Greater San Diego · San Diego County
Building an ADU in San Diego:
cost, timeline, financing, ROI.
California's deepest published cost data — SnapADU's project-tier pricing makes San Diego the easiest CA city to budget for.
Every dollar figure on this page is sourced — see the references at the bottom. Last verified: May 2026.
01 · Cost
What ADUs cost in San Diego
Total all-in costs for a typical 750 sq ft mid-finish build, by ADU type. San Diego runs $375–$600 per square foot for new detached construction in 2026.
| ADU type | Typical 2026 range |
|---|---|
Detached ADU Mid-finish, 750 sq ft. SnapADU's $465/sq ft anchor aligns with builder competition across the metro. | $300,000–$450,000 |
Attached ADU | $250,000–$375,000 |
Garage conversion | $50,000–$150,000 |
Junior ADU (JADU) | $60,000–$100,000 |
Prefab (installed) | $210,000–$370,000 |
02 · Permits & timeline
How ADU permits work in San Diego
A summary of fees and the approval process. Total all-in permit cost typically runs $6,500–$21,000 (typical ~$8.5K–$12K at 750 sq ft); 60-day statutory ministerial review; 6–8 weeks typical. AB 1332 guarantees a 30-day permit decision on pre-approved plans. For the full San Diego permit guide, see the link at the bottom of this section.
Fee breakdown
- $3,000–$8,000
Building permit + plan check
Plan check is ~65% of the building permit fee.
- $0 under 750 sq ft
Development Impact Fees (DIF)
Waived under SB 13 for ADUs <750 sq ft; $5,000–$15,000 above.
- $2,500–$12,000
Water/sewer capacity
$7,200–$12,000 for new connection; $2,500–$4,000 reusing existing (0.5 EDU reduced rate).
- $5.17/sq ft
School fees
Waived under 500 sq ft.
- ~$1,170 combined
General Plan Maintenance + address assignment
Size limit
1,200 sq ft (detached); attached capped at 50% of primary home (800 sq ft guaranteed minimum statewide); JADU capped at 500 sq ft.
Setbacks
4 ft side/rear for new detached ADUs (state-preempted); 0 ft for conversions of legal existing structures. Height: 16 ft generally, up to 25 ft within 0.5 mi of transit.
Parking
Waived within 0.5 mi of public transit, in historic districts, in permit-parking areas, or for any conversion of an existing structure (state-preempted).
Pre-approved plans
AvailableThe city accepts County of San Diego Standard ADU Plans, Chula Vista Standard Plans, and Encinitas Permit-Ready ADU plans. AB 1332 guarantees a 30-day permit decision on any pre-approved plan submittal.
City program pageAmnesty / legalization
AvailableSDHC ADU Finance Program provides low-income homeowner construction loans + technical assistance. Legalization pathway documented in Information Bulletin 400.
City program pageLooking specifically for San Diego ADU permit fees, the full timeline, or current city requirements?
Full San Diego ADU permit guideWhat's different about San Diego
Local rules that move budgets and timelines
State law preempts most ADU rules — but every city has a few quirks worth knowing before you spend money on design.
- 01
ADU Bonus Program: one bonus market-rate ADU per deed-restricted affordable ADU (15-year affordability term). Unlimited bonus ADUs allowed in Transit Priority Areas — a unique San Diego incentive.
- 02
Coastal Overlay Zone parcels (La Jolla, Pacific Beach, Ocean Beach, Mission Beach) require a Coastal Development Permit on top of the standard ADU permit — material additional time and cost.
- 03
All-electric ADUs qualify for $2,000–$3,000 in Climate Action Plan rebates. June 2025 reforms capped per-lot ADU count and added a Community Enhancement Fee for bonus units.
03 · Financing
How San Diego homeowners pay for an ADU
A typical San Diego build of ~$350K is rarely paid in cash. Five common instruments — pick the one matched to your equity, timeline, and income profile.
HELOC
Best for: Owners with $200K+ equity and a fast timeline.
Variable-rate line of credit secured by your home. Funds available in 2–6 weeks; interest-only payments during draw.
Cash-out refinance
Best for: Long-term owners locking in a lower blended rate.
Refinance your primary mortgage at a higher loan amount and take the difference as cash. Closing costs 2–5% of total loan.
Construction-to-perm
Best for: Owners without sufficient equity for a HELOC.
Single closing covers construction draw + permanent mortgage on completion. Fannie Mae & Freddie Mac now allow projected ADU rental income toward qualification.
RenoFi loan
Best for: Owners short on equity who need to borrow against ADU after-build value.
Underwrites against your home's projected post-renovation value. Typically 30-year fixed, higher rate than HELOC.
CalHFA ADU Grant
Best for: Lower-income California homeowners covering soft costs.
Up to $40,000 forgivable grant for predevelopment (site work, design, permits). Subject to availability and income limits.
Compare full monthly payment math for your scenario:
Run the loan calculator04 · ROI
Does an ADU in San Diego pencil out?
Simple-payback math, anchored to San Diego's May 2026 rental data and a typical mid-finish detached build. This is the dumb-but-honest version — not IRR — so you can sanity-check it on a napkin.
