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Can I build an ADU in Lafayette, California?

Lafayette, Contra Costa County · Ordinances checked 2026-10-05 · Reviewed · 19 cited sections

Allowed with a permit

Yes. Lafayette allows ADUs on single-family lots: a detached ADU up to 800 sq ft (16 ft tall, 4-ft side/rear setbacks) or a conversion inside the house needs only a building permit, and larger units up to 1,200 sq ft get a ministerial ADU permit within 60 days. ADUs have no owner-occupancy requirement but can't be rented for under 30 days.

Detached ADU with building permit onlyUp to 800 sq ft [2]
Side/rear setback (new ADU)4 feet [3]
Max height, detached16 ft (Class A/B); 17 ft (Class C) [4]
Max height, attached25 ft or zone limit, whichever is lower [5]
Max size (Class C ADU permit)1,200 sq ft [6]
Junior ADU max size500 sq ft [18]
Owner-occupancyNot required for ADUs; required for JADUs [8]
Parking1 space if separate bedroom; none for studios or near transit [10]
City decision deadline60 days [13]
Minimum rental term30 days [14]
No impact feesADUs under 750 sq ft [15]

Three classes of ADU

Lafayette sorts ADUs into Class A, B and C (Municipal Code Title 6, Ch. 6-5, Art. 3). Class A and Class B units need only a building permit [1]; Class C units need a ministerial ADU permit, decided without a hearing [12], and the city must act within 60 days of a complete application [13].

  • Class A (new detached): one detached ADU on a single-family lot (plus a JADU) if it is 800 sq ft or smaller [2], has 4-foot side and rear setbacks [3], and is no taller than 16 feet [4].
  • Class B (conversion): one ADU and one JADU inside the house, a proposed house, or an existing accessory building (plus up to 150 sq ft for access) [16].
  • Class C (everything else): up to 1,200 sq ft detached or attached [6]; an attached unit is also capped at 50% of the existing home's floor area, but these limits can never force a unit below 800 sq ft [7]. Side and rear setbacks are at most 4 feet [17]; front setbacks run 20 to 50 feet depending on the zone. Detached Class C units may be 17 feet tall [4]; attached ADUs up to 25 feet or the zone limit, whichever is lower [5]. Class C units must match the house's materials and colors, use shielded lighting, and meet creek setbacks.

A junior ADU (JADU) is up to 500 sq ft inside the house [18].

Owner-occupancy and rentals

ADUs created on or after January 1, 2020 have no owner-occupancy requirement [8]. The code requires the owner to live on site for every JADU [9]; state law now allows that requirement only for a JADU that shares a bathroom, so state law may override this provision for JADUs with their own bathroom. ADUs and JADUs can't be rented for less than 30 days [14], and a deed restriction must be recorded before occupancy [19].

Coming state change

Lafayette's Class A route covers one new detached ADU per single-family lot [2]. Starting January 1, 2027, state law (AB 956) will require cities to approve two new detached ADUs on a single-family lot ministerially, so that limit may be overridden from that date.

Parking and fees

A Class C ADU with a separate bedroom needs one off-street space; studios need none [10]. No parking is required within half a mile walking distance of public transit [11], for conversions, or to replace a converted garage. ADUs under 750 sq ft pay no impact fees [15].

See how Lafayette compares with 8+ other California towns on accessory dwelling units (adus) →

Next steps

  1. Decide which class fits: a conversion (Class B) or a detached unit of 800 sq ft or less with 4-ft setbacks (Class A) needs only a building permit; anything larger needs a Class C ADU permit from the Lafayette Planning & Building Department (see the city website).
  2. Check your zone's front setback and whether your lot is near a creek or in the Hillside Overlay District before drawing plans.
  3. Submit plans for the building permit (building permits are issued through Contra Costa County on the city's behalf); the city must act on a complete ADU application within 60 days.
  4. Record the city's ADU deed restriction (no separate sale, no rentals under 30 days) before the certificate of occupancy.

Common questions

Are ADUs allowed in Lafayette, California?
Yes. Lafayette allows ADUs on single-family lots. A detached ADU up to 800 sq ft or a conversion inside the house needs only a building permit, and larger units up to 1,200 sq ft get a ministerial ADU permit within 60 days.
How tall can a detached ADU be in Lafayette, California?
A detached ADU can be 16 ft tall (17 ft for Class C), with 4-ft side and rear setbacks.
Do I have to live on the property to have an ADU in Lafayette, California?
No. ADUs have no owner-occupancy requirement, though junior ADUs do.
Can I rent my ADU short term in Lafayette, California?
No. ADUs can't be rented for under 30 days.

California's statewide ADU law

California's ADU law (Gov. Code §§66310–66342, recodified from §65852.2; latest amendments effective January 1, 2026) overrides conflicting city rules, including in charter cities. Cities must approve ADUs ministerially (no hearing) within 60 days of a complete application, or the permit is deemed approved.

What cities cannot require or do:

  • Owner-occupancy for an ADU.
  • A minimum lot size.
  • Side or rear setbacks over 4 feet for a new ADU, or any setback for a converted existing structure.
  • Size, lot coverage or floor-area rules that block an ADU of at least 800 sq ft. Size caps can't be under 850 sq ft (1,000 for 2+ bedrooms).
  • Parking within half a mile walking distance of public transit, or replacement parking for a garage converted to an ADU.
  • Impact fees on ADUs of 750 sq ft or less.

By right on a single-family lot: one converted ADU plus one junior ADU (JADU, up to 500 sq ft inside the house), plus one new detached ADU (up to 800 sq ft, 16 ft tall). Owner-occupancy may be required only for a JADU that shares a bathroom.

