Multifamily and Duplex Properties for Sale in Monte Sereno: Zoning and Rent Rules

What multifamily in Monte Sereno looks like

Monte Sereno is almost entirely single-family homes on large lots, so income property here rarely means an apartment building. In practice it means a house with an ADU or JADU, an SB 9 two-unit project, a duplex or triplex in the small RM district, or attached homes on public-and-residential sites. The city’s code has added multifamily options over roughly the past decade, including the RM district and the P/RM overlay, both last amended in 2024. For two to four units, read financing 2-4 unit properties; for larger projects, see apartment building loans.

Where the zoning allows it

Chapter 10.05, amended most recently by Ordinance NS-242 in December 2024, sets these options:

RM in practice. RM allows up to three units by right, but the per-unit lot requirement of 14,520 square feet means a triplex needs a large parcel, roughly an acre of net area, unless slope rules require more.

SB 9. Monte Sereno’s two-unit rules in Section 10.05.080, adopted in 2021 and amended by Ordinance NS-240 in November 2023, use a city planner site development permit. They bar rooftop decks and require rentals longer than 30 days. Projects are not allowed on historic properties or certain rent-controlled ones. See our SB 9 lot split guide.

ADUs. ADUs and JADUs are permitted by right in every residential district and the P/RM overlay. See our ADU investment guide. Density bonuses are in Chapter 10.24.

Rent rules: state law only

The Attorney General’s rent cap page, updated July 16, 2026, lists only San Jose and Mountain View among Santa Clara County cities with local rent ordinances. Monte Sereno rentals therefore follow AB 1482: covered units may rise up to 8.6% for increases from August 1, 2026 through July 31, 2027, the All Other Counties figure that applies here. A single-family home or condo owned by an individual can be exempt if the required notice is given, and a duplex where the owner lives in one unit is also exempt. That covers much of Monte Sereno’s rental stock. Covered tenancies follow statewide just cause rules. The County’s unincorporated tenant rules do not apply inside the city. See our AB 1482 guide and just cause eviction guide.

Monte Sereno rental property rules

• No short-term SB 9 rentals. Units built under the two-unit rules must be rented for more than 30 days.
• Room rentals. Renting rooms to up to two people is permitted in each residential district.
• Licensing. Under Chapter 7.01, a lodging or apartment house with fewer than four sleeping rooms pays no license fee. The chapter does not otherwise address residential rentals, so ask the city whether a larger rental needs a license.
• Housing types. Residential care homes and supportive, employee and transitional housing are permitted in the residential districts.
• Transfer tax. The city’s Chapter 3.02 tax of $0.275 per $500 is administered by the County Recorder and appears to share the County’s $0.55 per $500 rate.

Hillsides, sewer and building limits

Most Monte Sereno lots use a slope-density minimum, so steep parcels need more land per unit than the base figure. Structural coverage ranges from 20% in R-1-44 to 40% in R-1-8 and RM. Height limits start at 14 feet for single-story portions, rising to 30 feet for two-story homes with added setbacks. Conservation Zone parcels need an average slope under 40% on the building site and a 32-foot setback from the 100-year flood influence line. Confirm sewer service and lateral condition before adding units; we did not verify which agency serves each area. Any building of three or more units with elevated balconies needs SB 721 balcony inspections, and older wood-frame structures may warrant a seismic retrofit review.

Underwriting a Monte Sereno multifamily purchase

1. Confirm the zoning; only RM allows a duplex or triplex outright.
2. Check net lot area against the 14,520-square-foot-per-unit RM rule and the slope-density minimum.
3. For SB 9, measure against the building area cap for the zone and model rentals over 30 days only.
4. Classify each unit under AB 1482, including owner-occupied duplex and single-family exemptions.
5. Collect leases and estoppel certificates.
6. Rebuild expenses with reassessed taxes in our rental property analysis.

Questions people ask

Sources & notes

1. Monte Sereno Chapter 10.05, Zoning District Regulations (GoCodebook)
2. Chapter 7.01, Business, Professions and Licensing
3. Chapter 3.02, Real Property Transfer Tax
4. California Attorney General, rent caps (updated July 16, 2026)

Note: We did not review the zoning map, the density bonus chapter, ADU standards or sewer service boundaries. AB 1482 exemption details are summarized from state law, not from a city source.

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

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