SB 9 In West Portal: What’s Feasible On SFR Lots

If you own or are eyeing a single-family lot in West Portal, SB 9 might let you create a second home, split your lot, or both. But what is feasible on a typical parcel here depends on much more than the law on paper. West Portal’s lot sizes, slopes, access, and design context all matter. This guide breaks down what SB 9 allows, how San Francisco applies it, and how to evaluate your property step by step before you invest time and money.

Why SB 9 Feasibility Matters

West Portal is beloved for its village feel, strong schools, and classic homes. Many lots sit near the Muni station and along quiet blocks. SB 9 can be a path to add gentle density while keeping the neighborhood’s character, but feasibility is parcel by parcel. On some lots a second unit fits well. On others, only a light touch makes sense. The right plan balances design, privacy, access, and cost.

SB 9 Options on SFR Lots

Two Primary Pathways

State law allows two ministerial paths on single-family parcels, subject to objective standards:

• Two-unit development on one lot. You can create a duplex or two primary units on your existing parcel if you meet state rules and San Francisco’s objective design standards. The city processes these ministerially when the project is eligible under SB 9 and local guidance.
• Urban lot split. You can divide one single-family lot into two legal parcels, with each new parcel generally at least 1,200 square feet and one parcel allowed to be as small as 40 percent of the original per state code. Each resulting parcel can then host up to two units, if it meets all standards. The state does not require a city to allow more than two units on a resulting parcel.

San Francisco implements SB 9 through a ministerial process, applying citywide objective standards for height, setbacks, privacy, light, and open space. See the Planning Department’s SB 9 page and Objective Design Standards for specifics on local submittals, screening, and uniform design checks (SF Planning SB 9; Objective Design Standards).

SB 9 vs. ADUs

ADUs add accessory dwellings that remain subordinate to the main home, often with simpler construction and smaller footprints. SB 9 creates two primary dwellings or two buildable parcels. If your goal is rental income with minimal site work, one or two ADUs may be simpler. If your goal is a true second home, a future condo map, or a lot split for legacy planning, SB 9 may be the better fit. In practice, West Portal owners often explore both, then choose the path that fits geometry, access, privacy, and budget.

Design, Scale, and Privacy

San Francisco applies objective rules to window placement, private open space, and massing for SB 9 projects. These aim to protect light, air, and neighbor privacy while allowing two homes. In West Portal, entries, landscaping, and step-backs can help new homes feel consistent with the streetscape while giving each unit its own identity. The city reviews these elements against adopted checklists, not subjective taste (Objective Design Standards).

Owner-Occupancy and Tenants

For urban lot splits, the applicant must sign an affidavit to live in one of the homes as a principal residence for at least three years after approval per state law. In addition, parcels with tenant occupancy in the last three years are excluded from certain SB 9 actions. These protections are decisive for many SFRs and should be verified early (statutory exclusions).

Evaluate Your Property for SB 9

Lot Size, Shape, Slope

Start with geometry. Can you form two code-compliant building areas if you add a unit or split the lot? Narrow, shallow, or sloped parcels can constrain layouts, access, and excavation cost. The state minimum for a resulting parcel is generally 1,200 square feet, but fitting a real dwelling also requires setbacks, utilities, and private open space. San Francisco’s Planning Code and objective standards will govern where and how you can build (Planning Code reference).

Existing Home and Setbacks

The current building footprint, yard sizes, and window placement drive what is possible. Many West Portal homes sit toward the front with usable rear yards. That can favor a rear-lot or rear-wing second unit with separate entry. If an older garage occupies the rear corner, a replacement structure may pair parking with a new unit above, if access and fire rules allow. New units must meet setback and privacy rules in the city’s objective standards.

Access, Parking, and Fire

State law lets cities require up to one off-street space per unit, but not within one half-mile of a major transit stop or high-quality transit corridor. The West Portal Muni station qualifies as a major stop, which means many parcels in walking distance will not be required to add parking for SB 9 units. Always confirm your specific distance and site conditions. Fire access, sprinklers, and path-of-travel rules will also shape plans and may affect whether a driveway or widened side yard is needed (SB 9 parking rule; SFMTA West Portal station context).

