Once a garage, this cottage outside Seattle is an example of an accessory dwelling unit, or ADU. Younger homeowners who want to accommodate a parent — or older homeowners who want to create a space for a caregiver — may consider adding a tiny home or wing to their property, or redesigning a basement or attic space as an ADU. Photo by Sightline Institute Modest Middle Homes Library

• Share

PRINT

When Cary Childre, 65, of Athens, Georgia, considered moving closer to her daughter, Eva Maudlin, of Decatur, an Atlanta suburb, she realized she couldn’t afford to buy “much of anything.”

So, Maudlin, 31, researched building a cottage in her own backyard. In October, they made a deposit on a Craftsman-style design by a local architect who will manage the project from permits to completion. The 429-square-foot home will have one bedroom and bathroom, a galley kitchen and living area, and a small covered porch.

Fueled by an aging population and a scarcity of affordable housing, accessory dwelling units (ADUs) are a hot new trend in multigenerational living. You may know them better as in-law suites, garage apartments, carriage houses, casitas and granny flats. Freddie Mac said the share of for-sale listings with an ADU has risen 8.6% year-over-year since 2009.

These units can be created by finishing a basement or attic, converting a garage, reconfiguring unused space, adding on, custom building a detached unit, or installing a prefab one.

Over time, you could rent the ADU for income; house a parent, child or caregiver; downsize into it yourself and rent the main house, or make it into an office or guest quarters.

Wide variety of options

How much you’ll spend varies by city, type and degree of customization, said Kol Peterson, an ADU advocate and consultant in Portland, Oregon. He said he’s seen the cost range from $20,000 for a basement unit to more than $400,000 for one built above a garage.

He offers a few rules of thumb wherever you live: The higher the cost of housing, the higher the cost of construction.

And, converting existing space is cheaper than building a detached unit.

But if you are building something separate, because of the fixed costs required to build a detached home of any size, a larger unit will be only marginally more expensive than a smaller one. So, he recommends building up to the largest allowable size.

A prefab ADU is cheaper and quicker to install than one built on site, but a custom design lets you include aging-in-place features, such as a step-free entry, wider doorways and a curb-less shower. If you hire a design-builder, look for an aging-in-place specialist certified by the National Association of Home Builders.

Be sure to enable privacy

An ADU in your existing home should allow its residents to have privacy so they will feel at home, not like a visitor or intruder, said Michael K. Lenahen, an architect and president of Aurora Builders, in Jacksonville, Florida.

Consider creating a private entrance and adding soundproofing to the shared walls of an in-law suite. Sitting areas indoors and outdoors will allow you or a parent to enjoy solitude, entertain friends without asking for permission, and avoid feeling confined.

Most homeowners pay for their ADUs with cash, home equity borrowing or a cash-out refinance. Other options include a construction loan or renovation mortgage for purchase or refinance backed by Fannie Mae or Freddie Mac.

The simplest, but most expensive, option is an uncollateralized personal loan of up to $100,000 from online lenders LightStream or SoFi.

When Childre’s cottage is ready, she expects to sell her home for about $300,000, pay $190,000 for the cottage in her daughter’s backyard, and stash the rest for future needs. Mother and daughter look forward to living footsteps away.

Before you invest your nest egg to create an ADU on a child’s property, consider how you will pay for the care you will inevitably need someday, said Lisa Mayfield, a certified care manager and past president of the Aging Life Care Association.

You can’t sell the ADU to raise funds, and renting it out after you’ve moved elsewhere is unlikely to cover the cost of your care, said Angela Macey-Cushman, who practices elder law in Seattle.

Plus, if you give a child money to build an ADU within five years (30 months in California) of applying for Medicaid, you could be penalized with delayed coverage.

Note: Accessory dwelling units are legal in Baltimore County and Howard County but not in the city of Baltimore.

© 2021 The Kiplinger Washington Editors, Inc. Distributed by Tribune Content Agency, LLC.