How much does a casita or ADU cost in Phoenix?

Phoenix casita and ADU pricing in 2026 reflects Arizona HB 2720 statewide ADU reform, the city's revised zoning code, and three distinct delivery scopes.

Converting an existing attached space — a garage, bonus room, or enclosed patio — into a legal Junior ADU runs $60,000 to $135,000. Per Phoenix Zoning Ordinance Section 608, JADUs up to 1,000 square feet on owner-occupied parcels qualify for streamlined ministerial review when carved from existing conditioned space. The price band covers fire separation per IRC R302.3, a kitchenette under IRC E3702 with dedicated 20A circuit, a 3/4 bath with proper vent stack tie-in per IPC 906, and a separate exterior entrance.

A detached stick-built casita 500-750 square feet with kitchenette and full bath runs $180,000 to $310,000. The price absorbs new foundation per IRC R403, full electrical service drop or sub-feed per NEC 230, dedicated water and sewer laterals or shared connection with a yard cleanout, and a separate Maricopa County Assessor parcel sub-record. HB 2720 eliminated owner-occupancy requirements and capped impact fees at one-third of the primary dwelling rate.

The high-end band — $345,000 to $525,000 — covers detached units 900-1,100 square feet with full kitchen, primary bath, laundry, and finish-quality matching the main home. Costs scale with foundation system, mini-split versus full ducted HVAC sized per Manual J, and whether the primary house electrical service requires upgrade to 200A.

Arizona HB 2720, effective January 2025, removed many municipal blockers including owner-occupancy mandates, parking minimums on lots within a half-mile of transit, and design-review committees with discretionary veto. City permits, HOA architectural review under CC&R covenants (HB 2720 does not preempt HOA rules), and SRP/APS utility tie-ins still gate timeline. Expect 8-14 weeks plan review and 4-7 months construction.