In-Laws, Outlaws, and Granny Flats: Your Guide to Turning One House Into Two HomesINLAWS, OUTLAWS AND GRANNY FLATS: Your guide to creating an ADU Homeowners are creating second dwelling units often called Accessory Dwellings, ADUs, in law suites, mother in law apartments, or granny flats. Second units make a lot of sense. They're perfect for families who want several generations living close by, they enable Baby Boomers to care for elderly parents while respecting their independence, provide private quarters for adult children