Chapter 19.112 — ACCESSORY DWELLING UNITS
Cupertino Zoning Code · 2026-06 edition · ingested 2026-07-06 · Cupertino
19.112.010 Purpose; Incorporation by Reference; Consistency with State Law. ¶
The purpose of this chapter is to promote the goal of affordable housing within the City through provision of additional housing in certain residential, agricultural residential, and
mixed-use zoning districts in a manner which minimizes adverse impacts of accessory dwelling units on neighborhoods. Unless otherwise defined in this Title, all terms used in this Chapter shall be defined and interpreted in accordance with Government Code Sections 66310-66342. In the event of a conflict between this Chapter and the requirements of State law, the requirements of State law, including the requirements of Government Code Sections 66310-66342, shall prevail.
(Ord. 20-2199, § 5 (part), 2020; Ord. 16-2159, § 8 (part), 2016; Ord. 2085, § 2 (part), 2011; Ord. 1601, Exh. A (part), 1992; Ord. 23-2254, Att. A (part), 2023; Ord. 25-2274, Att. A (§ 1), 2025; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.020 Accessory Dwelling Unit Regulations. ¶
Notwithstanding any provision of this title to the contrary:
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. No impact fees, as defined in Government Code Section 6324(c)(2), shall be imposed on any accessory dwelling unit or junior accessory dwelling unit with a gross floor area of less than 750 square feet. Impact fees imposed on accessory dwelling units greater than or equal to 750 feet shall be charged proportionally in relation to the square footage of the primary dwelling unit in compliance with Government Code Section 6324(c)(1).
Accessory dwelling units may be rented separately from the single-family dwelling or multi-family dwelling structure but may not be sold or otherwise conveyed separately from the other dwellings on the lot, except pursuant to Government Code Section 6340 – 66342. Any accessory dwelling unit, including a Junior Accessory Dwelling Unit (JADU), shall not be used as a rental for a term less than 30 days.
For JADUs, either the single-family residence or JADU must be owner-occupied, unless the owner is a governmental agency, land trust, or housing organization. Further, the owner shall record a deed restriction, expressly enforceable against future purchasers, containing the following: (a) a prohibition on the sale of the JADU separate from the single-family residence, and (b) a restriction on the size and attributes of the JADU to conform to this section.
A local agency shall not issue a certificate of occupancy for an accessory dwelling unit before the local agency issues a certificate of occupancy for the primary dwelling.
(Ord. 20-2199, § 5 (part), 2020; Ord. 17-2170, § 3, 2017; Ord. 16-2159, § 8 (part), 2016; Ord. 2085, § 2 (part), 2011; Ord. 1901, (part), 2002; Ord. 1601, Exh. A (part), 1992; Ord. 232254, Att. A (part), 2023; Ord. 25-2274, Att. A (§ 1), 2025; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.030 Site Development Regulations for Streamlined Accessory Dwelling Units &… ¶
Pursuant to California Government Code Section 66323, the City shall approve the following streamlined accessory dwelling units if the specified development standards and
use restrictions are met, as identified in:
Table 19.112.030A for single-family residential uses and
Table 19.112.030B for multi-family residential uses.
