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What is an ADU, Why is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary residential unit that is included on the same parcel as the primary residential unit. On the surface, it often acts the same as a duplex, however it is the outcome of a different piece of zoning regulation. Zoning is how cities determine what is allowed where, across city boundaries. Duplexes, 3-plexes, 4-plexes and beyond are permitted in various Multi-Family zones (Noted in Phoenix Zoning Code as R-X). When permitted, ADU regulation is generally included in Single-Family residential zones (Noted in Phoenix Zoning Code as R1-X) and as such, they typically have more constraints in their development and use regulations. This issue is focused specifically on ADUs as a way of increasing housing options in Phoenix, which is overwhelmingly zoned Single-Family. It is worth noting however, that there are areas of Single-Family homes in Multi-Family zones. If you are interested in building more units on 4
your property, know your zoning. It can be checked on the Maricopa county assessor website. Check your zoning here. Find what it means here. ADUs are commonly called in-law units or granny flats which points to one of their typical uses. ADUs are a great way to allow for aging in place or other multi-generational family organizations. They can also be used to earn additional income through rent. ADUs give flexibility to adapt to changing life circumstances without having to leave one neighborhood for another. They also add housing options to areas that have limited supply. The average single family home has been continually adding square footage over time. This is largely out of step with demographics that have been changing over the last few decades. ADUs are a fantastic option for demographics outside of the nuclear family that single family homes are built for.
