California ADU rules · Santa Clara County
Can I Build an ADU in Milpitas?
Yes — you can build an ADU in Milpitas. California's statewide ADU law requires every city, including Milpitas, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
CA state law1 ADU + 1 JADU
At least one ADU and one JADU per single-family lot (a conversion ADU may also be possible).
Units on a multifamily lot
Local ruleconversions (>=1 or 25% of units) + up to 2 detached
Local cap of 2 detached ADUs on multifamily lots, less than state default of 8.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,000 sq ft
Detached ADU max is 850 sq ft (studio/1-bed) or 1,000 sq ft (2-bed) with Minor SDP; 1,200 sq ft in Hillside district.
Max attached ADU size
Local rule850 (studio/1-bed), 1,000 (2-bed), or 50% of primary, whichever is less; never less than 800 if 4-ft setbacks met; 1,200 in Hillside
Attached ADU max mirrors detached; 1,200 sq ft in Hillside.
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule20 ft
Detached ADU: 16 ft standard, 18 ft near transit/multifamily, up to 20 ft to match roof pitch; attached ADU up to 25 ft or zoning limit.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
Local rule25 ft for ADUs requiring Minor SDP; cannot preclude 800 sq ft ADU with 4-ft setbacks
25 ft front setback for some ADUs, but not allowed to block a by-right 800 sq ft ADU.
Separation from main house
Local rule6 ft
Detached ADU must be at least 6 ft from rear wall of primary dwelling.
Parking
Parking required
Local ruleUp to 1 space
1 off-street space per ADU unless exempt; JADUs require no parking.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
Local ruleBuilding permit, Minor Site Development Permit (for some ADUs)
Minor SDP required for ADUs exceeding by-right standards.
Milpitas-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Hillside Combining District
Allows up to 1,200 sq ft ADUs (attached or detached)
Milpitas limits detached ADUs on multifamily lots to 2 and requires a 6-foot separation from the primary dwelling. Larger ADUs (up to 1,200 sq ft) are allowed in the Hillside district.
Frequently asked questions
Can I build an ADU in Milpitas?
Yes. California's statewide ADU law requires Milpitas to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Milpitas?
A detached ADU of at least 1,000 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Milpitas?
Side and rear setbacks are limited to 4 ft. 25 ft for ADUs requiring Minor SDP; cannot preclude 800 sq ft ADU with 4-ft setbacks.
Is parking required for an ADU in Milpitas?
Up to 1 space. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Milpitas?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Milpitas?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Milpitas Municipal Code § XI-10-13.08 (amended 2023)
- Milpitas Code § XI-10-13.08(D)(1)(c)-(d)
- Milpitas Code § XI-10-13.08(F)(1)(a)-(c)
- Milpitas Code § XI-10-13.08(E)(3)(a)-(e)
- Milpitas Code § XI-10-13.08(F)(2)(b)
- Milpitas Code § XI-10-13.08(F)(3)
- Milpitas Code § XI-10-13.08(F)(7)(a)-(b)
- Milpitas Code § XI-10-13.08(D)(2)
- Milpitas Code § XI-10-13.08(F)(1)(c)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66315 (owner-occupancy)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of Milpitas's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Milpitas Planning before relying on it.
Will an ADU work on your Milpitas lot?
Ask GoCodebook about your address and get the size, setback, parking and permit rules that actually apply to your parcel — with the exact citation.
Check my parcel free