Housing Design Has to Evolve

In 2001, a good friend became pregnant with twins. As a single parent, she decided to move into a newly established co-living compound, which she hoped would provide support and company as she raised her new family. A seem­ingly radical idea nearly 25 years ago, co-living—a housing approach that offers a combination of private and shared space—is now a fast-growing market. Its increasing popularity under­lines an obvious truth about housing in America: Our household demographics are changing, and our housing designs need to change too.

Since World War II, most housing in America has been built to support a nuclear family structure: two parents living with their children. But in the last several decades, family structures have evolved to include fewer nuclear families and more single-parent families, intergeneration­al families, nonfamily groups, and downsizing or unrelated seniors. As the American family evolves, housing design must evolve with it.

In cities and towns large and small, commu­nities are struggling to provide adequate and affordable housing that meets the varied needs of today’s population. Changing the way we design houses—and offering more housing choice at more price points—will not only better meet the needs of our evolving house­holds, it will also help provide more affordable and attainable options, which will lead to more stable, thriving, and sustainable communities.

Changing Demographics

In the era after World War II, the majority of the adult American population was married: 87 percent in 1950. By 2022, that figured had dropped to 47 percent. The same time period saw a dramatic rise in people living alone, growing to almost 28 percent of the population in 2023 from less than 10 percent in 1950. US Census statistics from 2022 tell us that American households are now just as likely to include single-parent families (31 percent), extended or multigenera­tional families (8.1 percent), families without children (36 percent) or stepfamilies whose household size changes weekly based on custody schedules, and nonfamily groups (8 percent).

 

 

Economic factors are also changing housing needs. Baby boomers, numbering more than 76 million, are finding that aging in place in car-centered exurbs is more difficult than they thought. Many who can afford to move also want to downsize. Millennials (representing almost 22 percent of the population) and Gen Z (representing more than 20 percent in 2023) are struggling to launch careers and pay off college debt, and are slower than previous generations to marry or have children. Homeownership is lower for these generations than it was for previous generations due to factors including a high debt-to-pay ratio, low inventory, and high interest rates.

Finally, most cities in the US are facing an incredible housing shortage, which drives demand and prices for the available housing stock. Estimates suggest that the US is currently short approximately 4.5 million to 5 million homes. The stock that does exist provides little variety or flexibility. In 2023, around 1.45 million homes were built; that included one million single-family units and about 450,000 multifamily units.

These forces are prompting an urgent examination of how local governments can incentivize new housing, including housing designs that better accommodate how people are living now.

Evolving Housing Design

Since the post–World War II era, the housing market has been dominated by single-family homes. This was due in large part to local and federal policies that supported the creation of suburban neighborhoods through disinvestment in downtown neighborhoods by redlining practices and transit disinvestment, new highway investments, and the marketing of the “American Dream” targeted to returning service members. Little has changed in the last 50 years.

The lack of variety and stagnant housing design contribute to the national housing shortage as people are forced to live in housing situations that fail to meet their needs. To better meet the housing needs of the 21st century, builders, developers, and local governments should offer a wider range of choice and variety. Expanding housing designs will not only help increase the housing supply, it will also enable more people to live as they want and choose.

1. Restore the boarding house. Traditionally, the boarding house was a transitory step between family life and independence. Boarding houses offered meals and housekeep­ing, providing a valuable housing option for single adults. During the 19th and early 20th centuries, between one-fourth and one-third of urban households took in boarders. However, after World War I, boarding houses morphed into single-room occupancy (SRO) units, which became associated with low-income housing. As such, many local governments put significant zoning restrictions on where and how they could be built. Approximately one million SRO units were demolished in major cities between 1960 and 1980, including Chicago, New York, Denver, Seattle, and San Diego.

That negative perception is slowly changing as more businesses realize the value of—and demand for—housing with shared amenities. A global company called Cohabs offers co-living for people 18 or older in shared homes in New York, London, Brussels, and Paris, among other cities. In 2024, the company opened 16 houses in the NYC area and 36 rooms in DC, with plans to increase supply to 500 or even 1,000 beds.

