Day: October 10, 2026

San Francisco has revised its residential building requirements to allow certain multifamily projects to use one interior stairway paired with a secondary means of egress. The new framework applies to qualifying buildings of four to six stories, with different arrangements according to height. It gives developers additional flexibility when designing apartment buildings on constrained urban lots while retaining building safety and approval requirements.

Key Takeaways

• Qualifying four-story residential buildings may use one primary stairway with a secondary means of egress, such as a fire escape or exterior staircase
• Five- and six-story buildings may use one interior staircase and one exterior staircase instead of two interior stairways
• Buildings taller than six stories remain subject to existing two-stairway requirements
• The revised rules may provide more layout flexibility on narrow or irregular residential sites
• Developers must obtain approval for proposed alternative stairway configurations and meet applicable safety requirements

San Francisco Housing Rules Change Stairway Design Options

The revised San Francisco housing rules change the exit configurations available to certain multifamily residential projects. Buildings with three or more stories have generally been required to include two interior stairways. Under the updated approach, qualifying four- to six-story buildings can propose a single interior staircase alongside an appropriate secondary exit.

The change is particularly relevant to smaller urban parcels, where two interior staircases can constrain floor plans. A different exit arrangement may allow developers to reconsider the placement of apartments, corridors and building services within the same footprint.

The distinction between permitted designs and completed housing remains important. San Francisco’s housing development pipeline figures show that many proposed homes have yet to reach construction. More flexible stairway rules may help with some design constraints, but financing, project timing and other approvals still affect whether development proceeds.

The updated provisions are not a blanket exemption from building safety standards. Developers seeking to use the alternative configurations must submit their proposals to the Department of Building Inspection for review. Eligibility depends on building height, the proposed means of egress and compliance with other applicable requirements.

New Rules Set Egress Standards for Four- to Six-Story Buildings

The revised framework establishes different stairway arrangements based on building height. Each configuration retains a secondary means of egress and remains subject to project-specific review.

Four-Story Residential Buildings

Qualifying four-story buildings may use one primary interior staircase and a secondary exit, such as a fire escape or exterior staircase. This provides an alternative to placing two stairways inside the building.

The secondary egress route remains a required part of the proposed design. Developers must account for its location, access and compliance with applicable safety standards when preparing plans for review.

Five- and Six-Story Residential Buildings

Five- and six-story residential buildings may use one primary interior staircase and one exterior staircase instead of two interior stairways. The exterior staircase serves as the additional exit and must be incorporated into a compliant building design.

This arrangement changes where a stairway can be located rather than eliminating the need for a second staircase. Its effect on usable floor area will depend on the site’s dimensions and the space needed for the exterior exit.

Buildings Taller Than Six Stories

Buildings above six stories remain subject to the existing requirement for two stairways. The alternatives for qualifying mid-rise buildings do not extend automatically to taller residential projects.

Developers must establish the appropriate requirements for the proposed building’s height and configuration before relying on a revised stairway layout.

Single-Stair Designs Expand Multifamily Development Options

Stairways take up space that might otherwise be used for apartments, corridors or other building functions. Their number and placement can influence the size and shape of residential units, the length of shared hallways and the amount of usable floor area on each level.

Allowing a single interior staircase in qualifying buildings gives architects additional options when working with narrow or irregular parcels. Depending on the site, an alternative layout may allow more efficient circulation or greater flexibility in arranging apartments.

Building design is only one part of the broader development framework. The city’s revised transit housing strategy addresses where transit-related housing density standards may apply, while the new stairway provisions focus on how eligible buildings can be configured.

The flexibility is particularly relevant to sites where stairs, elevators, corridors, utilities and required exits must fit within a limited footprint. Changing the location of one stairway can affect the arrangement of those elements, though the effect will differ from project to project.

The rules do not automatically make every constrained parcel suitable for residential construction. Lot dimensions, fire protection, accessibility, structural design and zoning restrictions still determine whether a proposed building is feasible. Developers must also assess costs, financing and the approvals needed to move forward.

Construction Costs and Floor-Plan Flexibility Shape the Reform

The number and location of stairways can affect more than the space occupied by the stairs themselves. A second interior staircase may influence corridor layouts, apartment entrances, structural arrangements and the distribution of usable floor area.

When the revised rules permit a different configuration, project teams can evaluate whether moving a stairway outside improves the floor plan. The outcome depends on building dimensions, the required exit route and other design conditions.

The reform may reduce some space and construction constraints, but cost savings are not automatic. Five- and six-story buildings still need an exterior staircase, which requires space, materials and code-compliant access. A project’s total cost also depends on structural systems, elevators, fire protection, utilities, labor and financing.

For developers and property owners, the relevant question is whether the alternative stairway arrangement produces a workable design that meets safety standards and financial requirements. The revised rules expand the available options without establishing a uniform cost reduction for every qualifying project.

Building Safety and Permit Reviews Still Apply

The revised stairway rules provide additional design choices rather than remove the need for building review. Residential proposals must continue to satisfy the fire and life-safety requirements that apply to their height, layout and intended use.

A secondary exit remains central to any proposed single-interior-stair design. Four-story projects may use an approved secondary egress arrangement, while five- and six-story projects must account for the exterior staircase specified under the new framework.

Developers must submit proposed alternative layouts for review by the Department of Building Inspection. The department’s approval of a stairway arrangement does not replace other planning, permitting or construction requirements.

The practical impact will depend on how individual projects use the added flexibility. The reform may make certain mid-rise layouts easier to pursue, but each project must still demonstrate compliance before construction can begin.

Frequently Asked Questions

What Are San Francisco’s Revised Single-Stair Building Rules?

The revised rules allow certain multifamily buildings of four to six stories to propose one interior staircase with an approved secondary means of egress. The permitted arrangement varies by building height and remains subject to safety review.

Which Residential Buildings Qualify for the New Stairway Requirements?

The alternative configurations apply to qualifying four-, five- and six-story residential buildings. Eligibility depends on the proposed design, building height and applicable code requirements.

How Do the Rules Differ for Four-, Five- and Six-Story Buildings?

Four-story buildings may use one primary staircase with a secondary exit such as a fire escape or exterior stair. Five- and six-story buildings may use one interior staircase paired with a compliant exterior staircase.

Do the Revised Rules Eliminate Secondary Egress Requirements?

No. Qualifying buildings must retain a secondary means of egress. The permitted form of that exit depends on the building’s height and the applicable safety standards.

Can Developers Begin Construction Under the Revised Rules Immediately?

The rule change does not authorize construction on its own. Developers must obtain approval for any proposed alternative stairway configuration and complete the applicable planning and building permit processes before work can begin.