How Single-Family Conversions Benefit Both Homeowners and Cities

Converting single-family homes to triplexes can ease the housing crisis and offer affordable, flexible options for more households. Why is it largely illegal?

1 minute read

March 4, 2025, 10:00 AM PST

By Diana Ionescu @aworkoffiction


Two pastel green/blue front doors on duplex with decorative wreaths.

Jason / Adobe Stock

A “Multigenerational Roommate House” outside of Dallas offers a model for affordable multifamily housing — if only it’s made legal in more places.

The home’s owner, Monte Anderson, “applied some savvy interpretation of local zoning rules to transform it into a legal, owner-occupied, multiunit home for five single adults ranging in age from almost twenty to over 70.” The units have separate entrances, bathrooms, and kitchenettes (full kitchens would trigger a zoning violation).

This style of housing is illegal under most U.S. zoning codes, explains Lauren Ronnander in an article for Strong Towns. But advocates for reform argue that allowing single-family conversions to duplexes or triplexes “can give residents the flexibility to live where they want at a price they can afford.”

According to Ronnander, allowing duplex conversions can also raise property values and, in turn, local tax revenue, benefiting cities. “In cities that make this type of housing legal by right, thousands of stagnant properties can be improved, raising property values, increasing tax revenue and revitalizing aging neighborhoods.” Legalizing single-family conversions can create more housing choices while avoiding the opposition and infrastructure costs that come with larger multifamily projects.

Monday, March 3, 2025 in Strong Towns

Young Professional

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban and Environmental Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban and Environmental Planner

Get top-rated, practical training for planners

Overlapping highways

The state-sanctioned urbicide of Austin

People don’t kill cities. Freeways do.

September 8, 2026 - Benjamin Schneider

The Hoover Dam blocking the Colorado River. The river's water level is noticeably low. The cliffs surrounding the blue water are brown and jagged.

US to reduce Colorado River water deliveries to Mexico

A new Colorado Treaty amendment reduces Mexico’s Colorado River water allocation by 250,000 acre feet.

September 11, 2026 - The Arizona Republic

Skyscrapers in Jersey City.

New Jersey’s second-largest city bans standalone data centers

Jersey City will continue to allow co-location facilities, such as those meant for research institutions that store their own data.

September 4, 2026 - The Cool Down

A New Jersey train approaches people waiting at the station.

Amtrak not solely to blame for New Jersey commuter rail's unreliability, report finds

A new study from the Garden State Initiative found that NJ Transit’s budget grew 20% across a 4 year period, but reliability declined significantly over the same period.

September 15 - Mass Transit

A tall, gray power plant billows smoke into a blue sky.

EPA erases limits on planet-warming pollution from power plants

Under Monday’s plan, power plants would still have some limits on how much mercury, arsenic and other contaminants they can emit.

September 15 - New York Times

A white RAPID bus. The lower half is light blue, and says RAPID in purple text. The bus is half visible, appearing from the left side of the image.

Phoenix announces new on-demand transit service, more frequent RAPID buses

Both new services will launch in October, and are part of Phoenix's Project Effective Access Solutions for Easing Congestion.

September 15 - KJZZ

FREE Course: Walkable City 1: Why Walkability?

After describing his path towards focusing on walkability as the essence of good planning, Jeff Speck marches through his five principal reasons for making more walkable places.

Reinventing Malls: Planning Alchemy—Turning Gray Fields Into Gold

The course focuses on the opportunities and imperatives that shape reinvention of mall sites.