Each tenant has their own bedroom, which comes furnished with a bed, desk, and safe, and bathrooms are shared by up to three people. The kitchens—a central one on the first floor and a smaller one on each floor above—have dishes and basic provisions. Each tenant gets a shelf in a refrigerator, as well as a locker to use as a pantry. The common areas include living rooms, work­spaces, a movie room, a gym, and a laundry room, as well as an outdoor terrace and a roof deck.

 

 

The growth of co-living arrangements is predicted to significantly increase, with esti­mates suggesting the market will grow from $13.3 billion to $63.8 billion by 2028. As housing in urban areas becomes more expensive, co-living offers an affordable alternative, especially for young professionals and students. By sharing living spaces and communal facilities, residents can significantly reduce expenses such as rent, utilities, and maintenance.

The demand for all types of living space is in many places matched by an enormous potential supply. Large old homes can easily be converted into co-living spaces. To facilitate these conver­sions, in 2022, the City of Toronto legalized rooming houses citywide. Expanding the design options for the boarding house and enabling homeowners to legally transform their houses could be a sustainable business model; it could also provide a housing alternative in cities and towns of all sizes, providing income for home­owners and much-needed housing for renters.

2. Expand the boarding house concept. In addition to retrofitting existing homes, some developers are meeting the demand for boarding houses with new builds. Eli Spevak, a developer in Portland, Oregon, is integrating the boarding house model into his practice. His Flora and Ulysses Courtyard Co-Living model comprises two side-by-side structures, each consisting of a primary home and an accessory dwelling unit (ADU), that share a central courtyard. The structures are built on adjacent standard-sized lots, creating an alternative housing option within existing residential zoning regulations. Each side has a common area with a living room and kitchen on the ground floor. Space for smaller social gatherings is available on the ground floors of the ADU and on the second-floor decks overlooking the courtyard. The Flora and Ulysses offers one-bedroom and two-bedroom options.

Renters are selected carefully—within the parameters of fair housing laws—to ensure a safe, welcoming, and supportive community. When an opening arises, existing residents give tours and make recommenda­tions to the management company. The on-site manager, who is a resident and receives a slight rent discount, manages and facilitates this process.

 

 

This raises a critical point: This type of housing can come with unconventional manage­ment responsibilities. Most management companies are not set up or even prepared to navigate the process of facilitating community. When neighbors share a large kitchen or even a courtyard, their relationships become essential. In fact, these living situations can succeed or fail based on the connections among the people living in them.

Some new houses include living spaces that are designed to be more separate from the rest of the house; these could be used by an aging parent, a returning college student, or a tenant, or all three over time. These spaces are generally not considered legally separate units and often have built-in amenities, so the space could be used as an entertainment area or as a short- or long-term rental.

As housing stock continues to be constrained in many cities, the traditional and expanded boarding house concept can offer immediate housing options for a number of demographic populations. To facilitate an expansion of these options, local governments would need to modify or change zoning codes that currently prohibit or limit them.

3. Legalize and incentivize ADUs. Accessory dwelling units (ADUs), sometimes referred to as granny flats, come in many forms. They can be created by building a basement apartment, modifying the space above a garage, or even constructing a backyard cottage. These units can help increase the housing in a neigh­borhood by integrating into the existing fabric and using existing infrastructure. Additionally, they can provide an income stream for homeown­ers, which in turn can help residents age in place or enable a home purchase.

Many local and state governments are taking steps to legalize ADUs, as these smaller living spaces can provide more affordable housing in high-demand areas. In 2023, the ADU market was $16.5 million, and it is projected to more than double by 2032.

Santa Cruz, California, was one of the first municipalities to make ADUs easier to build. The city revised its zoning ordinance to eliminate a parking requirement for single-family homes, which freed up space for accessory units. In addition, the revision included design elements that ensure ADUs complement the surrounding homes. Seven architects designed compact building prototypes (500 square feet) that address a variety of site needs. These plans were pre-reviewed by city departments, and homeowners can select from any of these designs to expedite the permitting process and reduce planning and design costs.

