What happens if you skip the permit (and you needed one)
- Stop-work orders cost $500–$1,500 in fines, plus the city can place a lien on your property and require removal or unpermitted-unit disclosure that kills a future sale for years.
- Insurance denial: homeowner policies explicitly exclude unpermitted structures; a fire or injury claim on an unpermitted ADU will be flatly denied, leaving you liable for six-figure losses.
- Title/sale blocker: California Real Estate Disclosure law requires disclosure of unpermitted work; buyers' lenders will refuse to fund, and title companies won't insure — your property becomes nearly unsaleable without costly remediation.
- Refinance/equity lock: if you try to tap home equity or refinance, the lender will order a title search that flags the unpermitted unit and freeze the loan until you obtain a retroactive permit (often impossible) or remove the unit.
San Jose ADU permits — the key details
San Jose has adopted California Government Code 65852.2 (Accessory Dwelling Units) and AB 681 (Junior ADUs) as local law. That means the city cannot require owner-occupancy for detached ADUs under 800 sq ft, cannot impose parking if you're within a half-mile of transit, cannot restrict rent, and cannot impose design review that varies materially from the primary residence. However, the city still requires full building permits and plan review for electrical, plumbing, mechanical, and structural compliance — there is no exemption. All ADUs (detached, garage conversion, junior ADU, above-garage) go through the Building Department's 'ADU Streamline' track, which has a mandatory 60-day review window (AB 671). If the city doesn't approve or deny within 60 days, your application is deemed approved — but in practice, San Jose hits the deadline because the ADU Streamline process is well-staffed and pre-screened applications are routed directly to a single reviewer. The city's online portal (permit.sanjoseca.gov) is the only filing method; there is no walk-in permit desk for ADUs. You must upload complete sets: site plan, floor plans (scaled), electrical one-line, plumbing schematic, foundation/structural detail (if detached), and proof of utility capacity from PG&E or SJWATER. No preliminary or sketch reviews are offered.
Setback and lot-size rules are where detached ADUs most often get rejected in San Jose. State law (65852.2(e)) requires a minimum setback of five feet from the rear and side property lines for detached ADUs. San Jose's code adds that the ADU must not exceed 55% of the lot area on single-family lots and must not reduce the usable open space of the primary residence below 350 square feet per California Title 24. In practice, this kills many proposed detached ADUs on lots under 3,500 square feet in dense neighborhoods like Japantown or the Sycamore corridor. Lot surveys are mandatory if your property record doesn't clearly show setbacks (most don't). A full boundary survey costs $800–$2,000 and adds 2–3 weeks to your timeline. Garage conversions and junior ADUs (750 sq ft maximum, interior remodel only) face much looser setback rules because they don't add to the footprint. If your lot is under 2,500 square feet, a detached ADU is almost certainly out; a garage conversion or junior ADU is your only path.
Utilities and infrastructure are the second-biggest chokepoint. San Jose requires a separate electrical meter (not a sub-meter) for each ADU; the city will not permit an ADU on the same meter as the primary house. You must obtain a 'will-serve' letter from PG&E confirming the service upgrade can be done and roughly what it will cost ($3,000–$8,000 depending on distance from the main panel). Water and sewer are less problematic — you can use a separate meter or a sub-meter — but you must show that your lot's sewer connection has sufficient capacity. If your house was built before 1970, the city often requires a sewer-scope video inspection ($400–$600) to confirm no root intrusion or pitch failure before the ADU is approved. Stormwater is rarely a standalone issue in San Jose unless you're in a mapped flood zone or your lot drains toward a neighbor's foundation; if so, you may need to add a French drain or dry well ($2,000–$5,000). These utility letters must be obtained before you file and uploaded with your permit application. Many applicants skip this step, get dinged by the plan reviewer, and lose 2–4 weeks resubmitting.