Table 19.112.030A: Site Development Regulations for Streamlined Accessory Dwelling Units and Junior Accessory Dwelling Units Associated with Single-Family Residential Uses
| Uses | ||
|---|---|---|
| Conversion of space within principal dwelling unit or accessory structures |
New Constructon Atached or Detached Accessory Dwelling Unit ≤ 800 s.f. |
|
| 1. Size of living space, exclusive of decks | ||
| a. Minimum size | 150 s.f. | |
| b. Maximum size |
No size limitaton as long as the unit: Is wholly within the space of a proposed or existng single-family dwelling or the existng space of an accessory structure, and Does not require either: An additon of more than 150 square feet to an existng accessory structure to accommodate ingress and egress only, or Any additon to an existng single-family dwelling unit. |
800 s.f. |
| 2. Number of Units | Maximum three ADUs per single-family residental lot, in any combinaton of the following: Atached ADU, Conversion of existng space ADU (whether in principal dwelling unit or existng accessory structure), Detached ADU, or Junior ADU |
|
| 3. Setbacks | Per the underlying zoning district except that if the existng structures do not meet these standards, the side and rear setbacks shall be sufcient for fre safety and life safety. |
At least four feet from the rear and side lot lines. An applicant alternately may elect to follow the setback standards for accessory structures in Chapter 19.100. |
| 4. Height | The conversion shall not change the height of the existng structure. |
18 feet for detached ADU If accessory dwelling unit |
| is atached to principal dwelling, 25 feet or the height limitatons applicable to the principal dwelling, whichever is lower. An applicant alternatvely may elect to follow the height standards for accessory structures in Chapter 19.100. |
||
| --- | --- | --- |
| 5. Second-story accessory dwelling unit |
Allowed if the unit is a conversion of existng second story porton of the principal dwelling unit. |
Allowed |
| 6. Parking for accessory dwelling unit |
None | None |
| 7. Direct outside access |
Independent outdoor access must be provided without going through the principal dwelling unit. |
|
| 8. Separaton from principal dwelling unit |
The conversion must result in an independent unit. With the excepton of a JADU that has a shared bathroom with the principal dwelling unit, no interior doors or other connectons between the units are permited. |
Detached from principal dwelling unit |
- An additional two feet in height ( from 18 to 20 feet) for ADUs within one half mile of a major transit stop or a high quality transit corridor is permitted to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.
Table 19.112.030B: Site Development Regulations for Streamlined Accessory Dwelling Units Associated with Existing Multi-Family Residential Uses
| Conversion of interior space and JADUs within multfamily dwelling structures |
Detached, and Atached New Constructon |
||
|---|---|---|---|
| 1. | Locaton | Conversion of space within existng dwelling structures that is not used as livable space (e.g. existng units) including, but not limited to, storage rooms, boiler rooms, passageways, atcs, basements, or garages, as long as the unit meets building standards for dwellings. JADUs permited only in duplexes |
Must be detached from the mult-family dwelling structure(s) other than for duplex zoned propertes, except atached ADUs are allowed for duplex zoned propertes. |
| 2. | Maximum Number of Units | ||
| a. Multfamily developments |
i. The greater of: | ii. On a lot with an existng mult-family |
|
| other than duplex zoned propertes |
25 percent of the existng number of primary dwelling units, or One accessory dwelling unit |
dwelling, the lesser of: Eight detached accessory dwelling units and the number of existng mult- family units on the lot. iii. On a lot with a proposed multfamily dwelling, not more than two detached ADUs. |
|
| --- | --- | --- | --- |
| b. Duplex zoned propertes |
Up to a maximum of two accessory dwelling units in any combinaton of the following: Atached ADU, Conversion of existng space ADU (whether in principal dwelling unit or existng accessory structure), Detached ADU, or Junior ADU |
||
| 3. | Minimum Size | 150 s.f. | |
| 4. | Maximum Size | No size limitaton For duplex zoned propertes, atached ADUs are limited to 800 s.f. |
|
| Conversion of interior space and JADUs within multfamily dwelling structures |
Detached, and Atached New Constructon |
||
| 5. | Setbacks | The accessory dwelling unit shall not increase the size of the existng structure. |
a. Located at least four feet from the side and rear lot lines. b. An applicant alternately may elect to follow the setback and height standards for accessory structures in Chapter 19.100. |
| 6. | Height | The accessory dwelling unit shall not increase the size of the existng structure. |
a. 18 feet1 b. An applicant alternatvely may elect to follow the setback and height standards for accessory structures in Chapter 19.100. |
| 7. | Separaton from principal dwelling units |
The conversion must result in an independent unit. No interior doors or other connectons between the units are permited. |
Detached from principal dwelling units. |
- An additional two feet in height (from 18 to 20 feet) for ADUs within one half mile of a major transit stop or a high-quality transit corridor is permitted to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.
(Ord. 20-2199, § 5 (part), 2020; Ord. 17-2170, § 4, 2018; Ord. 17-2165, § 12, 2017; Ord. 16-2159, § 8 (part), 2016; Ord. 2085, § 2 (part), 2011; Ord. 23-2254, Att. A (part), 2023; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.040 Site Development Regulations for Non-Streamlined Accessory Dwelling Units.