Overlays and Context

Historic status, landmark districts, and other overlays can make SB 9 ineligible. Parcels in a historic district or landmark area are excluded from SB 9’s ministerial processing per statute. San Francisco screens SB 9 projects using objective eligibility criteria and applies uniform design standards citywide (SF Planning SB 9; Director’s Bulletin).

Feasible Build-Out Scenarios

Keep House, Add Unit

For many lots, the simplest move is to keep the main home and add a second primary unit as a connected wing or a detached structure. Focus on:

• Separate entry, clear address, and private outdoor space
• Stacked plumbing walls and efficient mechanical runs
• Window placement that protects neighbor privacy using offsets and screens
• Sound separation and light wells for good daylight per objective rules

This path avoids survey and map costs of a split while still creating a second primary dwelling under SB 9.

Rebuild as Two Units

If the existing structure is functionally obsolete or poorly located, a full rebuild to create two homes can be viable. You will need to meet San Francisco’s objective design standards and fire, structural, and energy codes. This route can yield the cleanest layouts and shared systems, but it demands careful phasing if you plan to stay onsite during construction and must respect any demolition limits.

Urban Lot Split Path

With adequate width, depth, and services, an urban lot split can produce two legal parcels, each generally no smaller than 1,200 square feet. After the split, each parcel can host up to two units, though the city is not required to allow more than two units per resulting parcel per state code. Key issues:

• Survey, parcel map, and Public Works processing
• Utility separations, new meters, and easements
• Driveway, frontage, and fire access to the rear parcel
• Owner-occupancy affidavit for three years after approval

In West Portal’s built-out fabric, a split often works best on wider or deeper lots with alley access or clear side-yard corridors.

When Not a Fit

SB 9 is likely not a match if your lot sits in a historic district, housed tenants in the last three years, or cannot satisfy fire access, slope stability, or utility requirements. In those cases, explore ADUs, interior reconfiguration, or a design-led addition instead. Early screening can save months.

Permits, Costs, and Timelines

Early Feasibility Steps

• Pull zoning, overlays, and historic status on the city’s Property Information Map (PIM), and confirm your RH-1 zoning type (PIM help).
• Confirm SB 9 eligibility and submittal requirements with the Planning Department’s SB 9 resources and Director’s Bulletin (SF Planning SB 9; Director’s Bulletin).
• Do a site walk with a designer to test massing, entries, and services. Sketch simple stack diagrams to study plumbing and structure.

Survey and Map Work

For a lot split, you will need a boundary and topographic survey and a parcel map application through Public Works. Even for a two-unit build without a split, a topo survey helps with grading, drainage, and height checks. Identify any recorded easements that might affect new footprints.

Permitting and Reviews

San Francisco processes eligible SB 9 projects ministerially and aims to issue a decision within 60 days of a complete application. Under SB 450, failure to act within that period can be deemed approval, and cities cannot apply non-uniform standards that disadvantage SB 9 projects relative to the base zone (SB 450 update). Expect coordinated reviews with Planning, Building Inspection, Fire, Public Works, and utilities. The city applies its SB 9 Objective Design Standards as uniform checklists (Objective Design Standards).

Construction Sequencing

• Keep-and-add projects can phase work to allow partial occupancy during early stages, then switch over utilities before finishes.
• Full rebuilds are fastest on a clean site but require longer temporary housing and more intensive coordination with neighbors.
• Utility upgrades, separate meters, and trenching can drive both schedule and cost; coordinate early with SFPUC and PG&E as the city recommends (SF Planning SB 9).

Budgeting and Financing

Plan for soft costs (surveys, design, engineering, city fees, utility fees, legal and title work for splits) and hard costs (site work, structure, MEP systems, finishes). Add a healthy contingency for hillside excavation, utility conflicts, and fire/life-safety upgrades. In today’s market, financing often blends cash, construction loans, and potential partner equity. Keep pro formas conservative. Citywide, early SB 9 uptake has been modest, which underscores the role of costs and site constraints in real outcomes (SF Chronicle reporting).