Typical build
$350,000
Monthly rent (1BR)
$2,272
Annual rent
$27,264
Simple payback
13 years
The fuller math
- Cash flow first. A $2,272/mo rent on a $350K build is roughly 7.8% gross yield. Subtract financing cost, vacancy, and operating expenses for the net.
- Property value uplift. A permitted ADU typically adds 20–35% of build cost to appraised home value in the short term — and 80–100% once rental income is documented (FHFA, 2025).
- Why this number is a floor. Simple payback assumes flat rent forever and no appreciation. Real returns include rent escalation, tax benefits, and home value gain — all of which improve the picture.
Rent source: Zillow Rentals + Zumper, May 2026 (studio $1,930/mo median, 1BR $2,272/mo median).
Run the full ROI calculatorFAQ
The questions San Diego ADU homeowners ask first
- How much does it cost to build an ADU in San Diego?
- A mid-finish 750 sq ft detached ADU in San Diego runs $300,000–$450,000, or roughly $375–$600 per square foot. SnapADU's published per-sq-ft anchor of ~$465 reflects mid-market builder competition. Garage conversions land between $50,000 and $150,000.
- What are San Diego ADU permit fees in 2026?
- Total all-in permit fees in San Diego run $6,500–$21,000 depending on size and utility scenario; a typical 750 sq ft detached lands at $8,500–$12,000. Building permit + plan check runs $3,000–$8,000, water/sewer capacity adds $2,500–$12,000, and Development Impact Fees are waived under state law for ADUs below 750 sq ft.
- What is San Diego's ADU Bonus Program?
- San Diego allows one bonus market-rate ADU per deed-restricted affordable ADU (15-year affordability covenant). In Transit Priority Areas, the bonus is unlimited. This is unique to San Diego and meaningfully changes the math for homeowners willing to commit to affordability on one of multiple units.
- Does San Diego accept pre-approved ADU plans?
- Yes — and from three sources: County of San Diego Standard ADU Plans, Chula Vista Standard Plans, and Encinitas Permit-Ready ADU plans. AB 1332 then guarantees a 30-day permit decision on any pre-approved plan submittal. That's roughly half the typical custom-design timeline.
- What rent can a San Diego ADU earn?
- Per Zillow Rentals data from May 2026, San Diego studios rent for a median $1,930/mo and 1-bedrooms for $2,272/mo. Demand is supported by biotech (Torrey Pines), the Navy, UCSD students, and short/mid-term renters in beach-adjacent ZIPs (92107, 92109, 92037).
Compare
How other California cities stack up
We track ADU cost, permits, and rent for these markets too. Click through for a same-shape breakdown.
San Francisco Bay Area
Oakland
Bay Area rents and a free city plan catalog — but Oakland Hills fire-zone parcels carry extra cost.
Greater Los Angeles
Long Beach
The cheapest LA-County coastal labor market with same-day permits on the city's pre-approved plans.
Sacramento Region
Sacramento
The most transparent ADU fee data in California — line-item permits published by the city, total under $6K at 750 sq ft.
Central Valley
Fresno
California's lowest absolute build costs and five free pre-approved plans — but rent yields lag coastal markets.
North Bay
Santa Rosa
North Bay rents on a Sonoma County footprint — strong demand, but WUI fire zones add real construction cost.
San Francisco Bay Area
San Francisco
Highest build costs AND highest rents in California — but lot constraints, DBI delays, and historic review make SF a power-user project.
San Francisco Bay Area
San Jose
The Bay Area's strongest ADU ROI — same-day permits for pre-approved plans, tech rental demand, and Bay Area rents without SF's build-cost premium.
Greater Los Angeles
Pasadena
California's deepest 2025 fee reductions — Pasadena ADUs ≤900 sq ft can save 25–50%+ of city fees with a Housing Agreement.
Greater Los Angeles
Los Angeles
California's largest ADU market: 80+ free pre-approved Standard Plans, the deepest builder bench, and LADBS fees among the lowest of any major CA city.
San Francisco Bay Area
Berkeley
UC Berkeley demand keeps vacancy near zero; an active 2025–2028 amnesty program legalizes pre-2020 unpermitted ADUs without enforcement penalties.
Orange County
Irvine
Highest 1BR rent of any city we cover — but HOA-heavy master-planned communities and Orange County build costs make the math demanding.
Greater Los Angeles
Glendale
Sits between LA and Pasadena geographically; ADUs ≤750 sq ft escape a ~$5K impact fee, but the citywide 1,000 sq ft cap is stricter than state default.
Inland Empire
Riverside
California's strongest ADU payback math — Inland Empire labor runs 30–40% below coastal CA, and rents stay liquid.
Greater Los Angeles
Santa Monica
Premium West LA rents and tight lot supply — but Coastal Zone permitting, seismic retrofits, and pre-1940 housing stock make Santa Monica a power-user project.
Match me with San Diego builders
Calculators get you in the ballpark.
Builders walk your lot.
We'll match you with 2–3 ADU-specialist builders in San Diego, briefed on your project specifics. Most homeowners hear back within 48 hours.