When Your Parents Don't Live With You ... Yet. Should You Buy a Multigenerational House?

For many, the thought of having parents, in-laws or adult children move in is the stuff of nightmares. Especially when you think of cramming two or more people into the space you already occupy, there's typically no way for everyone to feel comfortable. Even a short visit from friends or relatives leaves you itching for your own space again.

Fortunately, there's a real estate solution for that.

The concept of a separate space for individuals to live in semi-privacy isn't new, but the options homebuyers have to accommodate family that may visit frequently or live full time are growing -- whether you call it an in-law suite, guest house or attached apartment.

[See: 8 Potential Headaches to Be Aware of Before Becoming a Homeowner.]

The Pew Research Center reported last year that a record number of people in the U.S. -- 60.6 million people, or 19 percent of the population -- live with two or more adult generations under one roof, as of 2014, based on U.S. Census Bureau data.

The number of multigenerational households has been growing since 1980, according to Pew. But before this long-term upward trend, the number was going in the other direction. Between 1950 and 1980, the share of the population living in a multigenerational household dropped from 21 percent to 12 percent.

Traditionally, the idea of living as an adult with your parents or grandparents has been attributed to cultural norms that originate outside the U.S. -- particularly in Asian and Hispanic populations, according to the study's results -- where parents move in with their adult children upon retirement, the birth of grandchildren or a decrease in mobility.

But it's not just racial or ethnic minorities bringing U.S. families together. Multigenerational living got a boost from the Great Recession -- reaching 17 percent of the population in 2009, according to Pew -- as people struggled to afford housing and foreclosures forced extended families under one roof. The U.S. populations identifying as Asian, black, Hispanic and white all saw increases in multigenerational living between 2009 and 2014, according to Pew.

Whether it's to pool funds from more than one working generation or better care for those who aren't working, many people are seeing multigenerational housing as a smart move. Even if your parents don't live with you quite yet -- or you're not sure you'll want them to -- taking advantage of the growing list of options for multigenerational housing might be the perfect investment down the line.

More Availability

As the growing share of U.S. residents living in multigenerational households reveals, demand for housing options for expanded family units is on the rise as well.

Luxury home builder Toll Brothers, for example, has long been in the business of constructing semi-custom homes for buyers, offering a variety of layouts and designs, with the ability to tailor the home to meet the needs of the people who will be living there. Tim Gehman, director of design for Toll Brothers, says multigenerational housing has always been possible with their business model, but it has garnered more focus from homebuyers in recent years.

"You could always get additional bedrooms in a house, you could get additional suites ... but as we started to see the demand rise for a specific type of suite, we did create standard ways of doing that within many of our most popular homes," Gehman says.

He notes that Toll Brothers receives requests for multigenerational home builds from all over the U.S., though he finds they're less common on the West Coast -- likely because guest bedrooms on the ground floor are part of a traditional floor plan in the region -- and most common on the East Coast.

If you're considering bringing more family members under one roof in the next few years -- and especially if you're having your home custom built -- it may be worth considering a suite with its own entrance, so those additional adults have more independence while also remaining close by.

[Read: What Best Places to Live Are Ideal for First-Time Homebuyers?]

Ultimate Guest Space

In the years prior to your parents or in-laws moving into the additional living space, feel free to design and decorate it to your current needs -- whether that's a secluded home office, gathering area for entertaining or even the perfect place for visitors to stay the night.

The guest suite concept even translates to luxury condo communities and high-rises. At Privé at Island Estates in Aventura, Florida, buyers are able to add a separate guest suite onto their apartment home purchase. These guest suites offer ocean views and have a kitchenette, not to mention privacy for both the owner and visitor.

"We've done it before in some of our luxury buildings, and these things are just very, very popular. We can't make enough of them," says Michael Neumann, director of sales for Privé.

However, in the case of ultra-luxury like Privé, guest suites don't typically get purchased for full-time use by relatives. "We've had them in the building where the purchaser is going to also have the in-laws coming, but they buy them an apartment -- they don't buy them the guest suite," Neumann says.

Income Opportunity

If extra living space has you seeing dollar signs, there is the possibility of transforming the area into an income property by renting it out to long-term tenants, or even listing it on short-term rental sites like Airbnb and VRBO.

However, to the disappointment of many Airbnb hosts, you'll need to carefully examine zoning laws for your property and your homeowners association if you live under one. Receiving income from your property in any way could transform your property into a business, and if you're zoned as strictly residential, renting out the space is likely prohibited.

"It'll depend on zoning laws and what they're allowed to do, because a guest suite on a home would actually mean there's a separate kitchen -- it's a separate entity in itself," Neumann says.

As Neumann notes, kitchen appliances can mean the difference between a guest suite and a separate home for another household that may violate residential zoning. As a result, many in-law or guest suites are outfitted with kitchenettes rather than full kitchens.

"If there would be a permanent wired gas or electric stove, that would probably be a no-no in many municipalities," says Kira Sterling, chief marketing officer at Toll Brothers.

[Read: What Would Airbnb's Expansion to Long-Term Rentals Mean for Renters?]

Expanding Your Definition of Your Household

The wide definition of multigenerational housing and the ever-growing home models and concepts offered means the unexpected circumstances that bring everyone under one roof don't have to make things uncomfortable. Your kids moving home after college doesn't mean you can't enjoy the life of an empty nester, even with a recent grad on the couch, and needing to care for your aging parents doesn't require suffering in cramped quarters.

In homes built in active adult communities, Gehman says he's seeing more and more requests for customization with two master suites -- one on the first floor and one on the second -- to allow for two generations of aging adults.

"We've actually seen some uptick in requests for an additional master suite on the second floor for that couple that's just tipped over the 55-plus range, but they're bringing their parents in," Gehman says. "And the parents will live on the first floor, and they'll live on the second floor until they can't anymore."

Regardless of whether you're already living in a multigenerational household or if you haven't quite decided if it fits your lifestyle, the growth of availability in multigenerational housing is something to consider for future guests, potential income or simply resale value in future years.