This section shall govern applications for ADUs and JADUs that do not qualify for approval under Section 19.112.030 or Government Code section 66323 and for which the city may impose local standards pursuant to Government Code section 66314 - 66322. Nothing in this section shall be interpreted to prohibit an ADU of up to 800 square feet, at the heights stated in Section 19.112.030(A) and .030(B), with a four-foot side and rear setbacks.
The Development Standards for units governed by this section are provided in Section 19.112.040. These regulations do not limit the height of existing structures converted into ADU/JADUs unless the envelope of the building is proposed to be modified beyond any existing legal, non-conforming condition.
Table 19.112.040: Site Development Regulations for Non-Streamlined Accessory Dwelling Units
Created by New Construction and/or Additions to the Principal Dwelling Unit
| Atached> 800 s.f. | Detached> 800 s.f. | |||||
|---|---|---|---|---|---|---|
| A. | Number of Units | 1. A maximum of three ADUs per single-family lot in any combinaton of the following, subject to the underlying zoning standards for lot coverage, foor area, open space, and setback: No more than one atached ADU No more than one conversion of existng space ADU (whether in principal dwelling unit or existng accessory structure), No more than one detached ADU, or o No more than one Junior ADU 2. Nothing in this Secton shall permit the development of more than three ADUs or Junior ADUs on any single- family lot. Non-streamlined ADU provisions cannot be combined with streamlined provisions to add more than a total of three ADUs. |
||||
| B. | Size of living space, exclusive of decks | |||||
| 1. Minimum size | 150 s.f. | |||||
| 2. Maximum size | Studios/one-bedroom unit – 850 s.f.; two or more-bedroom unit – 1,000 s.f.; and Atached accessory dwelling units shall not exceed 50% of the existng primary dwelling Lot coverage, foor area, and open space standards per underlying zoning apply to ADUs grater than 800 s.f. See Table 19.112.030 A for requirements related to ADUs less than or equal to 800 s.f. |
|||||
| C. | Setbacks1 | Per the underlying zoning district, except the required side and rear setbacks are modifed to four feet. |
The proposed structure must comply with the setback standards for accessory structures in Chapter 19.100, except the street side setbacks are modifed to four feet. |
|||
| Atached > 800 s.f. | Detached > 800 s.f. | |||||
| D. | Height | 25 feet of the height limitatons applicable to the principal dwelling, whichever is lower. |
The proposed structure must comply with the height standards for accessory structures in Chapter 19.100, except that a maximum height of 18 feet is allowed within half a mile of a major transit stop or transit corridor. |
|||
| Atached> 800 s.f. | ||||||
| --- | --- | --- | --- | --- | --- | --- |
| E. | Second-story accessory dwelling units |
Allowed within half a mile of a major transit stop or transit corridor. |
||||
| F. | Parking | |||||
| 1. Parking for accessory dwelling unit |
One additonal of-street parking space shall be provided, if the principal dwelling unit has less than the minimum of-street parking spaces for the applicable residental zoning district in which it is located, as required in Chapter 19.124, and none if the accessory dwelling unit meets one of the following requirements: Located within one-half (1/2) mile of a public transit stop; or Located within one block of a car share vehicle pick-up locaton; or Located in an architecturally and historically signifcant historic district; or The occupant of the unit is not allowed/ofered a required on-street parking permit; or Is part of the proposed or existng primary residence or an accessory structure or When a permit applicaton for an accessory dwelling unit is submited with a permit applicaton to create a new single-family dwelling on the same lot provided that the accessory dwelling unit or the parcel satsfes any other criteria listed above. |
|||||
| 2. Demoliton or conversion of existng covered, uncovered or enclosed parking spaces for an accessory dwelling unit |
No replacement parking spaces are required. | |||||
| Atached > 800 s.f. | Detached > 800 s.f. | |||||
| G. | Direct outside access | Independent outdoor access must be provided without going through the principal dwelling unit. |
||||
| H. | Screening from public street |
All access to accessory dwelling units shall be on a diferent wall plane than the access to the principal dwelling unit. |
||||
| I. | Structure Design | Shall match the exterior and roofng materials, window style, exterior lightng and exterior colors of the principal structure. Shall meet the design standards when located within any one of the following zoning districts: Planned Development (P) Eichler (R1-e) Monta Vista Design Guidelines Residental Hillside (RHS) Single Family Residental District with Semi-Rural Characteristcs (R1- a) |
||||
| Atached> 800 s.f. | Detached> 800 s.f. | |||||
| --- | --- | --- | --- | --- | --- | --- |
| J. | Separaton from principal dwelling unit |
The ADU must be an independent unit. No interior doors or other connectons between the ADU and the principal dwelling unit are permited. |
Detached from principal dwelling unit. |
|||
| 1.No setback is required for an accessory dwelling unit located within existng living area or an existng accessory structure, or an accessory dwelling unit that replaces an existng structure and is located in the same locaton and to the same dimensions as the structure being replaced. |
(Ord. 20-2199, § 5 (part), 2020; Ord. 23-2254, Att. A (part), 2023; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.050 Review Process. ¶
Applications for accessory dwelling units conforming to the requirements of this chapter shall be reviewed ministerially without discretionary review and must be approved or denied within the time frame specified in Government Code Section 66317.
