Cupertino, CA Accessory Structures: ADU Rules (2026)
ADU rules in Cupertino, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Max ADUs per SFR lot
- Three, any combination
- Detached ADU height
- 18 ft (20 ft near transit)
- Attached ADU height
- 25 ft or primary height, lower
- Minimum setback
- 4 ft from side/rear lot lines
- ADU parking required
- None
- Governing citation
- CMC § 19.112.020
Summary
Cupertino allows accessory dwelling units on any residential or mixed-use residential lot with an existing dwelling, and ADUs never count toward the lot's maximum density. Under Municipal Code Section 19.112.020, ADUs must still meet the underlying zone's lot coverage, floor area ratio, height, setback and landscape standards unless Chapter 19.112 itself modifies them.
Accessory dwelling units are permitted on lots within any residential or mixed-use residential zoning district. The lot must have an existing single family dwelling unit or if zoned multi-family or mixed use residential, at least one residential unit. If the lot is vacant, an accessory dwelling unit may only be proposed in conjunction with the development of at least one residential unit. Notwithstanding the underlying zoning, an accessory dwelling unit developed pursuant to this chapter does not cause the lot upon which it is located to exceed its maximum allowable density on the lot. ... Accessory dwelling units, except those pursuant to Government Code Section 66323, must comply with the site development regulations and guideline specified in those zoning districts for dwelling units, including but not limited to: lot coverage; floor area ratio; height; setbacks; landscape; the regulations contained in this chapter; Chapter 19.100, Accessory Structures/Buildings; and Chapter 19.124, Parking; except as those standards are modified by this chapter.
Full Breakdown
112 permits accessory dwelling units on any residential, agricultural residential, or mixed-use residential lot that already has a single-family dwelling, or at least one unit if the lot is zoned multi-family or mixed-use. A vacant lot can only add an ADU alongside a new primary residential unit. Notwithstanding the underlying zoning, an ADU built under this chapter never pushes the lot over its maximum allowable density. 112 modifies those standards. 030A, a single-family lot can hold up to three ADUs in any combination of attached, detached, converted-space, or junior ADU.
Detached units max out at 18 feet in height (20 feet within a half mile of a major transit stop, to match a primary dwelling's roof pitch), while an attached ADU is capped at 25 feet or the primary dwelling's height, whichever is lower. 100's accessory-structure setback and height standards. No off-street parking is required for a streamlined ADU, and independent outdoor access must be provided without passing through the primary dwelling.
Violations & Fines
The City may not issue a certificate of occupancy for an ADU before the primary dwelling has its own certificate of occupancy, under Section 19.112.020. Beyond that sequencing rule, an ADU that departs from the site development standards in Chapter 19.100 or 19.124 is treated as an ordinary zoning violation, referable to the City's code enforcement and administrative citation process in Chapters 1.09 and 1.10.
Frequently Asked Questions
Does a Cupertino ADU need off-street parking?
How many accessory dwelling units can I build on one lot?
Can I sell my ADU separately from the house?
Sources & Official References
Other rules in Cupertino
How Cupertino compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Cupertino to another location·View the California accessory structures overview
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ADU Rules in Nearby Cities
How other cities in Santa Clara County handle adu rules.