Parking is largely waived in San Jose due to AB 680 (passed 2021) and the city's December 2022 ADU ordinance update. If your property is within a half-mile of a transit stop (BART, VTA light rail, or rapid bus) or in a transit village, no parking is required at all. For properties outside the half-mile radius, the city requires one parking space if the ADU is one bedroom or fewer; two if two bedrooms or more. A 'parking space' can be uncovered, tandem, or shared driveway space — it does not need to be a dedicated garage or carport, which saves money and lot space. San Jose's GIS parcel map and transit tool (online) will tell you instantly if you qualify for the waiver. If you don't and need to provide parking, show it on your site plan with dimensions (9 ft wide, 18 ft deep minimum). This is almost never a deal-breaker, but it does consume lot space and can force you to choose a smaller ADU or a junior ADU instead of a detached unit.
Plan review and inspection timelines are predictable because San Jose has streamlined the ADU track. Once you file a complete application (no incomplete submissions are accepted — the system will auto-reject), the city assigns a single building official to your case within 3 business days. First response (approval with conditions, or detailed rejection) typically arrives within 2–3 weeks. If there are minor comments (e.g., 'clarify the electrical panel schedule'), resubmission takes 1 week and re-review is 1 week. If there are major rejections (e.g., 'setback violation, redesign required'), you lose 4–8 weeks redesigning with an architect. Once approved, you can obtain your permit and begin construction. Inspections happen in sequence: foundation (if detached), framing, rough electrical/plumbing, insulation, drywall, mechanical, final building + electrical + plumbing + planning sign-off. Each inspection must be scheduled online and passed within 5 business days or you lose your slot and reschedule (adds 1 week). Total construction inspection period is typically 6–10 weeks. From permit issuance to final occupancy, expect 12–20 weeks for a garage conversion or junior ADU; 16–28 weeks for a detached unit (due to foundation and longer framing).
Three San Jose accessory dwelling unit (adu) scenarios
San Jose's ADU Streamline Process and the 60-Day Review Shot Clock
California AB 671 (2021) mandates that local agencies process ADU permit applications within 60 days of submission. San Jose implemented this via its ADU Streamline process, and the city publishes a dedicated tracker on its permit portal (permit.sanjoseca.gov). If you submit a complete application on a Monday, the city has 60 calendar days to issue or deny — no extensions unless you voluntarily request changes or the city identifies a code inconsistency that requires a local hearing. In practice, San Jose's ADU Streamline desk hits the deadline in over 95% of cases because the city has staffed the unit and built a pre-screening filter: applications are automatically routed to a single assigned building official on day 3, and incomplete submissions are bounced back immediately with a detailed checklist of missing items. The applicant then has 15 days to resubmit; the 60-day clock pauses during the resubmission. This is faster than San Jose's standard building permit track (which runs 90–120 days for a single-family home). However, the 60-day window applies only to the initial approval/denial decision — it does not include the time to obtain a final Certificate of Occupancy. Once permitted, construction inspection timelines are separate and typically add 12–20 weeks depending on the ADU type.
The streamline process favors complete, pre-reviewed applications. San Jose's plan reviewer (assigned by day 3) will issue a single 'Request for Information' (RFI) list within 15–20 days. If you submit a well-prepared package upfront (site plan from a surveyor, architectural drawings, utility letters, structural calculations if needed, geotechnical report if required), the RFI list is usually short: clarify the electrical panel schedule, confirm PG&E service, add a detail for egress window height, etc. Resubmitting these fixes takes 3–5 days, and the second review cycle completes within 10 days. Most junior ADUs and garage conversions clear in two review cycles (28–35 days total). Detached ADUs and above-garage units with structural or geotechnical flags typically require two RFI cycles and clear by day 50–55. The key is hiring a permit expediter or architect upfront to prepare a submittal that anticipates the city's questions. Many homeowners try to submit rough sketches and utility estimates, get a 10-item RFI, panic, and lose weeks redesigning with an architect. Spend $2,000–$3,500 on a permit consultant upfront to prepare the application; you'll save $5,000–$10,000 in time and rework.
San Jose's online-only filing system means no walk-in permit desk, no verbal pre-approvals, and no sketching with a reviewer. You must upload all plans, letters, and calculations as PDFs into the permit portal. If you forget a utility letter or don't scale your floor plan, the system auto-rejects before a human eyes it. This is frustrating but fair — it forces rigorous preparation and eliminates the 'submit anything and see what sticks' mentality that bogged down traditional permitting. The portal also publishes live timelines: you can see your assigned reviewer's name, the current RFI issued date, and the 60-day deadline clearly printed. If you're on day 40 and still in RFI, you know you're cutting it close. Most applicants find the transparency helpful, even if the lack of a verbal pre-screening feels cold at first.
