Tucson’s current Unified Development Code sets different accessory dwelling unit (ADU) counts for a Family Dwelling and a duplex. Read current UDC §6.6.3 rather than relying on older City FAQ text that predates later amendments.
Count units by the parcel’s existing dwelling type
The current code allows two ADUs on a parcel developed with a qualifying Family Dwelling, except a Multifamily Development. A parcel developed with a duplex is allowed one ADU. The code also allows one further ADU on a lot larger than one acre when at least one ADU is a restricted affordable dwelling unit and the required deed restriction is provided as a building-permit condition.
Before applying these counts, confirm that the parcel is within Tucson, identify the existing dwelling classification, and check the current zone and overlay. The code’s use of “Family Dwelling” and “Multifamily Development” matters; a parcel’s mailing address or informal label does not settle which branch applies.
Keep other standards in view
The code says ADUs do not count toward maximum residential density and do not require vehicle parking, while retaining applicable dimensional and overlay standards. It also sets ADU-specific size and yard rules. Those details can change whether a counted unit fits the site, but a unit count alone is not a site approval.
The City’s public materials include historical ADU summaries, so use the live code and current City confirmation for the parcel. This screen does not replace building permits or a review of project-specific conditions.