Santa Cruz was on the forefront of broader legislative reform allowing ADUs in California, which led to a 15,334 percent increase in permits between 2016 and 2022, resulting in nearly 84,000 completed units. Seattle followed a similar regulatory path, and by 2022, construc­tion of ADUs had outpaced construction of single-family homes in the city.

 

 

In most places, however, the promise of ADUs has not been fully realized. While these accessory units are now legal in many communi­ties, local governments are often imposing significant requirements, such as dictating the minimum lot size or limiting ADU residents to relatives of the homeowner. Even when these restrictions are removed, the cost of building a small, simple backyard cottage can easily exceed $300 per square foot, which puts it out of reach for many homeowners.

Given the current suburban landscape, integrating ADUs into existing neighborhoods represents an incredible opportunity for local governments to increase housing supply. To maximize the potential of this housing model, local governments should simplify and stream­line ADU regulations, work with architects and designers to develop preapproved designs, and offer incentives such as five years of reduced property taxes to help offset the construction cost burden to the homeowners.

4. Expand intentional living communities. The hippie communes of the 1960s and 1970s have given way to intentional living compounds, which consist of a group of people who choose to live together or share resources based on common values. Intentional communities usually consist of a small number of apartments or single-family homes built around central squares or common spaces; they operate with a focus on connection, often including weekly dinners at a community center or other common area, shared babysitting services, and shared gardens or games. They are rising in popularity as a way to save money, create community, and reduce the stress of modern living. Such a living situation is especially attractive to young families, single-parent households, empty nesters, and seniors who are still living independently and want to combat isolation.

It’s hard to gauge how many people live in intentional communities, as they can be anything from friends living together with an open-door policy for each apartment to urban developments designed to house multiple families. The Founda­tion for Intentional Community estimates that 10,000 to 30,000 intentional communities likely exist worldwide. One of the greatest attributes of intentional communities is that they can be formed within existing building stock (e.g., a duplex or other multifamily configuration), or be designed and built to meet specific population needs and values.

Intentional communities can range from those created around a singular purpose—such as Arcosanti, an Arizona community whose founding “arcology” concept mixes architecture and ecology to minimize the impact of human-built structures on the environment—to more organized social communities such as Takoma Village Cohousing in Washington, DC, where my friend with twins moved. In some cases, two or three families buy a multifamily house together, where each manages their own unit but they live together as a community.

Intentional communities are also well suited for seniors. Rushall Park, a retirement village in North Fitzroy, Australia, provides independent and assisted living accommodation and support. Unlike most assisted living communities in the US, Rushall Park has exceptional architecture and community design, which enables seniors to live in their own houses. The homes are located near public transit, shops, restaurants, and medical centers. The community center includes a communal dining room, activities area, informal sitting room, and library.

At a time when senior living options are both expensive and unappealing, creating a family compound can provide support for aging seniors, growing young families, and young adults. Some organizations have turned to well-planned “multigenerational villages” to help simultane­ously support aging seniors and foster children. Hope Meadows, established in 1994 on a former military base in Rantoul, Illinois, was the first to provide a place for foster families with similar challenges to share resources and experiences, and to live among older adults who needed community and could support families with their time, skills, and care. Inspired by Hope Meadows, the Treehouse Foundation created a community to support foster families and older adults in Easthampton, Massachusetts.

Blue Zones, LLC, an organization that studies place-based longevity, has researched the effects of multigenerational living, finding that children who live with—or who have frequent contact with—their grandparents have lower rates of disease and mortality. The research also suggest­ed that grandparents who care for their grandchil­dren can increase their longevity. This may be because the grandparent stays more active and engaged. (Ed. note: The author formerly served in a leadership role at Blue Zones, LLC.)

Realtors can help facilitate intentional and multigenerational communities by identifying and marketing existing housing structures that could easily be divided into separate units. Local governments can also support intentional communities by streamlining permit require­ments for developers. Given increasing housing costs, the isolation many people experience, and the documented health impacts from loneliness, supporting and facilitating intentional living arrangements can ease housing shortages as well as improve quality of life.