Utility Metering, Separate Connections, and San Jose's Infrastructure Rules
San Jose requires a separate electrical meter for every ADU — not a sub-meter, not a dedicated breaker on the main panel, but a full new service with its own PG&E meter. This is driven by California Title 24 (Building Energy Efficiency Standards), which mandates that each dwelling unit have independent utility metering to track energy use and support demand-side management. In practice, this means the electrical contractor must run a new service line from the street pedestal to a new 100–200 amp meter at the ADU, with a disconnect and main breaker independent of the primary residence's service. The cost varies wildly: if the new meter is 50 feet from the existing service line, the cost is $2,000–$3,500 (labor + materials + PG&E interconnection fee). If the pedestal is 200+ feet away (common on large rear lots), or if a power pole must be relocated, the cost rises to $5,000–$8,000. You must obtain a 'will-serve' letter from PG&E before filing the permit; the letter specifies the location of the new meter and the estimated cost. PG&E typically takes 2–3 weeks to issue a will-serve letter. Delays here are common and directly extend your permit application timeline.
Water metering in San Jose is more flexible. You can use a separate water meter (SJWATER charges a one-time meter installation fee, ~$400–$600, plus connection), or you can use a sub-meter that measures the ADU's consumption but remains on the property owner's main account. A sub-meter is cheaper ($150–$300) and is acceptable to the city, but many lenders and tenancy laws favor separate accounts for lease clarity. Sewer drains through a single connection; you cannot run a separate sewer line unless the ADU is detached and 50+ feet from the primary house (rare in San Jose's dense neighborhoods). Stormwater is site-dependent: if your lot has good drainage and no wetlands or flood zone designation, you may only need grading/swale; if you're near a creek or in a mapped flood zone, you'll need engineered drainage (French drain, rain garden, permeable paving) that can cost $2,000–$4,000. Gas (heat, cooking) can be either separate (new meter from PG&E) or a sub-meter on the main line; the city accepts both.
The biggest pitfall is failing to obtain utility letters before filing. Many applicants assume 'the contractor will figure it out' and submit permit applications with placeholder language like 'new electric service TBD.' The building official will issue an RFI: 'Provide PG&E will-serve letter confirming service availability and estimated cost.' You then have to contact PG&E (takes 2–3 weeks), obtain the letter, upload it, and resubmit — you just burned 2–4 weeks of your 60-day window. Pro move: call PG&E and SJWATER immediately after you've decided on the ADU location and unit size. Ask for a will-serve letter and a water/sewer capacity letter. These usually arrive in 2–3 weeks and cost nothing. Upload them with your permit application on day 1. The plan reviewer will not have to ask, and your timeline stays on track.
200 East Santa Clara Street, San Jose, CA 95113 (City Hall). Permits desk is on the 3rd floor. No walk-in ADU services; online filing only.
Phone: (408) 535-3500 (general) or (408) 535-8000 (permits desk — ask for ADU Streamline) | https://permit.sanjoseca.gov/ (San Jose Permit Portal — create account, select ADU from project type dropdown)
Monday–Friday 8:00 AM–4:00 PM, closed City holidays. Phone: M–F 8 AM–5 PM. Online portal open 24/7.
Common questions
Do I have to own and live in the primary residence to build an ADU in San Jose?
No, not anymore. California Government Code 65852.2 eliminated owner-occupancy requirements for detached ADUs under 800 square feet. San Jose adopted this, so you can own a primary residence via a trust, investment company, or corporate entity and still build an ADU. However, if you build an above-garage or interior junior ADU (footprint expansion or interior remodel over 800 sq ft), state law allows the city to require owner-occupancy for the first five years in some cases — check with the San Jose Building Department in writing before filing. Most junior ADUs (750 sq ft, interior only) are exempt from owner-occupancy, but above-garage additions (over 750 sq ft) may trigger a five-year primary-residence requirement. Get written confirmation from the city before you commit.
Can I use a pre-approved ADU plan from California or a template to speed up the process?
