Zoning, building permits and septic rules in the Town of Tiburon, California

At a glance

Building permit

Required for nearly all construction; issued by the Town of Tiburon Building Division²

Zoning

Yes, the Town sets its own residential and other zones under the Tiburon Code¹⁵

Septic

Marin County Environmental Health Services handles septic permits countywide; confirm your address with them³

RV living

Prohibited for dwelling purposes on any property in town⁴

Accessory dwelling units

Allowed in single- and multi-family zoned lots; junior ADUs in single-family lots⁶

Minimum lot size

Set by zone: 10,000 sq ft in R-1, 20,000 in RO-2, 40,000 in RO-1, larger on steep slopes⁷

Building code

2022 California Residential Code with Town amendments⁸

Wells

California delegates well permits to local agencies; we could not confirm who issues them inside Tiburon⁹

Who to call

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

Does Tiburon, California have zoning, and what does it mean for lot size and RVs?

Yes. The Town of Tiburon adopts and administers its own zoning, and its Planning Division manages development under the Zoning Ordinance and the Municipal Code¹¹⁰. Marin County's own zoning code covers only unincorporated land, not incorporated towns¹¹.

Residential zones in Tiburon include R-1, R-1-B-A, R-1-B-2, RO-1, RO-2, R-2, R-3, R-3-10, R-4, RPD and RMP⁵. Lot standards depend on the district: R-1 lots need at least 10,000 square feet, RO-2 at least 20,000 and RO-1 at least 40,000, and steep sites can require larger lots⁷. Maximum lot coverage is 15% in RO-1 and RO-2 and 35% in R-2¹².

An RV cannot serve as a home: the Tiburon Code makes it unlawful to place, keep or maintain a travel trailer, recreational vehicle, camper or similar vehicle for dwelling purposes on any property in town⁴.

Do you need a building permit in Tiburon, and who issues it?

The Town of Tiburon Building Division issues building permits inside town limits, performs plan review and conducts inspections². Tiburon states that building permits are required, with few exceptions, for all construction involving electrical, mechanical, plumbing, re-roofing or drainage work, for all fences or walls, and for window replacements, kitchen or bath remodels and storage sheds².

Tiburon adopted the 2022 California Residential Code, with Town amendments, for residential construction⁸. A permit stays valid for 18 months and can be extended six more months at no cost².

Marin County's building permit rules, including its exemption list, apply to unincorporated Marin County only, so they do not set the rules for a Tiburon lot¹³. California's owner-builder exemption concerns contractor licensing, not whether a permit is needed¹⁴. We could not confirm Tiburon's own owner-builder or certificate-of-occupancy procedures; ask the Building Division at 415-435-7380².

How do septic permits work inside Tiburon?

Septic permits are not a Town of Tiburon function that we could confirm. Marin County Environmental Health Services processes permits for new and replacement septic systems, and the county's septic rules are written countywide³¹⁵. A septic construction permit is required before building a system, and the system may not be covered until the Health Officer inspects it¹⁵¹⁶.

We could not confirm whether a particular Tiburon address is on a public sewer or on a septic system, so ask Environmental Health Services before you plan either one¹⁷. Where a public sewer main is within 400 feet and connection is possible, the county's rules bar expanding an existing septic system and require sewer connection instead¹⁸.

For Marin County overall, USDA rates only about 2% of soils as not limited for a conventional drain field, so expect a site evaluation and possibly an engineered system¹⁹.

Can you live in an RV, tiny home or accessory dwelling in Tiburon?

RVs: no. Living in a travel trailer, camper or recreational vehicle for dwelling purposes is unlawful on any property inside Tiburon⁴. The temporary RV and emergency-shelter provisions in Marin County's shelter-crisis declaration cover unincorporated Marin only, so they do not reach Tiburon²⁰.

Tiny homes: we could not confirm a Tiburon rule. California treats a tiny home as a legal dwelling only when it qualifies as a manufactured home, a code-compliant house, an RV or another recognized type, and a unit that fits none of those is illegal to occupy²¹. Ask the Planning Division at 415-435-7390 before buying one¹⁰.

