Apex, N.C. — Whether it's taking in aging parents or adult children moving back home, many families find themselves doubling up under one roof. A new housing design in the Triangle is allowing families a place to live together with space and comfort.

Lennar Corporation has created “NextGen spaces,” which are described as a home within a home. It is the first builder to introduce the dual-home concept to the Triangle. Lennar is offering the floor plan in Bella Casa in Apex and at Flowers Plantation in Clayton. It will be available in communities in Cary and Wake Forest next year.

They look like any other single-family home – a very roomy home, at 3,700-square-feet – but two entry doors lead to two distinct living spaces, which are connected by an internal door.

“You have a living room in this space. You have a living room in the other space. You have a laundry room within this space. You have a laundry room in the other space,” said Allison Stewart-Smull, director of sales for Lennar.

A record 51 million Americans are living in a home with at least two adult generations, driven by job losses and home foreclosures, and builders say they expect that number to grow.

In the Triangle region, nearly 30 percent of residents older than 65 live alone, according to the state Division of Aging and Adult Services – a clear signal of demand for multi-generational homes, according to housing researchers.

“We’ve seen families looking for this,” Stewart-Smull said. “If you have a parent who’s not quite ready for say, in an assisted living situation, but you need to check on them occasionally and make sure they’re doing OK, they’re right here and very convenient to do. But then, if you want to go three days and not talk at all, that’s possible, too.”

The space works not just for aging parents, but also grown kids who've had to move back in with mom and dad. One model of the home goes for $414,000. The floor plan starts at $360,000.