Short-term rentals: cities may bar ADU rentals under 30 days, and must for by-right ADUs, JADUs and SB 9 units.

Coming January 1, 2027: AB 956 raises the by-right count to two new detached ADUs per single-family lot.

SB 9 (§§65852.21, 66411.7) allows two homes on a single-family lot, or a split into two lots of at least 1,200 sq ft (with a 3-year owner-occupancy affidavit).

State sources: Gov. Code §66314 (ADU ordinance standards) · Gov. Code §66315 (no owner-occupancy requirement) · Gov. Code §66317 (ministerial review, 60-day deadline) · Gov. Code §66321 (size, setback and height limits on local rules) · Gov. Code §66322 (parking exemptions) · Gov. Code §66323 (by-right ADUs and JADUs) · Gov. Code §66333 (junior ADUs) · Gov. Code §66311.5 (impact fees) · AB 956 (2026), Stats. 2026, ch. 791 · Gov. Code §65852.21 (SB 9 two-unit projects) · Gov. Code §66411.7 (SB 9 urban lot splits) · HCD, Accessory Dwelling Units (ADU Handbook, updated March 2026)

What the ordinance says

Exact text from Lafayette's published ordinances. Section numbers are as printed in the source.

  1. Sec. 6-564 Class A ADUs, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    If an ADU or JADU complies with each of the general requirements in Section 6-563 above, and the specific requirements of either subsection (a) or (b) below, it is a Class A ADU and is allowed with only a building permit in the following scenarios:
  2. Sec. 6-564(a)(2), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    The total floor area is 800 square feet or smaller.
  3. Sec. 6-564(a)(1), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    The side- and rear-yard setbacks are at least four feet.
  4. Sec. 6-563(b)(1) Height, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    Except as otherwise provided by subsections b(2) and b(3) below, a detached Class A or Class B ADU created on a lot with an existing or proposed single family or multifamily dwelling unit may not exceed 16 feet in height. Except as otherwise provided by subsections b(2) and b(3) below, a detached Class C ADU may not exceed 17 feet in height.
  5. Sec. 6-563(b)(4), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    An ADU that is attached to the primary dwelling may not exceed 25 feet in height or the height limitation imposed by the underlying zone that applies to the primary dwelling, whichever is lower.
  6. Sec. 6-566(a)(1) Class C maximum unit size, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    The maximum size of a detached or attached ADU subject to this section is 1,200 square feet of floor area.
  7. Sec. 6-566(a)(2), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    An attached ADU that is created on a lot with an existing primary residence is further limited to 50 percent of the floor area of the existing primary residence except as permitted by subsection (a)(3) below.
  8. Sec. 6-563(i)(1) Owner Occupancy, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    ADUs created under this article on or after January 1, 2020 are not subject to an owner-occupancy requirement.
  9. Sec. 6-563(i)(2), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    As required by state law, all JADUs are subject to an owner-occupancy requirement. A natural person with legal or equitable title to the property must reside on the property, in either the primary residence or JADU, as the person's legal domicile and permanent residence.
  10. Sec. 6-566(f)(1) Parking, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    Generally, one off-street parking space is required for each ADU subject to this section that has one or more separate bedrooms. Off-street parking is not required for ADUs without separate bedrooms (studio).
  11. Sec. 6-566(f)(2)(A), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    The ADU is located within one-half mile walking distance of public transit, as defined Section 6-561(r) above.
  12. Sec. 6-562(a) Process and timing, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    An ADU permit is considered and approved ministerially, without discretionary review or a hearing.
  13. Sec. 6-562(b), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    The city must approve or deny an application to create an ADU or JADU within 60 days from the date that the city receives a completed application.
  14. Sec. 6-563(f) Rental Term, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    No ADU or JADU may be rented for a term that is shorter than 30 days. This prohibition applies regardless of when the ADU or JADU was created.
  15. Sec. 6-567(a) Impact fees, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    No impact fee is required for an ADU that is less than 750 square feet in floor area.
  16. Sec. 6-565(a) Class B ADUs (converted on single-family lot), Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    Up to one ADU as described in this subsection (a) and one JADU are permitted on a lot with a proposed or existing single-family dwelling on it, either individually or together, where it/they:
  17. Sec. 6-566(b)(1) Setbacks, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    A setback of no more than four feet from the side and rear lot lines shall be required; except no setback shall be required for an ADU that is constructed in the same location and to the same dimensions as an existing structure.
  18. Sec. 6-561(j)(1) JADU definition, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    It is no more than 500 square feet in floor area.
  19. Sec. 6-563(j) Deed Restriction, Municipal Code Title 6 Ch. 6-5 General Provisions (Art. 3 Accessory Dwelling Units; Art. 6 Small Farm Animals; 6-511 sight obstructions; 6-517/6-526 accessory structures in yards; 6-523/6-524 livestock and animal structures)
    Prior to issuance of a certificate of occupancy for an ADU or JADU, a deed restriction must be recorded against the title of the property in the county recorder's office and a copy filed with the zoning administrator.
This page summarizes Lafayette's posted ordinances as of 2026-10-05. Ordinances are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with City of Lafayette Planning & Building / Code Enforcement, 3675 Mt. Diablo Blvd., Suite 210 (building permits & building-code violations handled by Contra Costa County Building Inspection Dept., Lamorinda office 925-299-0263; County code enforcement 925-655-2710) (925-284-1968 (Code Enforcement); Planning 925-284-1976) before you build. Spot an error?