Multifamily and Duplex Properties for Sale in Woodacre: Zoning and Rent Rules

What multifamily in Woodacre looks like

Woodacre is a single-family village on a 1913 subdivision, but it has some rental density. The San Geronimo Valley Community Plan (p. IV-4) notes that some apartment buildings and other multifamily units exist in Woodacre, Forest Knolls and Lagunitas. It also says many valley homes have second units in converted garages, basements or cottages, some built without permits. Typical income property is a house with an ADU, a small older multi-unit lot in the Flats, or units in a village building. For financing, see financing 2-4 unit properties and apartment building loans.

Where the zoning allows it

Woodacre is unincorporated and inland, so Marin County’s Title 22 applies and no coastal permit is needed. The community plan maps its commercial categories to county districts. Chapter 22.12 sets the housing densities:

Confirm the district on the county zoning map. Many older multi-unit Woodacre lots are likely legal nonconforming and may not be rebuildable at their current unit count. The plan’s valley-wide buildout figures (1,566 homes in 1995, 2,369 in theory) exclude second units and were described as maximums that septic and slope would reduce.

ADUs. ADUs are the main way to add units. In Woodacre a legal ADU almost always needs a septic design approved by county Environmental Health, and the plan says a leach field generally needs about an acre. See our ADU investment guide.

SB 9. SB 9 requires adequate services, and many Woodacre Flats lots cannot support two primary units on septic. Hazard and creek constraints can also bar it. Confirm with the county and see our SB 9 lot split guide.

Rent rules: state law plus Marin County’s just cause and mediation

Rent caps. The Attorney General’s rent cap page puts Marin in the San Francisco Area region. Covered units can rise by at most 6.3% from August 1, 2025, and 8.8% from August 1, 2026 through July 31, 2027. No local cap applies. See our AB 1482 guide.

County just cause. Woodacre is unincorporated, so Marin’s just cause ordinance applies. It is Ordinance 3705, Chapter 5.100, adopted December 18, 2018. It covers lots with three or more dwelling units. Unpermitted units are not exempt, so a Woodacre house with two unpermitted cottages behind it is likely covered. Permitted ADUs and JADUs do not count toward the threshold. See our just cause eviction guide.

Mediation. Under the county’s mandatory mediation program, tenants can require mediation of increases over 5% in 12 months. A landlord who does not take part in good faith risks having the increase deemed invalid.

Woodacre rental property rules

• Short-term rentals. The county’s Chapter 5.41 caps Woodacre at 12 licenses initially and 8 over time. One license is allowed per owner and one rental per property. Multifamily units and ADUs created or legalized after 2020 or 2021 are ineligible. Underwrite second units as long-term rentals.
• Business license. Rentals in unincorporated Marin need a county business license, billed per unit and renewed by July 31.
• Transfer tax. Only the county’s $0.55 per $500 applies, per the Recorder’s sheet.

Septic, the wastewater study and older buildings

The county’s wastewater Q&A is essential reading for a Woodacre investor. It reports failing septic systems in the Flats, caused by poor soils, high groundwater, small lots and age. Fewer than half of developed properties have county septic records, and about two-thirds of Woodacre systems inspected in 2004–2005 were marginal or unacceptable.

A community system has been studied since 2011. The 2017 EIR notice proposed piping Woodacre wastewater to a plant at the San Geronimo Golf Course. The county project page says that effort paused when the course closed in 2017. Current study is revisiting a Fire Road leachfield for up to about 200 existing homes, with voluntary connection. The Q&A notes that the Marshall community’s similar project came with a deed restriction limiting future additions to 500 square feet. It does not say whether Woodacre would follow suit. Do not underwrite added units on the hope of sewer.

Older wood-frame buildings on the Flats and canyon slopes may warrant a seismic retrofit review, and buildings of three or more units with elevated decks need SB 721 inspections. Canyon parcels carry wildfire exposure and defensible-space work.

Underwriting a Woodacre multifamily purchase

1. Request the county septic file and order a full inspection. Many Woodacre properties have no file at all.
2. Confirm the zoning, the permit status of each unit and any nonconforming rights.
3. Apply the county just cause test (three or more units, counting unpermitted ones) and classify each unit under AB 1482.
4. Model increases at or below 8.8%, and plan for mediation above 5%.
5. Collect leases, the rent roll and estoppel certificates.
6. Rebuild expenses with reassessed taxes, septic repair reserves and fire insurance in our rental property analysis.

Questions people ask

Sources & notes

1. Marin County Code Ch. 22.12 (GoCodebook)
2. San Geronimo Valley Community Plan (1997) (community-hosted copy)
3. Marin County Environmental Health, wastewater Q&A
4. Marin County, San Geronimo/Woodacre community wastewater page and CEQAnet SCH 2017032067
5. Marin County, Just Cause Eviction and Mandatory Mediation
6. California Attorney General, Rent Caps
7. Marin County Code Ch. 5.41, Short Term Rentals
8. Marin County Business License and Recorder transfer tax

Note: We could not read the plan’s Woodacre village section in full or the zoning map, so confirm parcel zoning with the county.

General information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

Related: Woodacre real estate guide · Commercial real estate in Woodacre · Multifamily investing guide · Investor services