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

What multifamily in Fairfax looks like

Fairfax’s rental stock is small-scale. It is mostly duplexes and small apartment buildings on the flats near downtown, older cottages split into units, upstairs apartments over Bolinas Road and Broadway storefronts, and a growing number of ADUs on hillside lots. Large complexes are rare. The town is steep, so slope changes the lot size a building needs, and parking and access often decide what is buildable. For financing, see financing 2-4 unit properties and apartment building loans.

Where the zoning allows it

Fairfax’s zones are listed in § 17.012.010. Two or more units are allowed in these:

RM sites with three or more units need 300 square feet of open space per unit, at least 60 of it private. In WHO zones, rental projects need 15% low-income units at base density and 25% at top density, under a 55-year agreement.

ADUs and SB 9. RD lots may add up to two ADUs or one JADU under Chapter 17.048. See our ADU investment guide. The chapters we reviewed do not set separate SB 9 rules, and hillside, fire and access limits may affect a split. Check with planning and see our SB 9 lot split guide.

Rent rules: state law plus mandatory mediation

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

Measure I and just cause. Fairfax adopted local just cause and rent stabilization rules between 2019 and 2023. Ordinance 882, the last amendment, took effect October 6, 2023. In November 2024, Measure I, a citizen initiative, asked voters to replace those rules with state standards. Today’s Chapter 5.54 carries Ordinance 892, dated November 5, 2024. It lets landlords evict on any ground state law allows and bars the town from enforcing stricter limits. In practice, state just cause and relocation rules govern. See our just cause eviction guide. Confirm the current status with the town, since its older renter pages predate the change.

Mediation still applies. Chapter 5.55 requires mediation when increases exceed 5% in any 12 months, alone or combined. A tenant can request it within 10 days of the notice, and the increase generally waits until mediation ends. Landlords must give a notice of tenant rights at lease signing or renewal and with each increase notice. Without it, the increase is unenforceable. A landlord who does not take part in good faith cannot impose the increase. The chapter sets no rent cap of its own.

Fairfax rental property rules

• Income-based discrimination. Chapter 5.52 bars refusing an applicant only because part of the rent is paid by a subsidy such as a voucher.
• Short-term rentals. In the RD and commercial zones, a short-term rental is allowed only in an ADU or JADU built before January 1, 2020. Chapter 5.57 applies council program rules. Stays of 30 days or less owe the 10% hotel users tax.
• Transfer tax. Fairfax’s Chapter 3.16 sets $0.275 per $500. The county Recorder’s sheet lists $0.55 per $500 and names only San Rafael as adding a tax, so confirm the Fairfax charge with escrow.

Sewer laterals, hillsides and older buildings

The Ross Valley Sanitary District requires a Certificate of Compliance for the private sewer lateral when a property is bought or sold, when a remodel exceeds $75,000, and when a bathroom is added. Older laterals in the Ross Valley often fail testing, so get a video inspection and bid early in escrow. Hillside lots need more area and width as slope increases, and sites that miss the standard need a use permit or hill area residential development permit. Many Fairfax buildings are older wood-frame structures. Check for raised foundations, tuck-under parking and creekside setbacks, and consider a seismic retrofit review. Buildings of three or more units with elevated balconies or stairs need SB 721 inspections.

Underwriting a Fairfax multifamily purchase

1. Confirm the zone, slope and lot area, and test the legal unit count against RD or RM density.
2. Check whether the parcel is a housing opportunity site or in a WHO overlay before pricing redevelopment.
3. Classify each unit under AB 1482 and model increases at or below 8.8%, noting that anything over 5% triggers mediation.
4. Collect proof of tenant rights notices for every lease and increase, plus estoppel certificates.
5. Order the RVSD lateral inspection and certificate, and price any repair.
6. Rebuild expenses with reassessed taxes, both transfer taxes and actual utility costs in our rental property analysis.

Questions people ask

Sources & notes

1. Fairfax Municipal Code (GoCodebook, Oct. 2026): § 17.012.010, Ch. 17.084 RD, Ch. 17.088 RM, Ch. 17.126 WHO
2. Fairfax Title 5: Ch. 5.52, Ch. 5.54, Ch. 5.55, Ch. 5.57
3. Fairfax Title 3: Ch. 3.16, Ch. 3.32
4. Town of Fairfax, Ordinance 882
5. Marin County Elections, Measure I (Nov. 5, 2024)
6. California Attorney General, Rent Caps
7. Ross Valley Sanitary District, Compliance
8. Marin County Recorder, transfer tax

Note: The county measure page we read did not show the vote count. The status of Measure I is inferred from the current code text, so confirm it with the town.

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

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