Rule Changes From AB 835 in California Could Shift the Multifamily Market in Big Ways

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A stairway to heaven? Maybe. Higher cash flow for California landlords might be as simple as changing the number of enclosed staircases required in small multifamily buildings. 

That’s the debate surrounding Assembly Bill 835. California’s fire marshal is finalizing a report to comply with the bill and potentially reshape real estate investment across the state.

Why Staircase Rules Matter to Small Landlords

Under today’s International Building Code, which is followed in some capacity by most U.S. jurisdictions, buildings above three units must include at least two enclosed staircases, which shape the core of any apartment building. Assembly Bill 835 seeks to allow single-stair multifamily buildings with more than three units.

The proposed ruling is by no means unique in America. Many jurisdictions, including Seattle and New York, allow single-family staircase buildings (up to six units). It is, however, a financial game-changer for small landlords, as California YIMBY’s website explains, reducing construction costs, creating more livable square footage, and allowing apartment buildings to be constructed on smaller, narrower, and oddly shaped lots. More apartments equal more cash flow.

AB 835’s author, Assemblymember Alex Lee, sees the bill as opening more sites rather than a dramatic rewrite of the code. Lee told Mitpitasbeat:

“I see AB 835 as a first step to revising California’s building code on apartment staircases. If California were to permit single?staircase apartments above three stories, we could unlock previously undevelopable properties and create more high-density housing. Single?stair apartments also allow for more efficient use of building spaces, along with a greater variety of housing units.” 

In practical terms, eliminating an extra staircase could create more usable exterior space, provide sorely needed extra parking, and facilitate higher rents and lower tenant turnover.

The Opposition

The Pew Charitable Trusts estimates that single-stair four-to-six-unit buildings with relatively small floor plans cost roughly 6% to 13% less to build than comparable dual-stair designs, partly because they sit on narrower lots and use simpler cores. In addition, Pew states that safety is not compromised by eliminating the second staircase.

National Fire Protection Association president Jim Pauley stated, however, that safety records could not be viewed uniformly, saying, “While the report celebrates the outcome of modern safety codes, it could also be used to open the door wider to bypassing the very process that developed them,” pointing out that well-funded fire departments in New York and Seattle, which both allow a single exit staircase in buildings up to four stories under their respective codes, allow for much faster response times than elsewhere in the country.

Fire unions have taken a harder line. The International Association of Fire Fighters (IAFF) has launched campaigns in various U.S. states and cities, including Los Angeles and Connecticut, arguing that single exit designs “jeopardize escape routes and complicate firefighter response.” In short, they claim affordability should not come before safety.

“We all want to see more affordable housing built, but not at the expense of people’s lives,” General President Edward Kelly said on the IAFF website. “One stairwell means one way in and one way out. When firefighters are going up and families are trying to get down, that’s a recipe for disaster.”

His sentiments were echoed by IAFF General Secretary-Treasurer Frank Líma, who stated: 

“The removal of a second stairway as an emergency exit—a critical life safety feature—is not an acceptable trade-off for additional housing. That’s the bottom line. The proponents of this ‘only one way out’ design have an overreliance on fire alarms and sprinklers to perform without fail. And that’s a big gamble on public safety.”  

More Tech, Building Codes, and Safer Units

Advocates of single-staircase multifamily buildings point to increased safety standards and building codes, which have resulted in fewer fires. “New fire safety standards in our building code have made it so new buildings are much safer overall,” Los Angeles council member Nithya Raman said in support of considering the change.

As with many issues, the case for building code reform has ultimately become political: Advocates of an outright gas stove ban—often the cause of fires in apartment buildings—in favor of electrification have come up against the oil and gas industry, supported by the Trump administration.

Other States Are Following Suit

The single-staircase argument is being adopted elsewhere. Colorado, Pennsylvania, Rhode Island, Minnesota, Oregon, Virginia, and Washington state have already adopted some form of single-staircase allowance for buildings over three stories, with some limitations tied to building size, according to Pew.

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The Push for Greater Housing Supply

The 2027 edition of the International Building Code is expected to ratify the single staircase for apartments up to four stories, under certain defined limits, according to Boston Indicators and other sources. The pressure to increase housing supply and staunch the affordability crisis by expanding the number of permissible units in small multifamily buildings has been a central argument for zoning reform advocates, keen to end single-family-zoned neighborhoods.

As Single-Family Stalls, Multifamily Housing Takes on More Importance

Single-family housing starts hit an 11-month low in mid-2025 amid higher borrowing and construction costs, underscoring the importance of maximizing multifamily housing. Conversely, multifamily starts soared 30.6% in June compared with the previous year, with all regions except the Midwest reporting stronger multifamily gains, according to KPMG Economics, which summarized National Association of Home Builders data.

Final Thoughts: Practical Strategies for Landlords to Increase Cash Flow in Small Multifamily Buildings

Even if building code reform is successful in advocating for single staircases in small multifamily buildings, retrofitting apartment buildings accordingly is usually far more expensive than it’s worth. 

However, there are more practical ways to increase cash flow with your existing multifamily units. These include:

Adding ADUs: If zoning and space allow it, adding an ADU on your existing lot is a relatively easy way to generate more cash flow without getting involved in major construction.

Take advantage of “missing middle” housing reforms: Zoning changes in some U.S. cities have legalized duplexes, triplexes, and fourplexes in heavily residential districts, often removing parking minimums to allow more units.

Implement a classic value-add strategy: Upgrading kitchens and bathrooms is a proven way to increase rents, especially for landlords with under-rented buildings in rapidly appreciating neighborhoods.

Upgrades and separating utilities: If practical, adding in unit laundry rooms, upgrading parking facilities, implementing a ratio utility billing system (RUBS), and sub-metering systems where it’s allowed are all practical, relatively easy ways to increase cash flow.