Arizona’s new 2025 ADU law opens the door for homeowners—especially investors in Maricopa and Pinal Counties—to add backyard rentals, multigenerational casitas, or downsized living options. But the law comes with very specific rules you need to understand before building.
Key Points
- Cities 75,000+ must allow ADUs
Phoenix, Chandler, Tucson, Scottsdale, Mesa, and other large cities must permit ADUs on single-family lots. - Size caps
Max ADU size = the lesser of 1,000 sq ft or 75% of the main home. - Setback minimums
Side and rear setbacks limited to no more than 5 ft, opening up more buildable space on small lots. - Flexible design rules
Cities can’t require ADUs to match the main home’s exact architecture. - HOA limitations still apply
State law restricts HOAs from banning ADUs, but covenants may still limit design or placement. - Permit process still required
State law doesn’t override local building codes—permits and inspections still apply. - Rental flexibility
Owner occupancy not required. Both the primary home and ADU can be rented. - Cost considerations
Budget for permits, utilities, and potential infrastructure upgrades.
Why This Matters for Arizona Investors
- ADUs expand long-term rental income potential without buying new land.
- Reduced design restrictions make construction more feasible and cost-effective.
- Tight supply plus strong migration keeps SFR + ADU combos highly rentable.
- Legal clarity reduces risk—especially important given that 85% of landlords say PMs reduce liability (per research)