The skyrocketing cost of California’s Bay Area housing almost forced Marietta Borgel to leave San Jose, the place she’s called home for six decades. Then she discovered home-sharing and, for the first time in her 75 years, Borgel moved in with a roommate.

Life in a traditional retirement home didn’t appeal to Angela Hunkler, a 73-year-old artist, so she and her wife, Kate Murphy, sold their Berkeley house and bought a small condominium in a senior co-housing community on the waterfront in Oakland. It’s an easy walk to her studio and the views of the water just won’t quit.

Borgel and Hunkler are part of a burgeoning trend in communal living among seniors, who are banding together to share resources and camaraderie. Whether they’re finding roommates or living in a modern co-housing development — private homes clustered around shared spaces that residents manage together — these seniors are finding a new way of thinking about retirement, one that revolves around creating a community where you can age in place with others. Some say living-together options are the future of aging.

“These folks are really pioneering a new way of living,” says Anne Glass, a professor of gerontology at University of North Carolina Wilmington. “So many older people endure a crippling sense of isolation. Why not live in a village where you know all of your neighbors?”

Companionship is a key reason seniors are turning to shared housing. Loneliness is a huge health risk for older Americans, bigger than smoking or obesity according to a 2015 Brigham Young University study. The desire for independence is another factor fueling the trend.

RESIDENTS IN CHARGE

Unlike in a traditional retirement community, residents in co-housing communities are in charge. They decide how things should work. Some communities vote; others just work toward a consensus. There is no staff providing meals, landscaping or programs. The residents, most of whom sell family homes to finance their moves, volunteer to do all that.

“This isn’t an institution, it’s a community,” says Murphy, 64, an estate lawyer. “No one wants to live in an institution.”

In the Bay Area, there are three senior co-housing communities — Phoenix Commons, which opened two years ago, the Mountain View Cohousing Community and Santa Cruz’s Walnut Commons. The attraction isn’t about price: Most units aren’t much cheaper than any other Bay Area home. There are 13 other communities across the country and more are beginning to take shape, including one in Marin. The nation’s first senior co-housing community opened in 2005 at Davis’ Glacier Circle.

For those on fixed incomes who want to stay in their own homes — or are happy living in someone else’s — there is also home sharing. Organizations and even private companies are springing up to make the traditional roommate search much easier.

“It would be nice if we lived in a society with a safety net so that everyone knew they could make ends meet, but we don’t,” says Glass. “Home sharing can be a blessing for seniors who are cash-strapped.”

As baby boomers age, they are demanding alternatives to the traditional retirement home, experts say. Overall, the number of U.S. residents age 65 and over grew from 35 million in 2000 to 49.2 million in 2016, according to Census data. And there are now 4 million women over the age of 50 who live with two other women of the same age, according to AARP.

“The boomers have revolutionized every stage of life, and the senior years are no different,” says Wendi Burkhardt, CEO of Denver-based Silvernest, which is sort of like a Match.com for seniors who want to share living spaces. Launched in 2015, Silvernest has connected many Bay Area seniors. “In the past, you lived at home and then you went into assisted living. Now, people want more control over how they age.”

HAVING FUN

The vibrant lifestyle you find at Phoenix Commons, a 41-unit senior co-housing community on Oakland’s waterfront, looks a lot more like an episode of “Friends” than “The Golden Girls.” Prices range from $500,000 for the smaller units to $700,000 and up.

JoAnna Allen, 75, is a longboat racer and a carpenter who moved with her husband from the Midwest to be closer to their grandchildren. Jane Voytek, 66, who manages the donor database at Berkeley Rep, often hits the hot tub.

“My daughter says it’s like a dorm for grownups,” says Voytek, who moved in after years of living in a condo at Jack London Square where she never got to know anyone. “All you have to do is come downstairs to find friendship.”

Residents own condos that frame the community’s common spaces where people can easily socialize — a kitchen, a dining room and a gym. Like other retirement communities, there are guest units where family or caregivers can stay if needed. Phoenix Commons has a rooftop garden and a library, while the 19-unit Mountain View Cohousing Community, where units sell for $1 million and up, is built around a picturesque garden.

“It’s a lot of fun to garden with other people, while alone it can be drudgery,” says Patricia Ann Boomer, 63, who picks strawberries for breakfast at the Mountain View community, where she moved after selling her Peninsula home. “I love the feeling of a good old-fashioned neighborhood.”

A few times a week, residents break bread together, which keeps people connected.

“The common meals are the glue of the community,” says Hunkler, tucking into a meal of lasagna and apple crisp at Phoenix. “It’s when we chat and catch up.”

Of course, you can always retreat to your own private condo. At Phoenix, the code is simple: Close your blinds if you don’t want visitors.

PRIVACY TAKES A HIT

You may have to work a little harder to keep your privacy in a home-sharing arrangement.

Still, renting out a room is one way to raise extra money and avoid living alone. On the other side of arrangement, it’s a way to live in the Bay Area without having to fork out big bucks.

Sharing a home was a lifesaver for Borgel. She couldn’t find any place she could afford and having a dog made it harder.

“A lot of elderly people end up homeless in Silicon Valley and I can see why,” says Borgel. “It’s a real struggle living here on Social Security. It’s been very hard.”

Then she found Cathy Logie, 50, an empty nester with four bedrooms. They met through a mutual friend and now live together in Logie’s house with two dogs, a cat and three foster kittens.

“It’s nice to have someone around,” says Logie, a tech freelancer who lives in San Jose. “We walk the dogs together.”

Getting a roommate also has been a game changer for Joseph Karnicky. The retired engineer suffers from multiple sclerosis, which has left him almost completely paralyzed and in a wheelchair. The Menlo Park resident needed a helping hand, so he found a housemate through a home-sharing service run by HIP Housing, a San Mateo County nonprofit.

“I don’t want to leave my home,” says Karnicky, who has wired a lot of his house for voice commands. “I need my freedom.”

Disagreements happen in shared housing situations, of course. Over the years, Karnicky has had his share of horrible housemates, including one who stole from him and smoked crack.

“You need to find a good fit or it can be a nightmare,” says Karnicky.

And at Phoenix, one hot button issue is when and where to walk the dogs (There are 14 of them).

“A lot of people romanticize living in a community,” says Marianne Kilkenny, an expert on senior communities. “The reality is that we are human and there will be conflict.”

Still, having people around you can count on in a pinch can be priceless.

“There is always someone you can turn to,” says Hunkler.