Value, Returns, and Strategy

Sell vs. Hold

• Entitle then sell: Securing ministerial approvals or a recorded parcel map can lift value without taking on construction risk.
• Build then sell: Two brand-new homes in West Portal can command strong buyer interest if design and privacy are excellent. Carry costs and sales timing matter.
• Build and hold: Live in one, rent the other. This can work well for long-term planners who value stability and tax advantages.

Buyer and Renter Demand

Design and function drive demand. Private entries, acoustic separation, daylight, and outdoor space are top priorities. Families like three-bed floor plans with storage; professionals value flexible dens and EV-ready parking if provided. Even near transit, consider bike storage and a small workshop area.

Primary Home With Income

For many owners, the best outcome is a refined primary home plus a second unit that supports multigenerational living or stable rental income. SB 9’s two-unit path can deliver that balance without the complexity of a lot split, especially near the West Portal Muni stop where parking requirements may be waived if within the half-mile radius (state parking rule).

Alternate Paths to Density

If SB 9 is not a fit, look at one or two ADUs, interior reconfiguration to add bedrooms and baths, or a detached studio for work and guests. These often come with lower budgets and shorter timelines while still adding utility and value.

Next Steps With Local Experts

SB 9 success in West Portal starts with clean facts, a thoughtful concept, and a measured strategy. Gather your parcel data, test a couple of massing options, and confirm ministerial eligibility before you hire full plans. For local process clarity, study San Francisco’s SB 9 resources and objective standards, and expect a 60-day ministerial decision after your application is complete (SF Planning SB 9; Objective Design Standards; state code; SB 450 update).

Call to Action

Curious what’s feasible on your West Portal lot? Request a free property review and pricing conversation tailored to your goals. Start with a quick valuation and SB 9 screen, then we can map out next steps and timing that fit your life. Request your plan with Mandy Lee.

FAQs

What is the maximum number of homes I can create under SB 9?

• On one original single-family lot, the theoretical maximum is four homes by splitting the lot into two parcels and building up to two units per parcel. The state does not require more than two units on any resulting parcel per statute.

Do I need to add parking for SB 9 units in West Portal?

• Often no. If your lot is within a half-mile of the West Portal Muni station or another major transit stop, the city cannot require off-street parking for SB 9 units. Confirm your exact distance and site context (state parking rule; West Portal station context).

How fast is the SB 9 approval?

• San Francisco targets a ministerial decision within 60 days of a complete application. SB 450 strengthens this timeline and limits non-uniform local standards that would disadvantage SB 9 projects (SB 450 summary; SF Planning SB 9).

What would make my property ineligible?

• Common blockers include tenant occupancy in the last three years, location in a historic district or landmark parcel, a prior SB 9 split, or adjacent sequential splits by the same owner. These are spelled out in state law and applied in San Francisco’s screening (eligibility limits; SF Planning guidance).

How do I check my zoning and historic status?

• Use the city’s Property Information Map to confirm zoning and any historic badges. Then review San Francisco’s SB 9 Objective Design Standards to understand height, setback, and privacy rules (PIM help; Objective Design Standards).

Is a lot split better than adding a second unit on one lot?

• It depends on your goals. A split can unlock two sellable parcels but adds survey, mapping, utilities, and an owner-occupancy affidavit for three years. A two-unit build on one lot is simpler and can still deliver strong value. Test both on paper before you decide (state split rules).

Are SB 9 projects common in San Francisco?

• Not yet. Early reporting shows limited SB 9 construction applications citywide, reflecting costs, site limits, and design constraints. Feasibility is case-by-case, especially in established neighborhoods like West Portal (SF Chronicle report).

Can I combine SB 9 with ADUs?

• Sometimes, but stacking programs can be complex. Start with a clean SB 9 concept that meets objective standards. If you later layer an ADU, confirm how setbacks, open space, and utilities interact under city code and ministerial rules (SF Planning SB 9).