Multifamily and Duplex Properties for Sale in South San Francisco: Zoning and Rent Rules

What multifamily in South San Francisco looks like

South San Francisco’s rental housing runs from duplexes and small walk-up buildings in the older neighborhoods around Grand Avenue and Linden Avenue to mid-century apartment complexes on the hillsides and newer high-density buildings near the Caltrain station and downtown. The current zoning, adopted in 2022, sets minimum densities in every multifamily district, so the city is actively steering larger projects toward transit. Every residential sale also carries an SFO noise disclosure. For two to four units, read financing 2-4 unit properties; for larger buildings, see apartment building loans.

Where the zoning allows it

Chapter 20.070, adopted by Ordinance 1646 in 2022 and amended June 12, 2024, sets the residential districts. Densities are in units per acre.

Minimum densities. In every RM and RH district, the minimum is the listed figure or the existing density, whichever is greater. A buyer can keep an existing building, but redevelopment must hit the minimum, so a plan to replace a fourplex with a few townhomes may not be approvable.

Downtown. The station area districts require 40 to 120 units an acre at minimum and allow up to 200 in ETC. Ground-floor residential space is limited to lobbies, gyms and similar spaces serving the building, and Grand Avenue sites must keep 75% of their frontage in active uses.

Housing on commercial land. State AB 2011 and SB 6 multifamily projects are listed as permitted in the city’s commercial, office and industrial districts, subject to state standards.

ADUs and SB 9. ADUs are listed in every residential district, with standards in Chapter 20.350. SB 9 units are permitted in RL-2.2 and RL-8. Density bonuses follow Chapter 20.390 and inclusionary rules Chapter 20.380. See our ADU investment guide and SB 9 lot split guide.

Rent rules: state law plus local relocation for displacement

Rent cap. The Attorney General’s rent cap page, updated July 16, 2026, places San Mateo County in the San Francisco Area, with covered units allowed up to 8.8% for increases from August 1, 2026 through July 31, 2027, and names East Palo Alto as the county’s only city with local rent stabilization. South San Francisco therefore has no local rent cap, and AB 1482’s cap and just-cause rules apply to covered units.

Tenant relocation. Chapter 8.70, as adopted by Ordinance 1682-2026 on April 22, 2026, covers tenants displaced because the owner must repair the unit to meet housing, building or safety codes, because the unit is uninhabitable, or because an agency orders them out.

• Notice. The landlord must give a city-approved notice within 24 hours of the event, with a copy to the city.
• Payments. Payments depend on the length of displacement: a per diem for short stays, a permanent relocation fee beyond 30 days, an immediate vacation fee when notice is under 30 days, and a counseling fee paid to the city. Amounts are set by Council resolution.
• Right to return. The tenancy continues, and the tenant can return on the same terms once the unit is habitable.
• Exclusions. Tenant-caused damage and outside disasters the landlord did not cause are among the exclusions.

The chapter has no lease-offer rule and no general just-cause rule beyond state law. See our AB 1482 guide and just cause eviction guide.

South San Francisco rental property rules

• Airport noise disclosure. Chapter 15.58 requires sellers of single-family and multifamily dwellings to disclose that SFO is within 3.75 miles of all homes in the city and that aircraft overflight noise applies, using the local option disclosure form.
• Conversions. Title 8 also has chapters on mobile home park conversions (8.80) and single room occupancy conversions (8.90); read them before changing the use of either kind of property.
• Transfer tax. The County’s documentary transfer tax is $0.55 per $500. The city’s Chapter 4.24 sets 27.5 cents per $500 under the state enabling law, which typically shares the County rate; confirm in escrow.

Noise insulation, older buildings and seismic

Inside the 65 CNEL noise footprint, homes built after January 1, 1993, and older homes reconstructed or renovated at 25% or more of market value, must meet FAA noise insulation standards. That can raise the cost of a deep apartment rehab. Under Chapter 8.70, a code-compliance repair that forces tenants out triggers relocation payments, so sequence work carefully. Older wood-frame buildings over garages merit a seismic retrofit review, and buildings of three or more units with elevated balconies need SB 721 balcony inspections, which can themselves lead to repairs that displace tenants.

Underwriting a South San Francisco multifamily purchase

1. Confirm the district and how the existing unit count compares with the minimum and maximum density.
2. Classify units under AB 1482 and model increases at or below 8.8% for covered units.
3. For any repair that could displace tenants, budget Chapter 8.70 per diem or relocation fees.
4. Check whether the building is inside the 65 CNEL footprint before planning a major renovation.
5. Collect leases, the rent roll and estoppel certificates.
6. Rebuild expenses with reassessed taxes, SB 721 and seismic costs in our rental property analysis.

Questions people ask

Sources & notes

1. South San Francisco Chapter 20.070, Residential Districts (GoCodebook)
2. Chapter 20.090, Downtown/Caltrain Station Area Districts
3. Chapter 20.100, Non-Residential Districts
4. Chapter 8.70, Residential Tenant Relocation
5. Chapter 15.58, Airport noise disclosure
6. Chapter 4.24, Real Property Transfer Tax
7. San Mateo County Clerk-Recorder, documentary transfer tax
8. California Attorney General, rent caps

Note: We did not review Chapter 20.350 (ADU standards), the inclusionary or density bonus chapters, the conversion chapters or the Council resolution setting relocation amounts. Neighborhood descriptions are general, not from a source.

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

Related: South San Francisco real estate guide · Commercial real estate in South San Francisco · Multifamily investing guide · Investor services