5. Encourage cottage courts. While intentional communities can be created within existing housing stock and have the expectation of integrated community, cottage courts are small groupings of housing around a shared public space that offer more independent living. Cottage courts can be built in urban, suburban, or rural contexts, and offered as for-sale or rental units.

In some communities, a cottage court can be built as of right in areas with multifamily zoning. With the right design, a cottage court can achieve the same 14 to 16 dwelling units per acre as a group of two-story “garden apartments,” with buildings that are more easily accepted by neighbors than generic apartment buildings.

Even with multifamily zoning, cottage courts are still not permitted by many municipalities. The density is higher than single-family zoning typically allows, and the units sit on a very small footprint, which often is prohibited by lot size and setback requirements. The houses tend to be smaller than average. The parking is grouped, rather than individual to each unit. Often these kinds of developments need zoning adjustments for parking, setbacks, and minimum lot sizes.

 

As with the co-living examples mentioned earlier, it’s essential to develop management mechanisms to support and facilitate commu­nity as these kinds of developments evolve and expand. For example, in one cottage court community, the common space fell into disrepair, a “tragedy of the commons” situation. In another, an owner decided to build a tall fence around their individual property, under­mining the development’s carefully designed sense of community. In many cases, transition­ing from the original residents to new owners can be especially problematic, as new residents may not necessarily be looking for community. Again, realtors can play a key role in supporting cottage courts by identifying and marketing them as properties more focused on community.

Cottage courts have incredible potential to help create supportive communities while allowing residents to maintain a high degree of independence and privacy. They could be an ideal living arrangement for seniors, single-parent households, or families looking for a supportive community in which to raise their children.

6. Support and incentivize manufactured and modular housing. Manufactured housing has been around for decades and has the potential to radically transform the housing industry by providing well designed housing at a lower cost than standard construction. Given the mass production scale, manufactured housing could be used to create the small, more flexible housing options that are increasingly in demand and discussed here.

One example is Katrina Cottages, which are small, affordable, and sturdy residences designed after Hurricane Katrina tore through the Gulf Coast in 2005. The cottages were created as a safer, more livable, and more humane alternative to the FEMA trailers provided to flood victims. The cottages were built on narrow infill lots in walkable neighbor­hoods and were assembled on site from factory-made panels. Ranging in size from 300 to 1,800 square feet, they often had two small bedrooms, a kitchenette, a full bathroom, a living room, a sleeping loft, and a full-size refrigerator. In the same vein as the Sears housing kits of the 20th century, the plans and lumber for these cottages were exclusively provided by Lowe’s, until the company discon­tinued the product in 2011.

Unfortunately, Katrina Cottages did not catch on as an alternative to disaster housing, nor for housing more broadly. In some places, the design faced pushback from local officials and potential neighbors, who viewed its size and factory origins with skepticism. This is not unusual for the manufactured housing industry, which has been burdened by outdated public perceptions about quality.

 

 

But that appears to be shifting: The quality, energy efficiency, and design of manufactured housing has evolved dramatically. In 2022, manufactured housing accounted for more than 10 percent of single-home starts in the US. Here, too, community plays a role: 31 percent of manufactured homes are placed in a community setting, and resident-owned communities are gaining momentum across the country.

In addition, more architecture and design firms are using modular techniques for larger projects. David Baker Architects, which has built modular multifamily housing throughout the San Francisco Bay Area, credits the building method for greatly reducing the project timeline of its 145-unit Tahanan building in San Francisco. In Los Angeles, the developer Thrive Living is using a modular design to build 800 rental apartments on top of a Costco, with 23 percent of the units dedicated to low-income residents.

7. Make retrofit and reuse easier. Adaptive reuse has long been a common redevel­opment strategy, but has largely been applied to former industrial buildings. But as single-family homes get larger and families decrease in size, new designs are needed to enable easier retrofits of existing homes into multiple living spaces or apartments. This is not a new concept: The New York City brownstone was originally designed as a single-family home in the early 19th century. Now, almost all of them have been converted into multiple apartments.

