While millennials are commonly reported to be moving in with their parents, another group of people have been quietly doubling up: baby boomers and their own aging parents, according to an article in MarketWatch.

The article explained that this trend is not likely to change anytime soon even with an improving economy, as people live longer and require more care at the end of their lives.

A recent survey by the American Institute of Architects found that dedicated guest rooms, including in-law suites (that can be as simple as a secondary master bedroom suite with a bathroom), have been gaining in popularity over the past couple of years. In 2014, 39% of respondents in a group of more than 500 residential architecture firms said they were seeing more demand for this feature, compared with 26% who said the same in 2013 and 10% in 2012. Also getting hotter: Home features that accommodate multiple generations and age-in-place features.

“As many households become caretakers for aging relatives, separate living suites have become popular options for accommodations,” said Kermit Baker, chief economist for AIA, in a news release.