Pima County, AZ Accessory Structures: ADU Rules (2026)

Accessory dwelling units are permitted on any residential or rural lot which allows a single-family dwelling.

2.   Permitted coverage: Accessory dwelling unit square footage counts toward the accessory structure lot coverage limits for the zone in which the accessory dwelling unit is located and are permitted up to the maximum allowed by Section 18.09.020.U.5. Accessory dwelling unit(s) are not restricted by the accessory structure coverage but count toward the lot coverage limits.

3.   One attached accessory dwelling unit and one detached accessory dwelling unit per lot is allowed.

4.   On lots or parcels one acre or greater in size: an additional detached dwelling unit is allowed. The third unit must be restricted affordable.

5.   Size:

a.   Detached and attached accessory dwelling unit(s) may be developed up to seventy-five percent of the gross floor area of the main dwelling or one thousand two hundred fifty square feet, whichever is less.

6.   Minimum yard setback requirements:

a.   Front: In accordance with accessory building standards of the appropriate zone.

b.   Side and Rear: five feet.

c.   Minimum distance to main structures:

i.   Lots one acre and greater: ten feet.

ii.   Lots less than one acre: three feet.

7.   Height: In accordance with single-family dwelling standards of the appropriate zone.