The large single-family homes that dominate much of the suburban landscape are primed to be retrofitted into multiple living spaces. Yet two significant barriers prevent such conversions: layouts and local zoning.

Multifamily units achieve economies of scale when essential water and sewer elements are stacked (that is, located in the same place on each floor). Modifying the designs of single-family homes can provide greater flexibility for future uses, either as stand-alone apartments for short- or long-term rental, ensuite living areas for aging parents or returning children, or even as condos or a cooperative structure that allows a single-owner property to be owned by many. Further, developing floor plans that anticipate a future redevelopment, redesign, or retrofit can not only add value for the homeowner, it can also provide maximum flexibility for residents to age in place. And that’s essential because space needs change over the course of a person’s adulthood. Many of these modifications can be done in the architectural design phase.

But these modifications need to be allowed by municipalities. In most suburban communities in the US right now, converting a single-family home to a two-family home would be illegal. Unless expressly allowed, very few developers would be willing to gamble that future zoning would allow two- or three-family homes. While many communities are now considering following the lead of cities like Minneapolis and Cambridge, which have eliminated single-family zoning, one possible intermediate step may be to allow conversions if the second unit meets certain design requirements, such as fitting into the architectural context of the neighborhood.

Local governments can also help incentivize or nudge the broader adoption of these types of retrofits by reducing fees for multiple electric systems or sewer lines for designs that support planned densification, which is a process that plans for and enables the evolution of a property or a piece of real estate. In most cases, developers will build an initial use—single-story retail, for example—because that’s what the market supports at the time of construction, but will design the first floor and utilities to accommodate future floors or expansions. Local governments can put approvals in place that accommodate future possibilities, which is essential for securing financing for the future project.

Planned densification can occur at all scales, from a single building to an entire block. A good example of large-scale densification is the Potomac Yard project in Alexandria, Virginia. The development was originally constructed as a standard strip mall in the mid-1990s, as that was the only use prevailing market trends would support. However, the county, developers, and owners were confident that once a new Metro station stop was added, the property would be primed for redevelopment. Therefore, only 20-year leases were made available for tenants. The entire area is now being redesigned into a high-density, transit-oriented development that will contain 7.5 million square feet of office, retail, and residential space, as well as open space.

Benefits of Evolving our Housing Designs

Providing development opportunities for a variety of housing types promotes diversity in housing price, style, and size. It also contributes to neighborhood stability by offering more affordable and move-up homes and accommo­dating a diverse income mix. And integrating more housing variety into existing neighborhoods gently increases density, which can lead to improvements in housing values, walkability, and social interaction.

Additionally, living in a community with greater population variety provides significant health benefits. Loneliness is quickly becoming a serious problem. It now affects half of all Americans. Lack of social connection has been found to be as dangerous as smoking up to 15 cigarettes a day.

A housing gap exists between market-rate housing and subsidized affordable housing; providing housing choices that better meet the needs of more families and individuals can reduce that gap without additional subsidy. For example, rent for a 500-square-foot ADU will be lower than for a 1,200-square-foot apartment. Co-living arrangements will often cost less due to the shared spaces such as kitchens, courtyards, and guest rooms. The gap between market-rate housing and subsidized housing can be further reduced when interiors are streamlined and made more energy efficient. Consequently, providing a variety of housing types and enabling a range of living situations creates significant economic value.

Locating these housing options in walkable areas can further support stronger local econo­mies. Walkable downtowns, town centers, and neighborhoods comprise only 1.2 percent of metropolitan land area—and 0.07 percent of total US land area—yet they generate 20 percent of the nation’s gross domestic product. Despite walkable places taking up only “a tiny sliver of land,” they have an outsized impact on the US economy. Expanding housing choice not only supports a community’s residents, it can also be good for its economy.

Legalizing Housing Variety

One of the primary reasons America has limited housing variety is zoning and building codes. In most towns and cities, land development regulations limit building types. Without regulatory reform, innovative housing designs will not be widely adopted. Cities can make it easier to build variety into the housing market through regulatory reform. For example, Colorado banned limits on household size in 2024.

