New Book Reveals Reasons for National Obsession with ADUs

Exorbitant housing costs, a growing desire for multigenerational living, and the “simple living” trend have elevated accessory dwelling units as a viable housing alternative for all demographics.

ADUs have been around forever: tiny abodes atop garages on alley-loaded properties … intriguing cottages tucked behind grander houses … miniature structures mimicking the mother house connected by a walkway. When you look closely, particularly in neighborhoods built before the 1950s, you will see them everywhere. 

Today, as Sheri Koones details in her new book ADUs: The Perfect Housing Solution, this flexible housing type has become a powerful and popular solution for today’s housing crisis. An Accessory Dwelling Unit (ADU) is a smaller house built on the same lot as a primary dwelling — also known as a granny flat, accessory structure, guest house, carriage house, or the romantically named laneway house.


ADUs: A Tidal Wave Coming?

There’s no need to describe the housing affordability crisis. It has been heavily covered in the news and experienced in real life by every person currently jockeying for a place to live. 

But the coverage is getting more dire: The New York Times dubs the move by all demographics to small (as in 400-square-foot) housing as “The Great Compression” and CNN, which did a tough-to-read report on the housing ownership crisis experienced by young people, says “the quintessential dream of owning a home is slipping away.”

These examples are why when I asked Koones who is willing to live in an ADU, she didn’t miss a beat: “Everybody.”


This A-frame charmer was built by a single property owner who uses it for rental income.

Motivations Behind ADU Living

“A lot of people looking for housing don’t want high-rises or condos—and with kids that is impossible and too expensive,” she says. “Then you have the kids coming out of school with huge school loans and a large aging population that doesn’t want to go to senior facilities. Years ago, people were old when they hit their  60s and 70s. Today they are vital, and they want to be close to their kids or grandkids—or simply live comfortably with less overhead and cost.”

Two of the houses Koones covers in her book are multigenerational living situations. “Multigenerational living is so popular now,” Koones says “The younger people can live in the ADU before they have children, and then, when they have kids, swap places with their aging parents.”

One multigenerational house Koones features reinvents the concept of a big-house-with-small-house model. “This is a fantastic house where the two units are next to each other and connected by a porch in the center where the family members can meet,” Koones explains. 

Koones details other interesting housing scenarios both from an architectural standpoint and an everyday living standpoint. 

“Many people like ADUs for the extra space or rental income. One woman used it to practice her acting scripts, alternating time with her husband who used it as an office,” Koones says. “Others don’t need a large house but don’t want to live in a large multiplex. They want to live privately, hidden from the street.” 

ADU Costs and Values

The important question regarding how much it costs to build an ADU vexed Koones throughout her research: “People were more willing to give me the most personal details about their lives—like that they were trying to get pregnant—than they were willing to talk about costs!”

This is most likely because building anything today is costly, from materials to labor. And, if you use the outdated model of calculating cost per square foot, a 300-square-foot unit is going to come out much higher than a larger footprint house. 

And while ADUs may come on “free” land, they still require foundations, utility connections, hardscaping/landscaping, and permits. While Koones noted many of the ADUs hook into the main house to access plumbing, electricity, and sewer, others were separately metered. 

The value of adding an ADU to a property is similarly murky because it depends on the area you are building in, with it adding more value in more dense areas where housing stock is tight and therefore expensive. 

Koones’ best estimate from her research indicates that an ADU adds about 15% to the value of a property. She reports that many realtors are now including information in their listings about the potential of adding an ADU to a property. Appraisers, as usual, will be slower to pick up the value, but as properties with ADUs turn over, their value will be realized. 

Plus, like everything else in real estate, it doesn’t matter what you pay for a property, it’s what you eventually sell (or rent) it for that matters—or, in the case of ADUs, how important the property is for your business or lifestyle. 

When you consider the goals of many of the subjects of this book, the initial cost of building an ADU was probably not the only consideration. They also weighed how the ADU could enable a lifestyle with invaluable perks like childcare, elder care, shared cooking opportunities, and housework and property maintenance assistance. 

For today’s time- and cash-strapped youth and families, these perks are gold. For seniors, it can mean the difference between a richly lived life with family and counting down the days in a nursing facility. 


In this side-by-side arrangement, the porch is where two lifestyles meet. The grandparents travel, so they live in the “ADU side” (left). They can babysit their grandchildren and have meals  with the whole family.

ADUs: Small Footprint, Big Lifestyle

ADUs_cover_copyWith this book, Koones provides a valuable national collection of beautiful inspiration and lifestyle ideas as opposed to a how-to book on building an ADU yourself. 

Resources include lists of architects, builders, and products. She addresses pre-built versus custom and what to consider before you build an ADU. From a green standpoint, Koones explains the importance of blower door testing, sustainability, and all-electric living. 

The ADU shown as the featured image at the beginning of this article is a 350-square-foot unit over a garage. “It is so pretty and light,” Koones points out, summarizing why ADUs have captured the hearts of many people. “This ADU has everything you need—living space and sleeping areas plus storage—and is quite beautiful. It is amazing what you can do with a small space and skylights.”

The book is available March 19. You can preorder this and Koone’s other housing-related books at Chapters, Barnes & Noble, and Amazon or by placing an order through your local bookstore. 

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