Can I Build an ADU in Santa Clara?

Yes — by right

ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.

1 detached ADU + 1 converted ADU + 1 JADU

Santa Clara allows one detached ADU, one converted (existing-space) ADU, and one JADU on a single-family lot, and all three may be combined on the same lot.

Conversion ADUs (≥1, up to 25% of units) + up to 8 detached

Conversions of non-livable space (at least 1, or up to 25% of existing units) plus up to 8 detached ADUs on a lot with existing multifamily — never exceeding the number of existing units. JADUs are single-family only.

Allowed

Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).

1,200 sq ft

1,000 sq ft on parcels ≤5,500 sq ft; 1,200 sq ft on larger parcels. The 800 sq ft state ADU (4-ft setbacks, 18-ft height) is allowed by right regardless of lot size or coverage/FAR limits.

1,000 sq ft or 50% of the main dwelling (minimum 800 sq ft always allowed), whichever is less

800 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).

500 sq ft

18 ft

18 ft for a 1-story detached ADU (also the floor for a detached ADU within ½ mi of major transit or on a multifamily lot); up to 25 ft for a 1.5-story detached ADU (with added standards) or a 2-story attached ADU.

4 ft

A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.

4 ft

4 ft rear setback for a one-story ADU; multi-story ADU elements must be set back 15 ft from the rear lot line.

No front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone

None required

No statewide separation requirement between the ADU and the primary dwelling.

None

Santa Clara requires no parking for any ADU or JADU, and no replacement parking for garage conversions.

Yes — 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.

Not required

When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.

Ministerial (by right)

No public hearing or discretionary design review for a qualifying ADU.

60 days

The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.

Only for a JADU

No owner-occupancy for ADUs; a JADU requires the owner to occupy the JADU or the main dwelling (unless owned by a government agency, land trust, or housing organization).

Waived 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.

Building permit, Zoning Clearance (ministerial)

Ministerial Zoning Clearance plus a building permit; discretionary Architectural Review is triggered only if a project does not meet the objective ministerial standards.