Marin County · Land use · Duplex
Where is a duplex allowed in Marin County?
In Marin County, a duplex is allowed in 10 base zones (R2, RMP, VCR, RMPC, C1 and 5 more, 5 with a condition), needs an use permit (conditional use permit or master use permit) in 2 (RCR and OA, 1 with a condition) and not allowed in 3 (Marin County use tables, read October 2026).
Key points
- Allowed: R2, RMP, VCR, RMPC, C1, CP, AP, OP and 2 more
- Needs a permit: RCR and OA
- Not allowed: RX, RF and IP
Find your lot's zone on the city zoning map, then read its row. Every status below was read from the Marin County Municipal Code use tables (read October 2026). Base zones only. General information, not legal advice — check with the city before you apply.
Zones where a duplex can go
Marin County's code calls this use “Two-family dwellings”. Each row links to the use table it comes from. A zone marked “see note” has a condition in the code, for example upper floors only or a larger lot.
| Zone | Status | Code |
|---|---|---|
| R2 Residential Two-Family | Allowed | § 22.10.030 |
| RMP Residential Multiple Planned | Allowed | § 22.10.030 |
| VCR Village Commercial Residential | Allowed | § 22.12.030 |
| RMPC Residential Commercial Multiple Planned | Allowed | § 22.12.030 |
| C1 Retail Business | Allowed — see note Note 3: Dwellings allowed above the first floor only. First floor shall be reserved for non-residential use. Note 4: Dwellings, except for affordable housing, shall be accessory to the primary commercial use. See 22.32.150 (Residential Uses in Commercial/Mixed Use Areas). | § 22.12.030 |
| CP Planned Commercial | Allowed — see note Note 4: Dwellings, except for affordable housing, shall be accessory to the primary commercial use. See 22.32.150 (Residential Uses in Commercial/Mixed Use Areas). | § 22.12.030 |
| AP Admin and Professional | Allowed — see note Note 4: Dwellings, except for affordable housing, shall be accessory to the primary commercial use. See 22.32.150 (Residential Uses in Commercial/Mixed Use Areas). | § 22.12.030 |
| OP Planned Office | Allowed | § 22.12.030 |
| H1 Limited Roadside Business | Allowed — see note Note 4: Dwellings, except for affordable housing, shall be accessory to the primary commercial use. See 22.32.150 (Residential Uses in Commercial/Mixed Use Areas). | § 22.12.030 |
| PF Public Facilities | Allowed — see note Note 4: Housing is permitted in combined districts that allow housing, such as PF-RSP, PF-RMP, and PF-ARP. Single-family, two-family, and multi-family dwellings are principally permitted only on the Countywide Plan's Housing Overlay Designation sites. | § 22.14.030 |
| RCR Resort and Commercial Recreation | Needs an use permit (conditional use permit or master use permit) | § 22.12.030 |
| OA Open Area | Needs an use permit (conditional use permit or master use permit) — see note Note 3: Only dwellings for teachers or custodial staff, or dwellings clearly accessory to the primary use of the site for agricultural purposes are allowed. | § 22.14.030 |
Zones where it is not allowed
What else applies
- State law: SB 9 (Gov. Code § 65852.21) allows two homes on most single-family lots with a ministerial permit, also where this table says no.
- Not covered here: Coastal zoning districts (Title 20, Tables 5-1, 5-2, 5-3, Coastal Agricultural, Residential and Commercial districts): only the intro section 20.62.040 is in the packet, the tables are missing.; Section 22.32 standards (22.32.030 animal keeping, 22.32.050 child care, 22.32.085 SRO, 22.32.095 homeless shelters, 22.32.150) and Article VIII definitions are not in the packet.; Combining districts (e.g. PF-RSP, San Geronimo Valley) can change allowed uses.. Overlay zones and specific plans can also change the answer.
Other uses in Marin County
Who this affects
Frequently asked questions
Can I have a duplex in the RCR zone in Marin County?
Only with an use permit (conditional use permit or master use permit). Marin County's use table lists it that way in RCR (Resort and Commercial Recreation) (§ 22.12.030).
Can I have a duplex in the RX zone in Marin County?
No. Marin County's use table does not allow it in RX (Residential Mobile Home Park) (§ 22.10.030).
Can I have a duplex in the R2 zone in Marin County?
Yes. Marin County's use table lists it as allowed in R2 (Residential Two-Family) (§ 22.10.030).
General information, not legal advice.
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