Yes. California has published state-approved ADU prototype plans via the California Building Standards Commission (available free at https://bsc.ca.gov/media/bsc-approved-accessory-dwelling-unit-plans). San Jose accepts these plans and fast-tracks their review (plan review time can drop from 4–5 weeks to 2–3 weeks because the structural and fire-code compliance is already vetted at the state level). If you use a state-approved plan, ensure it matches your lot size, soil conditions, and climate zone (San Jose is 3B/3C coast, 5B/6B foothills). You'll still need to customize the site plan to show your lot setbacks, utilities, and any geotechnical requirements, but the architectural and structural drawings are done. This approach saves $3,000–$5,000 in architect fees and 2–3 weeks in review.
What's the difference between a junior ADU, a detached ADU, and an above-garage ADU?
A junior ADU (CA Government Code 66411.7) is an interior remodel of an existing room or garage space, max 750 sq ft, with its own entrance and kitchen, but no footprint expansion. It's the fastest and cheapest path: no foundation work, no exterior addition, no setback recalc. Typical permit time: 3–4 weeks, cost $1,200–$2,000. A detached ADU is a new, freestanding structure in the rear yard or side yard, min 5-ft setback from property lines, no maximum square footage (though practical limits are 600–800 sq ft due to lot size). Requires full building inspection, foundation design, geotechnical review if needed. Typical permit time: 5–7 weeks, cost $2,200–$3,500. An above-garage ADU adds a second story over an existing attached garage, requiring structural reinforcement of the existing garage, new roof, new MEP. Fastest permit of the two (no new foundation), but requires careful structural review. Typical permit time: 6–7 weeks, cost $2,600–$3,800. Choose based on your lot size: under 2,500 sq ft, go junior ADU or above-garage. 2,500–4,000 sq ft, consider detached. Over 4,000 sq ft, detached is easiest.
Do I need a geotechnical report for my ADU in San Jose?
Depends on your location. If your lot is in a mapped liquefaction zone or Bay Mud area (most lots south of downtown San Jose, near the Bay, or in low-lying areas), yes — you'll need a Phase I ESA + liquefaction assessment (cost: $1,500–$2,500). The city's GIS mapping tool (searchable online) shows hazard zones. If you're in the foothills (Santa Teresa, Morgan Hill, Los Altos Hills) on stable, granitic soil, a full geotech is unlikely unless slopes exceed 20% or soils are highly expansive (rare). Contact the city in early planning (before paying an architect) and ask: 'Does my lot address require geotechnical review for ADU?' You can also check the city's Hazard Disclosure Map online or call the Building Department directly.
How much does an ADU permit cost in San Jose, and what's included?
San Jose charges permit fees based on project valuation (estimated construction cost). For a 600-sq-ft ADU, the estimated cost is typically $90,000–$130,000 (labor + materials), and the permit fee is roughly 3.5–4.5% of that, or $3,150–$5,850. Plan review is bundled into the permit fee (no separate charge). Inspection fees (per inspection type) are also included. Other soft costs not in the permit fee: utility letters (free from PG&E/SJWATER), survey ($800–$2,000 if required), architectural/engineering drawings ($2,000–$5,000), geotechnical report ($1,500–$2,500 if required), utility upgrades (electrical $3,000–$8,000, sewer CIPP $2,000 if needed). Total soft-cost range for a straightforward project: $5,000–$12,000. For complex projects (detached with geotechnical issues, or above-garage with structural work): $15,000–$25,000. Ask the city for a preliminary fee estimate before you file — upload your site plan and unit size to the online portal, and a clerk will give you a rough quote within 1 business day.
What happens if I build an ADU without a permit?
San Jose actively enforces ADU permitting through the Planning Enforcement Division. If a neighbor reports unpermitted construction, or if the city discovers it during a property tax reassessment or real-estate transaction, you'll receive a stop-work order (fine $500–$1,500) and a demand to either (a) obtain a retroactive permit (usually impossible — the structure is already built and non-compliant), or (b) remove the unit. If you try to sell or refinance the property, the title report will flag the unpermitted unit, and buyers' lenders will refuse to fund. You'll be forced to disclose the unpermitted work under California Real Estate Disclosure law, which tanks the sale price by 10–20% (easily $50,000–$200,000 on a San Jose property). Your homeowner's insurance will also exclude any claim related to the unpermitted unit (fire, injury, theft). Bottom line: the five-figure permit cost is 10–100x cheaper than the cost of non-compliance.
