Can I add an accessory dwelling unit (ADU) or casita in Surprise?

Yes. Surprise's adopted Accessory Dwelling Unit standard (LDO Chapter 106, Article XI, Sec. 106-11.1 through Sec. 106-11.7, adopted by Ord. No. 2025-43 effective 12-17-24) matches Arizona's statewide by-right ADU law (HB2720, 2024, A.R.S. Sec. 9-461.18), which applies to Surprise because its population is well above the law's 75,000-resident threshold (143,148 at the 2020 census). On a qualifying single-family lot, up to 1 attached and 1 detached ADU are a permitted use (up to 1 attached and 2 detached on lots of 1 acre or more if at least one ADU is deed-restricted affordable). An ADU cannot exceed the lesser of 75 percent of the primary home's gross floor area or 1,000 square feet. It follows the same setbacks, lot coverage, and height as the primary home, except the rear and side setbacks drop to a minimum of 5 feet, no extra parking is required, and the ADU's exterior does not have to match the primary home. ADUs are not allowed alongside a duplex or other multifamily use on the same lot, or on tribal land or near a military or public airport. Confirm your specific lot's eligibility and the permit process with Community Development, Planning and Zoning (623-222-3000). This pack covers incorporated Surprise only; unincorporated Maricopa County land uses county zoning.