San Jose ADU Cost Guide (2026)
San Jose ADUs cost $220K–$480K all-in in 2026. Neighborhood-by-neighborhood pricing, permit fees, and the financing options most homeowners use.
Last updated: •Reviewed by the aduglossary editorial team
Quick Facts: San Jose ADU Costs
600 sq ft ADU
$220K–$340K
$367–$567/sq ft
800 sq ft ADU
$280K–$420K
1BR standard config
1,200 sq ft ADU
$380K–$480K
2BR+
Permit fees
$12K–$28K
City + school + impact
Permit timeline
5–7 months
Longer than LA
By-right zoning
Yes (up to 1,200 sq ft)
SB 9 stacks
San Jose ADU Cost by Neighborhood
2026 cost-per-square-foot ranges for a typical 600 sq ft new-build ADU, plus the median permit fee and rental demand for each neighborhood.
| Neighborhood | ZIP | $/sq ft (600 sq ft) | Median permit fee | Rental demand |
|---|---|---|---|---|
| Willow Glen | 95125 | $400–$560 | $22K | High |
| Almaden Valley | 95120 | $380–$540 | $20K | High |
| Evergreen | 95135, 95148 | $350–$500 | $18K | Med |
| Alum Rock | 95116, 95127 | $320–$450 | $15K | Med |
| Cambrian | 95124 | $380–$520 | $19K | High |
| Berryessa | 95133 | $340–$480 | $17K | Med |
Permit Fee Breakdown
Typical 2026 fees for a 600–800 sq ft detached ADU. Always verify with City of San Jose Planning, Building & Code Enforcement before submitting.
| Fee | Typical Range |
|---|---|
| Plan check | $2,200–$5,500 |
| Building permit | $2,800–$7,500 |
| School fees | $5.17/sf (varies by district) |
| Impact / capacity fees | $0–$3,500 (waived for ADUs <750sf under SB 13) |
| Total typical range | $6,200–$17,500 |
Climate & Construction Considerations
San Jose has a mild Mediterranean climate — dry summers (80–90°F) and cool, wet winters (50°F average, 14" rain). Seismic Zone D2 means lateral force resistance, holdowns, and shear walls are mandatory; ADUs over 750sf trigger Title 24 energy compliance with cool roofs and high-performance windows. Heat-pump HVAC is now standard under San Jose's Reach Codes. Soil conditions vary — expansive clay near Coyote Creek requires soils reports.
Local Code & Zoning Notes
San Jose's Citywide ADU Ordinance allows up to 1,200sf detached ADUs by-right on most R1/R2 lots. JADUs up to 500sf are permitted inside the primary residence. Setbacks: 4ft side/rear. No owner-occupancy requirement. Pre-approved ADU plans (AB 1332) cut plan check by ~50%. Short-term rental (under 30 days) is prohibited city-wide for ADUs.
San Jose ADU Permits & Timeline
- • Plan check: 5–7 months for full ADU plan check at the City of San Jose Permit Center.
- • Pre-approved plans: San Jose offers a small library of pre-approved ADU plans that cut review to ~3 months.
- • Impact fees: Waived for ADUs under 750 sq ft per California state law (Gov. Code 65852.2).
- • School fees: Apply to ADUs over 500 sq ft — typically $4–$8 per square foot.
- • SB 9 stacking: Allows lot split + ADU + JADU on most single-family lots.
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Frequently Asked Questions
How much does an ADU cost in San Jose in 2026?
$220K–$480K depending on size and neighborhood; the median 600 sq ft build is around $275K all-in including permits.
What's the typical permit fee for a San Jose ADU?
$12K–$28K including plan check, building permit, impact fees, and school fees. Impact fees are waived for ADUs under 750 sq ft under California state law.
How long does it take to permit an ADU in San Jose?
5–7 months for plan check, then 4–6 months to build. Total 10–13 months from contract to certificate of occupancy.
Is an ADU cheaper than buying a starter home in San Jose?
Yes. A 600 sq ft ADU at $275K is roughly 20% of a median San Jose home price, and the rental income typically offsets most of the loan payment.
Can I build two ADUs on one lot in San Jose?
Yes. Under SB 9 and the city's bonus ADU program you can stack a JADU and an ADU, and up to 2 ADUs on larger lots.
What's the best financing option for a San Jose ADU?
HELOC is cheapest if you have equity; construction-perm for homeowners with ~20% equity; renovation loans for tight equity. Use our ADU loan calculator to compare.
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