Can I build an ADU if I have a mortgage, HOA, or local deed restrictions?
Mortgage: check with your lender. Some lenders view ADUs as additional income and approve readily; others treat them as increased liability and require a policy rider. Most major lenders (Chase, Wells Fargo, BoA) have ADU-friendly policies as of 2023. Check before you build. HOA: if your property is in a homeowner association, the CCRs (Covenants, Conditions & Restrictions) may prohibit ADUs or require HOA approval. San Jose's ADU law (65852.2) does NOT override HOA restrictions — state law says only that local zoning cannot block ADUs, not that HOAs cannot. If your HOA prohibits ADUs, you'll need a variance (cost: $2,000–$5,000, 4–8 week timeline). Check your CC&Rs or call the HOA board before investing in architectural drawings. Deed restrictions: older properties sometimes have deeds restricting land use to single-family only. Title companies can flag these during a title search. Like HOA restrictions, state ADU law does not override private deed covenants. If your title search reveals a restriction, you'll need to apply for a covenant modification or get a consent letter from whoever holds the covenant rights (often a historic land trust or community organization). Contact a real-estate attorney early if you suspect deed restrictions.
What's the timeline from concept to move-in for a detached ADU in San Jose?
Permit + plan review: 5–7 weeks (assume 60-day streamline window, but most detached clear by week 6). Permit issuance: 1 week. Foundation inspection: 2–4 weeks (schedule, wait for inspector, pass/fail/rework). Framing inspection: 3–4 weeks. Rough MEP (electrical, plumbing, mechanical rough-in): 2–3 weeks. Drywall/insulation: 2–3 weeks. Final MEP + building + planning sign-off: 2–3 weeks. Total construction inspection timeline: 14–20 weeks. Construction labor (9–14 weeks average for a 600-sq-ft detached unit): 12–18 weeks. If you hire a general contractor and don't encounter site issues (soil surprises, utility conflicts), expect 28–32 weeks from submission to final occupancy. If you're owner-builder or encounter soil issues requiring foundation redesign, add 4–8 weeks. Realistic estimate: 6–8 months for a straightforward detached ADU, 9–12 months if structural/geotechnical work is needed.
Can I rent out an ADU immediately after the final inspection, or must I owner-occupy?
Detached ADUs: California law waives owner-occupancy, so you can rent immediately. Garage conversions and junior ADUs: also exempt from owner-occupancy in San Jose per the city's 2022 ordinance update. Above-garage additions (footprint expansion over 750 sq ft): check with San Jose Building Department in writing before you build. State law allows cities to require owner-occupancy of the primary residence for five years if the ADU is built on an owner-occupied lot. San Jose's practice is to waive this for interior-only projects (junior ADU, garage conversion) but sometimes require it for above-garage additions. Call the city's ADU desk: (408) 535-8000, ask to speak with the ADU coordinator, and request written confirmation of your scenario. Most applicants find the city is willing to confirm in writing within 1 business day, giving you peace of mind before you file.
Do I need to hire an architect or engineer, or can I DIY the plans?
If you're building a junior ADU (interior remodel only, under 750 sq ft, no footprint expansion), San Jose may accept a homeowner's sketch if the existing structure is sound. However, the city will ask for a licensed architect's or engineer's stamp on the electrical, plumbing, and structural drawings. You cannot avoid this. Hiring a local architect or ADU specialist: $2,000–$5,000 (drawings only, no permit consulting). Hiring a permit expediter (architect + plan review + submission): $3,000–$6,000. Detached ADU or above-garage addition: you MUST hire an architect or engineer. Structural design, site plan, foundation, and geotechnical coordination all require a licensed professional. Use a firm with San Jose ADU experience (ask for references). Total cost: $4,000–$8,000. Many homeowners initially balk at this cost, but it saves 4–8 weeks of rejected submissions and rework. The ROI is fast.