Better Design Strategies for New Housing in San Francisco

San Francisco’s housing story is at a crossroads. The 2024 Housing Inventory Report shows that only a small share of new units are rising in mid-rise, 5–19 unit buildings.

There is a long-standing desire for more affordable, neighborhood-friendly options. This post examines the idea of Parisian-style six-story “gentle density.”

It also looks at the constraints of current fire codes that require two exits for most multiunit buildings above three stories. A single-stair approach might unlock lighter, brighter, and more flexible housing on narrow lots.

Design competition examples and pending state policy could reshape how we build multifamily housing in dense urban settings.

SF’s Housing Landscape: Density, Light, and Street Activation

New growth on the West Coast has mostly focused on single-family replacement or larger, high-rise projects. This leaves modest mid-rise options scarce.

The city’s narrow lots and traditional streets benefit from buildings that engage the ground level and invite pedestrian life. Maximizing daylight in every unit is also important.

In 2024, only 163 of 1,735 total new homes came from 5–19 unit buildings. This shows a gap between policy goals and what is actually being built.

Gentle density refers to six-story, Parisian-inspired buildings that feel human-scale at street level. This approach can activate storefronts, improve daylight in corridors, and expand housing supply while preserving neighborhood character.

Single-Stair Design: Opportunity vs. Regulation

Current U.S. and California fire codes usually require two exit stairwells for most multiunit structures above three stories. For developers on narrow San Francisco lots, this rule can lead to long corridors and less natural light.

Refining the fire safety framework for single-stair configurations—along with modern mitigation strategies—could provide more design flexibility and cost savings.

A single-stair approach can improve unit variety and allow for better light and ventilation. It can also reduce construction costs.

Proponents estimate savings of 6%–13% in overall project costs. International best practices and modern fire safety measures inform this conversation.

Design Competition Demonstrates Feasible Concepts

The National Single Stair Architectural Design Competition showcased concepts for narrow-lot sites that fit neighborhood scale and street life. Two standouts show how a single stair can support thoughtful massing and community-friendly ground-floor uses.

• First Place — Steplight by David Baker Architects: a ten-unit, six-story building with tiered massing, light wells, and a modest ground-floor cafe. The design emphasizes daylight, pocketed open spaces, and a varied unit mix.
• Second Place — Let Me Live in Your City by Siddell Pakravan Architects: a nine-unit design focusing on light, air, and street connection with one- to three-bedroom units for families and flexible living.

Policy Momentum: AB 2252 and Fire Marshal Perspectives

California Assembly Bill 2252 would direct the Department of Housing and Community Development to propose standards for single-stair multiunit buildings up to six stories. The legislation shows state-level interest in expanding design options for dense urban areas.

The Cal Fire Office of the State Fire Marshal has raised safety concerns about this approach. This highlights the challenge of balancing fire protection with innovative building designs on narrow sites.

The debate centers on setting clear safety criteria and standardized design approaches. Performance-based codes could help achieve safety without limiting new housing options.

Implications for Practice: What This Means for Builders, Communities, and Neighbors

For practitioners, embracing single-stair multiunit designs could unlock a broader spectrum of housing types on limited parcels. These designs offer improved daylight, better ventilation, and potential cost efficiencies.

For neighborhoods, well-executed designs that front streets with active uses and well-lit ground floors can sustain lively, walkable blocks.

For policymakers, balancing safety with flexibility will require clear guidelines and robust risk assessments. Pilot programs can help test performance in real-world conditions.

• Prioritize ground-floor activation and street connectivity to maintain neighborhood vitality.
• Develop design standards that ensure safe egress, adequate fire separation, and reliable life-safety features within single-stair configurations.
• Encourage phased adoption of single-stair guidelines through pilot projects, performance-based codes, and post-occupancy reviews.
• Promote incremental housing options on narrow lots to expand density without eroding neighborhood character.

 
Here is the source article for this story: How to get better designs for new housing in S.F.