As Bob Dylan first sang nearly 48 years ago: "The times, they are a-changin." And it certainly holds true in the homebuilding profession, where builders are revamping product offerings to serve families with multiple generations living under one roof. A few years ago, 20-somethings, armed with a decent FICO score and a steady job, could easily qualify for a mortgage. Now we find ourselves in a world where homeownership is marred by tighter underwriting guidelines and a lack of secure employment among potential homebuyers. As the economy lingers in the doldrums, families are shacking up and housing multiple generations under one roof. Consequently, homebuilders are no longer waiting for the kids to move out. Instead, they're moving in with new ideas on how to accommodate this growing segment of the population. Lennar Corp. [stock LEN][/stock] is one an example of a homebuilder practicing innovation at a time of great change, according to John Burns, chief executive of John Burns Real Estate Consulting. Lennar is now selling what it calls a home-within-a-home. The company is offering houses that feature a full home connected to a smaller apartment. The home-within-a-home concept is designed to give families more versatility in living arrangements. For example, if grandma or grandpa move back in, the NextGen home offers them a private suite with a bedroom, living area, kitchen, bathroom and a separate patio. The living areas are separated by double doors, for example, if more privacy is desired. Prior to the baby boomers, adulthood was not defined by owning your own property. In fact, older generations stayed within the confines of the family unit they could afford mortgages of their own. At the time, this arrangement was considered a sign of prudence and fiscal conservatism since it gave older generations a place to stay and younger generations a place to live, while saving money to secure a solid future. In the post-modern age, families moved away from this design, forcing the idea of high rents and big mortgage payments on young, unsuspecting buyers. Today's economy is turning the market retro, giving builders a chance to differentiate themselves through the products that they offer. Lennar's product shows the family-model is back in-vogue. It will be interesting to see what other building innovations are spawned by the changing marketplace. Write to: Kerri Panchuk.