For Diana Limongi, the practical benefits of sharing a two-family house in Astoria, N.Y., with her parents are manifest. There is access to a car without having to own one, free Spanish immersion for her two children and periodic gifts of homemade lentils left in the refrigerator.

But the best part, the stay-at-home mother says, is when she leaves the house. “I hear my mom talking to my daughter and cracking up. It’s just pure joy, and it’s a beautiful sound. They’re really enjoying each others’ company.”

Multigenerational households — homes where two or more adult generations live together, or those that include both grandparents and grandchildren — are on the rise across the country. A record 64 million Americans live in a multigenerational home, according to a Pew Research Center report, up from 32.2 million in 1950.

There are multiple reasons: the increasing cost of long-term care; the growing immigrant population, in which shared housing has always been more common; and, of course, rising housing prices. Lawrence Yun, chief economist at the National Association of Realtors, said multifamily home purchases are especially prevalent now “because home prices are so expensive that the only way to make it work is to double up or triple up.”

John Burns, a California real estate investment consultant, said he expected the multifamily shopping trend to continue, particularly for anyone born during the 1970s, which he calls “the foreclosure generation.” People in “that group had the highest homeownership ever at their 10th reunion, then the lowest by their 20th,” he said.

And as their parents reach their 70s and 80s and need help, he said, “you’re seeing those groups pair up in all sorts of ways.”

Finding the right property to meet the needs of multiple generations is an intimidating process, but it can be done — with patience, research, preparation and some luck. For those considering it, here are some lessons from families in which multiple generations live happily together.

Before you look

Be realistic not only about how harmoniously you and your family could live together but also about how happily you could all buy a house together — a stressful endeavor even under the best circumstances. It could mean having some difficult conversations early on and setting ground rules.

Create a list of property requirements and be clear on what are absolute must-haves. While looking for a house in Astoria, where she grew up, Limongi, 36, kept in mind her husband’s desire for a yard and her father’s wish for a driveway.

“I had this checklist and was like, ‘We’re never going to find a house like this,’” she said. But they persevered, and in 2011 they found a house, built around 1920, that met their needs.

Limongi was grateful she stuck with the list. “If we had settled for a house that didn’t check all those boxes for both sides, we wouldn’t have been as happy,” she said. “One side would have always felt like they didn’t get what they wanted.”

While house hunting in the Boston area, Melisa Kenslea, her husband and her mother drew up what they called the “house prenup,” a document that addressed how the family would pay for the home and how they would cover expenses. It also included an “exit strategy,” should somebody decide to move out.

“Having that has made everything else much less stressful,” said Kenslea, 33. “We have a document to refer to: ‘This is what we all agreed on: We all signed it.’”

On the hunt

Once you have decided where you will be looking for a home, it is important to find a broker who knows the area well and is familiar with the multifamily market. Bear in mind that if the older generation is moving from a longtime family home to a new community, their concerns should be carefully weighed when considering what type of home to buy.

Some house hunters described the in-law suites in homes they saw as no more than an afterthought, which is why Jessica Peterson and her family would start with the in-law suite during showings while preparing to move her parents from Virginia to Connecticut. “We knew that if that didn’t fit with what my mom and dad were looking for, it didn’t matter if the rest of the house was beautiful,” she said.

Finding the right agent can help smooth the process. Karen K.H. Park, for example, specializes in selling multimillion-dollar homes to Chinese and Korean families in the Fort Lee, N.J., area. Park, who is Korean-American, said she can commiserate with Asian parents whose children have brought them to the country. “I understand their culture,” she said. Also, “Korean is my mother tongue. I can fully support the family.”

Immigrant families, said Yun of the National Association of Realtors, account for part of the recent boom in the multifamily market, particularly on the West Coast. “There is a larger percentage of Asian and Hispanic families in the region,” he said, “and they are culturally more accustomed to multigenerational living.”

Park said many of her younger clients prefer a property that is move-in ready, but that is not always realistic when looking for something as specific as a home that suits multiple generations.

Before you sign anything

Depending on the area, multifamily homes can come with tricky regulations on zoning, insurance and taxes. So in addition to finding a contractor to make necessary renovations, it’s a good idea to find a lawyer who can help you figure out any potential zoning issues.

When Drew Zandonella- Stannard and her husband, Jacob Conklin, built a cottage in their backyard in Seattle so her parents could live on their property, parking regulations required them to cut the curb and make space for parking in the back. And Peterson, in Connecticut, discovered she would not be allowed to rent her mother’s side of the house should she leave.

Christa Battaglia said her father asked a tax lawyer to advise them before they bought a two-family house in Chicago. She and her husband discussed buying the home and renting part of it to her father, but they couldn’t afford the mortgage on their own, and her father would have had to pay taxes on any money he gave them to help them with the purchase.

Ultimately, “it was decided that we should just own the property together,” she said. Her father took the money from his house sale and applied it directly to the purchase of the new house.

For the long haul

Anne Luce of Evanston, Ill., suggested creating two-year, five-year and 10-year plans. For example, “What if your family adds another child?” she said. She and her husband had another child while living in a two-family house with her in-laws and young son.

Or, “What if one of the older generation ends up requiring significant care?” she said.

She and her husband know that her in-laws have planned well for themselves financially and that there is room in the budget to hire help if needed. “They’ve been really open with us about that, which is reassuring,” she said.

Making sure all parties feel comfortable in their own space can take some doing. Peterson said she was surprised to learn that her parents didn’t feel like full partners. “I always thought of it as it being their side, their property. If they wanted to paint it hot pink, they could, but they didn’t feel like they owned anything.”

It helped to talk it out. “I said, ‘Mom, this is your house. I want you to be comfortable. I appreciate you asking me if you want to rip out a wall, but it’s your house.”

Ground rules

Multigenerational housing can make sense in many ways: Older parents can be near their adult children in the event of health issues or emergencies, and when there are young grandchildren, having another set of adults around can make child-rearing easier. But a number of things should be sorted out before deciding to share a home:

>> Deal-breakers: Have everyone list their must-have items and create a list that you can stick to during house hunting. Jessica Peterson was glad she and her parents got everything they wanted in their multifamily home in Connecticut. “The last thing I wanted was to push my parents into a place where they were going to be constantly complaining about how they didn’t want to live here,” she said.

>> Finances: Consider who will pay for what, and how everything will get paid. If aging parents still work, how will they deal with expenses after retirement? In addition to the home purchase, don’t forget to factor in other costs, including property taxes, renovations, monthly expenses like utilities, cable and internet service, and exterior tasks like gardening and landscaping.

>> Maintenance: Who will manage the maintenance of the house — not just landscaping, but things like cleaning the windows and gutters?

>> Caregiving: What role will grandparents play in the lives of their grandchildren? Will they be regular baby sitters? And if an aging parent requires care, how much responsibility will fall on the adult child living in the house? Are there other adult children who need to be consulted?

>> Exit strategy: If a family member moves out (or on), what will be done with the unused space? Who will receive what portion of the sale?

>> Other family members: What will happen to the other spouse’s aging parents if they need care? If adult children have siblings who do not share ownership of the house, how will their inheritance be settled?