construction). Garage conversions run $80,000–$200,000. San Diego construction labor is slightly cheaper than LA but more expensive than Sacramento or Phoenix.

What's the PRADU program?

San Diego's Pre-Approved ADU (PRADU) program offers pre-reviewed plans through the Development Services Department. Picking a PRADU plan skips most of the architectural plan check — only site-specific factors get reviewed. Typical savings: $8,000–$15,000 in design + plan check costs and 2–3 months off the permitting timeline.

Are ADU fees waived for smaller units in San Diego?

Yes — under California's 2026 HCD rules, ADUs under 750 square feet are exempt from local impact fees and most utility connection charges throughout San Diego. ADUs under 500 square feet skip school fees too. Combined, these waivers save $5,000–$15,000 versus building over 750 sqft.

How much rent can a 1-bedroom ADU in San Diego get?

1-bedroom ADUs in San Diego typically rent for $2,400–$3,400/month in 2026 depending on neighborhood — coastal areas (La Jolla, Pacific Beach, Encinitas) command the top of the range, while inland neighborhoods like El Cajon and Chula Vista run lower. ADUs generally rent at a premium over apartments due to privacy and standalone unit appeal.

What's the ROI on a detached ADU in San Diego?

On a $325,000 detached ADU renting at $2,800/month, annual net rental income runs roughly $27,000–$30,000 after expenses — a cash-on-cash return of 8–10%. Property value typically lifts by $150,000–$225,000 since San Diego homes with permitted ADUs sell at a premium in this tight market.

How long does ADU construction take in San Diego?

Plan on 12–18 months for a detached ADU: 2–4 months for design, 3–5 months for permitting (faster with PRADU), and 6–9 months for construction. Garage conversions run 8–12 months total. Coastal lots and historic neighborhoods add time due to additional review.

Can I get a loan to build an ADU in San Diego?

Yes — HELOC, cash-out refinance, ADU-specific loans from lenders like RenoFi, or California's CalHFA ADU Grant Program (up to $40,000 for low- and moderate-income homeowners) all work. Specialty design-build firms like Snap ADU and Better Place Design also offer in-house financing or builder-financed options.

Do I need a contractor licensed in San Diego specifically?

No — California has a single statewide contractor license (CSLB). You need a CSLB-licensed General Building Contractor (Class B) for any ADU project over $500. Verify the license is active and complaint-free at cslb.ca.gov before signing.