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

What multifamily in Woodside looks like

Woodside has almost no traditional apartment stock. Its income property is mostly estates and ranches with cottages, barns and second units, a growing number of ADUs and JADUs under the town’s generous rules for acre-plus lots, and caretaker or staff housing. The town has added multifamily districts in recent years, including zones tied to the Cañada College campus, so a few higher-density sites now exist on paper. For anyone buying in Woodside for rental income, the realistic question is usually how many legal units a large lot can carry, given septic, slope and fire access. For two to four units, see financing 2-4 unit properties; for larger projects, apartment building loans.

Where the zoning allows it

Section 153.100 of the zoning code sets these residential districts; the use tables were last amended by Ordinance 2025-646, effective March 27, 2025.

What this means for investors. Multifamily in Woodside is effectively tied to affordable housing: the MF district’s ministerial path requires lower-income units, and the Cañada College zones are on college land. A private buyer is unlikely to find an existing apartment building in these districts.

ADUs, JADUs and SB 9

Section 153.211, amended most recently by Ordinance 2025-647 in May 2025, is where most Woodside rental capacity comes from.

• Up to four units on large lots. On lots of an acre or more in R-1, SR, RR and SCP, a property can have up to four ADUs and JADUs combined, with no more than three ADUs; a fourth requires one unit to be a JADU. Lots under an acre get one ADU and one JADU.
• Size. Detached ADUs may reach 1,500 square feet including any attached garage, and attached ADUs the lesser of 1,500 square feet or half the house. JADUs are capped at 500 square feet.
• Barns. An ADU can occupy up to half a barn’s footprint, with a floor of 850 square feet, or 1,000 with more than one bedroom, and must be sprinklered and fire-separated.
• Setbacks. Only one new unit per lot may use the reduced four-foot side and rear setbacks.
• Owner occupancy. Required on any property with a JADU, not for standard ADUs.
• Septic. ADUs may have their own septic system or share one with the house or other ADUs, under the town’s wastewater code.

SB 9. Woodside has SB 9 unit development standards in Section 153.980 and an SB 9 lot split article in Chapter 152. See our SB 9 lot split guide and ADU investment guide.

Rent rules: state law only

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. Woodside has no local rent ordinance in its code outline, so AB 1482’s cap and just-cause rules apply to covered units. A single-family home or ADU owned by an individual can be exempt with proper notice, while units owned through a corporation or REIT generally are not. See our AB 1482 guide and just cause eviction guide.

Woodside rental property rules

• No short-term ADU rentals. A rented ADU must be leased for at least 30 consecutive days.
• Caretaker and staff housing. Check whether any existing cottage or barn apartment was permitted as an ADU; an unpermitted unit may need legalizing before they can be rented.
• Animals. If tenants keep horses, the lot must meet the town’s one-acre minimum and one-horse-per-half-acre rule.
• Transfer tax. The County’s documentary transfer tax is $0.55 per $500. Woodside’s transfer tax article sets 27.5 cents per $500 under the state enabling law, which typically shares the County rate; confirm in escrow.

Septic, slopes and fire access

Most added units in Woodside depend on the septic system. Under the town’s private wastewater rules, a septic system is allowed only where public sewer is unavailable. It needs a town permit after a site inspection and percolation tests and must meet the County Health Officer’s regulations, and the town will not issue a permit where soils or area are inadequate. On slopes of 35% to 50%, ADU septic systems must follow County standards. The fire district may require driveway upgrades in some slope cases. Older outbuildings converted to living space may need a seismic retrofit review, and any building of three or more units with elevated balconies needs SB 721 balcony inspections.

Underwriting a Woodside multifamily purchase

1. Confirm the permitted status of every unit; older estates can include unpermitted cottages or barn apartments.
2. Count how many more ADUs and JADUs the lot can legally add under Section 153.211.
3. Have the septic system evaluated for the total number of bedrooms you plan to rent.
4. Classify units under AB 1482 and model increases at or below 8.8% for covered units.
5. Collect leases and estoppel certificates for every occupied unit.
6. Rebuild expenses with reassessed taxes, septic, well or water, and insurance costs in our rental property analysis.

Questions people ask

Sources & notes

1. Woodside Section 153.100, Zoning Districts and Uses (GoCodebook)
2. Woodside Section 153.211, Accessory Dwelling Units
3. Woodside Municipal Code index (SB 9 sections)
4. Chapter 51, Article III, Private Wastewater Disposal
5. Chapter 35, Article III, Real Property Transfer Taxes
6. San Mateo County Clerk-Recorder, documentary transfer tax
7. California Attorney General, rent caps

Note: We did not read Section 153.980 or the SB 9 lot split article, the zoning map showing where MF and MF-20 apply, or the housing element. Notes about unpermitted estate units are general cautions, not from a source.

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

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