Town Permit Guide

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Can I build an ADU in Tiburon, California?

Tiburon, Marin County · Ordinances checked 2026-10-05 · Reviewed · 11 cited sections

Allowed with a permit

Yes. Tiburon allows ADUs in every residential zone through a ministerial building permit decided within 60 days, with no hearing. A typical detached ADU can be up to 850 sq ft (one bedroom, lot under 10,000 sq ft) or 1,000 sq ft (two or more bedrooms, or a larger lot) and 16 feet tall, with 4-foot side and rear setbacks. A junior ADU of up to 500 sq ft inside the house is also allowed.

Zones allowedAll residential zones (ministerial permit, "MP") [1]
Approval processMinisterial building permit, decided within 60 days, no public hearing [2]
Max size, 1 bedroom on lot under 10,000 sq ft850 sq ft [3]
Max size, 2+ bedrooms or lot over 10,000 sq ft1,000 sq ft [4]
Side and rear setbacks4 feet [5]
Max height, detached ADU16 feet (18 ft near a major transit stop, plus 2 ft for matching roof pitch) [6]
Max height, attached ADU25 feet [7]
Parking1 off-street space, unless an exception applies [8]
JADU max size500 sq ft, inside the house [9]
Minimum rental term30 consecutive days [11]

Where and how

Accessory dwelling units and junior ADUs are a ministerial-permit use in every residential zone, including R-1, RO, R-2 and the planned-development zones [1]. Applications go to the Community Development Director as a building permit, with no discretionary review or hearing, and must be approved or denied within 60 days or they are deemed approved [2]. Neighbors within 100 feet get a courtesy notice before the decision. Other exterior work beyond the ADU itself (and roof decks) goes through regular site plan and architectural review. Starting January 1, 2027, state law (AB 956) will require cities to approve two new detached ADUs on a single-family lot; Tiburon's code doesn't reflect that yet.

Size, setbacks and height

  • A new attached or detached ADU is capped at 850 sq ft with one bedroom on a lot under 10,000 sq ft [3], and 1,000 sq ft with more than one bedroom or on a lot over 10,000 sq ft [4]. An attached ADU can't exceed 50% of the existing house, but the town guarantees an 800 sq ft unit. Larger ADUs need site plan and architectural review.
  • Side and rear setbacks are 4 feet, and the front setback yields if needed to fit an 800 sq ft ADU [5]. Converted existing space needs no setback.
  • Detached ADUs are limited to 16 feet, or 18 feet near a major transit stop [6]. Attached ADUs can be 25 feet [7].
  • An ADU must sit at least 10 feet from the top of any creek bank on the lot. Colors and materials must match the main house when the ADU is over 800 sq ft.

Parking

One off-street space is required [8], but none is needed within half a mile walking distance of public transit, for ADUs inside the house or an existing accessory structure, and in several other cases. A garage converted or demolished for an ADU doesn't have to be replaced.

Junior ADUs

A JADU is up to 500 sq ft inside the single-family home, with an efficiency kitchen; one per lot [9]. Tiburon requires that either the main house or the JADU be owner-occupied [10]. State law may override that provision where the JADU has its own bathroom, since California now allows owner-occupancy only for a JADU that shares sanitation facilities.

Renting

The ADU or JADU may be rented separately but not for less than 30 consecutive days or as a vacation rental [11]. The ADU can't be sold separately except under state-law conditions.

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

Next steps

  1. Check your zone and lot size on the Tiburon zoning map, and whether you are within half a mile of public transit (no parking needed).
  2. Prepare plans showing size, height, setbacks, parking and a separate exterior entrance, plus a sanitary district capacity letter.
  3. Submit a building permit application for the ADU or JADU to Community Development (Building Division), 1505 Tiburon Boulevard, 415-435-7380.
  4. For a JADU, be ready to record a deed restriction against separate sale and confirm owner occupancy requirements with staff.

Common questions

Are ADUs allowed in Tiburon, California?
Yes. Tiburon allows ADUs in every residential zone through a ministerial building permit decided within 60 days, with no hearing.
How big can an ADU be in Tiburon, California?
A typical detached ADU can be up to 850 sq ft (one bedroom, lot under 10,000 sq ft) or 1,000 sq ft (two or more bedrooms, or a larger lot) and 16 feet tall, with 4-foot side and rear setbacks.
Is a junior ADU allowed in Tiburon, California?
Yes. A junior ADU of up to 500 sq ft inside the house is allowed.
Can I rent my ADU short term in Tiburon, California?
No. The minimum rental term is 30 consecutive days, with no vacation rental use.

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 Tiburon's published ordinances. Section numbers are as printed in the source.

  1. Sec. 16-21.030, Table 2-1, Municipal Code Ch. 16 Sec. 16-21 Residential Zones (allowed uses and development standards), p. 1
    Accessory dwelling unit /Junior accessory dwelling unit (5) MP MP MP MP MP MP MP MP
  2. Sec. 16-52.100(B)(3), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    Building permit applications for ADUs shall be acted upon by the director of community development or designee ministerially without discretionary review or a public hearing. The building permit application shall be approved or denied in writing within sixty days from receipt of a completed application and if not acted upon within that timeline the application shall be deemed approved.
  3. Sec. 16-52.100(C)(2)(a), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    The total area of floor space shall not exceed eight hundred fifty sq. ft. when there is only one bedroom, on a lot smaller than ten thousand sq. ft.
  4. Sec. 16-52.100(C)(2)(b)-(c), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    The total area of floor space shall not exceed one thousand sq. ft. when there is more than one bedroom.
  5. Sec. 16-52.100(C)(4), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    A front setback must yield to the extent necessary to enable the construction of an eight hundred square foot ADU with four-foot side- and rear-yard setbacks.
  6. Sec. 16-52.100(C)(5)(a), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    A detached ADU shall not exceed a height of sixteen feet, except:
  7. Sec. 16-52.100(C)(5)(b), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    Any attached ADU shall not exceed twenty-five feet. This clause shall not require a local agency to allow an ADU to exceed two stories.
  8. Sec. 16-52.100(C), Objective Development Standards Table, note 7, Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    One off-street parking space per accessory dwelling unit shall be required, unless parking exceptions as set forth in this section (16-52.100(C)(7)) apply.
  9. Sec. 16-52.100(D)(1), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    JADUs shall be no greater than five hundred square feet in size and contained entirely within a single-family residence.
  10. Sec. 16-52.100(D)(5), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    One of the dwelling units on the site (either the primary unit or the JADU) shall be owner-occupied.
  11. Sec. 16-52.100(C)(22), Municipal Code Ch. 16 (Zoning) Sec. 16-52 Permit Review and Decisions (16-52.100 Accessory Dwelling Unit; 16-52.110 Home Occupations; 16-52.080 Tidelands Permit; 16-52.020 Site Plan & Architectural Review), p. 1
    The ADU may be rented separate from the primary unit but may not be rented for a period of less than thirty consecutive days or used as a vacation rental.
This page summarizes Tiburon'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 Community Development - Building Division (permits, inspections, code enforcement), 1505 Tiburon Boulevard (415-435-7380 (Community Development main 415-435-7390)) before you build. Spot an error?