"Once known as a granny flat or in-law suite, such backyard apartments now go by a more formal, and formidable, name: Accessory Dwelling Unit, or ADU. Although the form has been on the books in Philadelphia since 2012, when the zoning code was revamped, not a single ADU has been built to date, according to Paul Chrystie, a city spokesperson.
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She noted that Portland, Ore., which was an early and enthusiastic supporter of ADUs, has produced very few granny flats so far. Los Angeles, which faces a dire housing shortage, has only just started to see the numbers rise. One of the big challenges, Morris said, is that most lenders don’t have a way to approve mortgages for ADUs, forcing homeowners to finance them with cash or a home equity loan."
https://www.inquirer.com/real-estate/inga-saffron/robert-venturi-adu-granny-flat-affordable-multigenerational-housing-20220204.html
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She noted that Portland, Ore., which was an early and enthusiastic supporter of ADUs, has produced very few granny flats so far. Los Angeles, which faces a dire housing shortage, has only just started to see the numbers rise. One of the big challenges, Morris said, is that most lenders don’t have a way to approve mortgages for ADUs, forcing homeowners to finance them with cash or a home equity loan."
https://www.inquirer.com/real-estate/inga-saffron/robert-venturi-adu-granny-flat-affordable-multigenerational-housing-20220204.html