Transcript for New Kind of Homes for Modern American Families
Reporter: It's the in-law apartment on steroids. The home of the future might look something like this. This. Or even this. New construction going up at record pace, built to accommodate moms and dads, their older kids and aging parents. One out of three of our homes we're selling in these communities are the next gen homes. Reporter: This family found it cost effective, with their older son and mom returning to the nest. I have the sense of independence and I have my own pla place, where I can come and go. Reporter: They are part of a growing trend. In 2010, nearly 4.5 million homes reported three or more generations living in them. A 30% increase from ten years earlier. But not everyone can afford to buy a new house. Modular additions to exist iing homes like this are putting money backe housing market. Everybody sms to be blending in and melding nicely and -- Reporter: It's all working. Yeah. Reporter: Three generations of murphies all live here under the safe room. It's just the blueprint that's changed. You couldn't even know this is not part of the original house. And check out this prebuilt room and bathroom added to the back of their house in just eight weeks, for less than half the cost of building an addition. Socorrito baes-page had the same idea for her mother viola, but she chose to have this cottage delivered straight to her backyard. She's used to having her family around her all the time. Reporter: A growing niche, helping american housing bounce back. Linsey davis, abc news, new york.
This transcript has been automatically generated and may not be 100% accurate.