Forty-five years ago, Betty Szudy and her wife, Maggie Roth, both 70, bought a Craftsman bungalow in Oakland, Calif. In 2017, at the same time their son and his wife were fruitlessly searching for an affordable apartment in the neighborhood, California was liberalizing its housing laws to encourage so-called accessory dwelling units, or A.D.U.s.
So, the family looked into building one. The parents now live in the main house and the adult children in the A.D.U. — in this case, a once-decrepit garage transformed into a 400-square-foot studio with a kitchen and bath. The arrangement makes it simple to share meals, planned or spontaneous, and to pick up items for the other household at Trader Joe’s. “I love having them around,” Ms. Szudy said.