Zoning & Size Limits
| Requirement | Phoenix, AZ | Scottsdale, AZ |
|---|
| Allowed Zones | Single-family residential zones | Very limited residential zones |
| Max Size (Detached) | 1,000 sq ft on lots up to 10,000 sq ft (75% of primary dwelling, whichever is less); on lots over 10,000 sq ft, the lesser of 3,000 sq ft or 10% of net lot area | 1,000 sq ft or 75% of primary dwelling (whichever is less); 500 sq ft for second/third ADU |
| Max Size (Attached) | 75% of primary dwelling, capped at 1,000 sq ft (lots ≤10,000 sq ft) | 1,000 sq ft or 75% of primary dwelling (whichever is less) |
| Max Height | 15 ft when within required rear/side yards (greate | Per underlying zoning district (no ADU-specific he |
| Parking Required | No additional parking required (ARS 9-461.18 / AZ HB 2720 pr | No additional parking required for the ADU (existing parking |
| Owner Occupancy | Not required for long-term rental; owner must reside on-site | Not required for long-term rental; owner must reside on-site |
Setback Requirements
| Setback | Phoenix, AZ | Scottsdale, AZ |
|---|
| Rear Setback | 5 feet (3 ft for some detached configurations per ZO 706; statute caps rear/side at 5 ft) | 5 feet (detached ADU may be as close as 5 ft to rear lot line) |
| Side Setback | 5 feet (3 ft for some detached configurations per ZO 706) | 5 feet (detached ADU may be as close as 5 ft to side lot line; may not be in required front yard) |
| Front Setback | Per underlying zoning district (no ADU-specific fr | Per zone (detached ADU may not be built in a requi |
Permits & Timeline
| Detail | Phoenix, AZ | Scottsdale, AZ |
|---|
| Permit Timeline | 60-90 days | 120-180 days |
| Permit Fees | $2,500-$4,200 | $5,000-$8,000 |
| Impact Fees | $900-$1,600 | $2,000-$3,000 |
| Pre-Approved Plans | Limited availability | Not available |
Construction Costs
| Cost | Phoenix, AZ | Scottsdale, AZ |
|---|
| Avg Build Cost | $120,000-$240,000 | $140,000-$280,000 |
| Cost Per Sq Ft | $135-$270 | $200-$400 |
| Garage Conversion | $60,000-$140,000 | $75,000-$170,000 |
| Prefab ADU | $85,000-$200,000 | $110,000-$240,000 |
Rental Income Potential
| Rental | Phoenix, AZ | Scottsdale, AZ |
|---|
| 1BR Avg Rent | $1,250-$1,700/mo | $1,500-$2,000/mo |
| 2BR Avg Rent | $1,600-$2,200/mo | $1,900-$2,600/mo |
| Short-Term Rentals | Varies by neighborhood | Not permitted |
| Est. ROI | 7-10% annual return | 4-6% annual return |
Which City Is Better for ADUs?
Phoenix scores 6/10 while Scottsdale scores 5/10 on our ADU-friendliness index.
Phoenix edges ahead overall. Both cities offer viable ADU development opportunities — the best choice depends on your specific property, budget, and goals.
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