“This issue is both a housing issue and a civil rights issue,” Colorado Governor Jared Polis said when he signed HB24-1007 into law, prohibiting local governments in Colorado from restricting how many unrelated roommates could live under one roof unless a strong case can be made for health, safety, or fire code needs. “For housing, the opportunity for people to officially be on the lease—it gives them protections, allows them to start establishing their credit, gives them the certainty that they get to live here.”

Additional regulations that could be modified to better support housing variety include:

• allowing boarding houses as a by-right use;
• eliminating minimum lot sizes;
• eliminating minimum parking requirements;
• legalizing ADUs and simplifying related requirements;
• adjusting sprinkler requirements for smaller multifamily buildings;
• allowing more units on a lot;
• removing provisions that prohibit inclusionary zoning;
• allowing adaptive reuse of any building for residential use; and
• allowing by-right building conversions from single units to multiple units.

Changing land development regulations and building codes provides a strong incentive to developers to build more housing variety. Updating zoning is the number one action local governments can take to promote more affordable housing.

Next Steps

The housing design changes discussed here can be built almost anywhere; for example, in a greenfield for new development or as part of an urban redevelopment project. They can be built as part of a broader community or added to an individual house or lot. To facilitate broader adoption of these housing types, cities and towns across the country should adopt a “don’t let the perfect be the enemy of the good” approach and seek to remove or modify many of the regulatory barriers that prevent wide-scale adoption.

Changing where and how housing is designed and built does not happen overnight. But local and state governments can take several incremental steps to help support the process:

• Lead with adjustments. For communities that want to unleash the market potential of evolved housing choices, the first step is to lead with adjustments, or variances, in a specific neigh­borhood or district. Instead of making wholesale zoning changes, make it easier (and less time-consuming) to apply for variances or apply zoning code changes to an overlay zone, if a particular geographic area or neighborhood would benefit from—or become more desirable with the addition of—different housing designs. (For example, in neighborhoods surrounding a university or with a fixed rail stop or a natural amenity such as a park or lake.) When several homes or neighborhoods have been successfully built with the adjustments, a local government can complete a wholesale code change to enable broader adoption.
• Establish desired outcomes. Be clear about the goal (housing variety) but don’t be too prescrip­tive (sticking to a specific kind of housing). Often a local government will modify its zoning codes to require “first-floor retail” when the desired outcome is a vibrant street experience. This one zoning change has the unintended consequence of requiring only retail, thereby limiting other activities that could serve the desired outcome.
• Establish metrics for success. This will provide information on when and how to expand zoning changes to another geographic area or to the whole city. Additionally, success metrics may vary for different stakeholders. Identifying what success means for each stakeholder group is critical.
• Use governmental tools, such as streamlined permitting or infrastructure improvements or upgrades, to incentivize the type and location of housing variety desired.
• Align political will. Knowing who is likely to support efforts to diversify housing—and who is likely to oppose it—is essential to success. Identifying champions and core supporters is critical in any effort involving housing changes. Equally important is knowing areas of opposi­tion, because that makes it possible to bring opponents into the process.

For much of the post–World War II era, this country has built the same kind of housing, either single-family homes or large apartment complexes. But well into the 21st century, cities and towns need to rethink how housing can better meet the needs of a growing and increasingly diverse population, and of the new household combinations that are increasingly common.

Developers need to rise to the challenge of building a greater variety of housing at different price points to increase our affordable and attainable housing supply. As consumers of housing, we all deserve housing that is more flexible to accommodate our changing household needs, more affordable, and more accessible.

 

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Lynn Richards has spent the last 25 years working to create more walkable, livable, and sustainable communities throughout the US. Most recently, she served as the executive vice president and chief policy and implementa­tion officer at Blue Zones, LLC. Prior to Blue Zones, she served as president and CEO of the Congress for the New Urbanism and had a distinguished career as a policy maker at the Environmental Protection Agency.

Lead image: Flora and Ulysses, a co-living project in Portland, Oregon, consists of two houses on adjacent lots, each with an attached accessory dwelling unit (ADU). The homes face each other to create a sense of community. Credit: Polyphon Architecture and Design.