Michigan Opens the Door to 4-Story Single-Stair Apartments

Nora Whitman

When Michigan Governor Whitmer sat down to sign House Bills 5570 and 5571, turn, turning them into Public Acts 28 and 29, she wasn't just updating paperwork. Brought to you by Jellypod AI, this stroke of a pen officially amended the Single State Construction Code to allow for residential buildings to be built up to 4 stories with just a single staircase. Now, if you spend your days in city council chambers like I do, you know that building codes usually get zero attention compared to big, noisy zoning fights. But this, this right here, is quietly one of the biggest policy shifts for housing supply we have seen in years.

Nora Whitman

To really understand why this matters, you have to look at the geometry of a standard small apartment building. Under old rules, if you wanted to build, say, an eight to sixteen unit building on a narrow lot in a downtown area, you were required to build two separate exit staircases, connected by a long double loaded corridor running down the center. That double corridor design wastes up to 15% of the usable floor area just on duplicate exit shafts and dark hallway space. And, and on a narrow fifty foot city lot, fitting two stairs means you literally cannot build at all. It forces developers to assemble massive lots and build giant, blocky complexes instead of small, charming infill homes. It was a massive economic bottleneck.

Nora Whitman

What makes this Michigan win so remarkable is how it actually passed. It was a bipartisan breakthrough led by Republican Representative Parker Fairbairn from Harbor Springs and Democratic Representative Stephen Wooden from Grand Rapids. They brought together real estate builders, urban planners, and housing advocates. And the data they brought to the table showed that allowing an option to build midrise apartment buildings of up to four stories cuts direct construction costs by anywhere from 10% to 13% per project. Think about that for a second. Ten to thirteen percent off construction costs without spending a single dollar of taxpayer subsidies, just by eliminating an unnecessary duplicate stair requirement on midrise buildings.

Nora Whitman

I, I, I have covered urban planning for over a decade now, and I can tell you that we spend so much energy arguing over upzoning and single family land use. But building code details are the, the actual missing link. Single stair designs are standard across Europe and Asia, and they allow for larger family sized apartments with windows on multiple sides, better cross ventilation, and beautiful, walkable urban architecture. Removing this hurdle opens up all those awkward, narrow, underutilized urban lots that developers have had to ignore for decades.

Nora Whitman

Now, let's unpack how Public Acts 28 and 29 actually work on the ground. The state code update raises the single exit cap from three stories up to four stories. But it does not mean life safety is being compromised, er, far from it. To use the single stair option, buildings must include robust mandatory life safety features, like automated sprinkler systems and fire rated enclosure barriers. The state provides standardized guidelines across all jurisdictions, so builders do not have to guess what individual inspectors will require.

Nora Whitman

However, there is a crucial catch that every local advocate needs to keep in mind. The state construction code change legalizes the single stair building design, but local municipalities still retain their underlying zoning authority over maximum building height. So if your city's local zoning ordinance limits a neighborhood to two stories, Public Act 28 will not automatically override that local height limit. Cities will still need to update their own land use maps to allow four story heights if they want to see these cost effective midrises built on their main streets.

Nora Whitman

Moving on to a few quick hits from across the country. First, down in Maryland, Howard County Executive signed Council Bill 3 2026, also known as ZRA 218. This measure is expanding opportunities for the construction of accessory dwelling units by eliminating rigid minimum lot size requirements and relaxing setback restrictions across the county. It makes it dramatically easier for homeowners to build backyard cottages or garage apartments for aging family members or renters.

Nora Whitman

Meanwhile, in Illinois, state lawmakers are advancing House Bill 1814. This bill aims to legalize multi family missing middle housing, like duplexes, triplexes, and fourplexes, by right on lots currently zoned exclusively for single family homes in municipalities with populations over 10,000 residents. It is part of a growing national trend of state level intervention in local land use controls.

Nora Whitman

And finally, back in Michigan, lawmakers passed companion legislation in House Bill 6074, signed as Public Act 32. This act places a 100 home cap on large institutional investor acquisitions of single family homes within the state. The goal is to prevent massive private equity firms from buying up neighborhood housing stock and pricing out first time homebuyers. It is a fascinating double strategy in Michigan, expanding missing middle supply on one end while curbing speculative corporate buys on the other. A busy week for housing policy, to say the least. That is all for today, talk soon.