Nonconforming zoning conditions, building code violations or unpermitted structures:
The correction of nonconforming zoning conditions (as defined in Government Code Section 66313) shall not be required as a condition of approval of a permit for the creation of an ADU or a JADU.
A permit for an ADU or a JADU will not be denied due to the correction of nonconforming zoning conditions, building code violations, or other unpermitted structures that do not present a threat to public health and safety and that are not affected by the construction of the ADU or JADU.
Unpermitted ADU or JADU: Any ADU created within the City shall comply with all applicable provisions of the Municipal Code and state law, and must obtain a building permit confirming compliance with all requirements, except that:
A permit to legalize an unpermitted ADU or JADU that was constructed before January 1, 2020 may not be denied, if denial is based on either of the following grounds:
The ADU or JADU violates applicable building standards, or
The ADU or JADU does not comply with state ADU or JADU law (Government Code Section 66313-66339) or this chapter.
Notwithstanding the above, a permit to legalize an unpermitted ADU or JADU that was constructed before January 1, 2020 may be denied, if the City makes a finding that correcting violations of applicable building standards, state ADU/JADU law, and/or this municipal code, is necessary to comply with the standards specified in California Health and Safety Code section 17920.3.
Notwithstanding subsection (C)(1) or (C)(2) above, a building that is deemed to be substandard in accordance with California Health and Safety Code Section 17920.3 shall not be permitted.
(Ord. 20-2199, § 5 (part), 2020; Ord. 16-2159, § 8 (part), 2016; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.060 Accessory Dwelling Units Prohibited on Certain Lots. ¶
Notwithstanding Government Code Section 66313 - 66339 or any provision of this Chapter, no accessory dwelling unit or a junior accessory dwelling unit shall be permitted on any lot in single-family residence district (R-1 or RHS) if an urban lot split has been approved pursuant
to Section 18.12.70 and one or more residential unit(s) have been approved for construction pursuant to Section 19.28.150 or 19.40.090 (Government Code Section 65852.21).
(Ord. 22-2246, § III (part), 2022; Ord. 22-2238, § 3.14, 2022; Ord. 21-2235, § 3.14, 2021; Ord. 25-2274, Att. A (§ 1), 2025)
19.112.070 Enforcement. ¶
Violations of this Chapter shall be enforced as authorized by this Municipal Code and applicable provisions of state law.
Enforcement of Building Code standards: In enforcing building standards pursuant to Article 1 (commencing with Section 17960) of Chapter 5 of Part 1.5 of Division 13 of the Health and Safety Code for an ADU described below, a local agency, upon request of an owner of an ADU for a delay in enforcement, shall delay enforcement of a building standard, subject to compliance with Section 17980.12 of the Health and Safety Code:
The ADU was built before January 1, 2020.
The ADU was built on or after January 1, 2020, and at the time the ADU was built, the City had a noncompliant ADU ordinance, but the ordinance is compliant at the time the request is made.
(Ord. 25-2274, Att. A (§ 1), 2025)