Accessory dwelling units: Tiburon allows ADUs on single-family and multi-family zoned lots and junior ADUs on single-family lots, reviewed ministerially through a building permit⁶. A junior ADU can be up to 500 square feet inside the existing single-family structure, and the Town's review deadline is 60 days unless the applicant asks for a delay⁶.

Building a home in Tiburon: the steps, in order

1. Confirm the zone and lot standards with the Planning Division, including any slope-based lot-size rule and the lot coverage limit for your district¹⁰⁷¹².
2. Check flood exposure: development in a special flood hazard area is regulated under Tiburon's chapter 13D²².
3. Find out whether the lot is on sewer or needs a septic system, and if septic, apply to Marin County Environmental Health Services¹⁷¹⁵.
4. Submit the building permit application to the Building Division at building@townoftiburon.gov, then respond to plan check comments².
5. Build under the adopted 2022 California Residential Code and schedule inspections with the Building Division⁸².
6. If the work involves subdividing land, expect Tiburon's subdivision rules in chapter 14 of the Municipal Code to apply²³.

What stays with Marin County, and what should you check before buying in Tiburon?

Septic permits and the county's septic rules sit with Marin County Environmental Health Services³. California leaves well permits to local enforcing agencies, such as county environmental health departments, and we could not confirm who issues well permits inside Tiburon, so ask Environmental Health Services at 415-473-6907⁹¹⁷. For land outside Tiburon's limits, see the Marin County page.

Marin County figures give context for cost: the typical home value is about $1.5 million²⁴ and the effective property tax rate is about 0.7%²⁵. These are county-level numbers, not Tiburon-only.

Before you buy, confirm the zone and slope rules with the Planning Division, the flood status of the lot, and whether sewer or septic serves it.

Watch-outs

• Do not assume Marin County's rules apply to a Tiburon lot: the county's building permit, zoning and RV rules cover unincorporated land only¹¹.
• Septic and well rules for a specific Tiburon address are unconfirmed on our side, so call Marin County Environmental Health Services at 415-473-6907 before you rely on either¹⁷.
• Lot size, lot coverage and slope rules differ by zone and by parcel, so confirm your district with the Town of Tiburon Planning Division at 415-435-7390⁷¹⁰.
• Flood zones carry their own rules, including limits on how long an RV can sit on site and elevation rules for manufactured homes in zones A and V²².

Sources

1. Tiburon Code 16-100.020 Definitions (Town of Tiburon), quoted and re-checked
2. Town of Tiburon Community Development - Building Division (townoftiburon.org)
3. Septic systems/onsite wastewater treatment systems, quoted and re-checked
4. Tiburon Code 16-32.030 General parking regulations (Town of Tiburon), quoted and re-checked
5. Tiburon Code 16-21.020 Purposes of the residential zones (Town of Tiburon), quoted and re-checked
6. Tiburon Code 16-52.100 Accessory dwelling unit (Town of Tiburon), quoted and re-checked
7. Tiburon Code 16-21.040 Residential zones development standards (Town of Tiburon), quoted and re-checked
8. Tiburon Code 13-4.2 Residential Code (Town of Tiburon), quoted and re-checked
9. Well Standards (California statewide rule), quoted and re-checked
10. Town of Tiburon Community Development - Planning Division (townoftiburon.org)
11. Title 22 - Development Code, quoted and re-checked
12. Tiburon Code 16-21.040 Residential zones development standards (Town of Tiburon), quoted and re-checked
13. Do I need a building permit?, quoted and re-checked
14. Owner-Builder Overview, quoted and re-checked
15. Septic systems/onsite wastewater treatment systems, quoted and re-checked
16. Septic systems/onsite wastewater treatment systems, quoted and re-checked
17. Marin County Community Development Agency - Environmental Health Services (marincounty.gov)
18. Regulations for Design, Construction and Installation of Individual Sewage Disposal Systems, quoted and re-checked
19. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
20. County Declares Shelter Crisis to Provide Temporary Emergency Housing, quoted and re-checked
21. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
22. Tiburon Code 13D-13 Anchoring (Town of Tiburon), quoted and re-checked
23. Tiburon Code 16-21.040 Residential zones development standards (Town of Tiburon), quoted and re-checked
24. Typical home value (Zillow): Bolthole Index county data
25. Effective property tax rate: Bolthole Index county data

Written October 16, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.