Zoning & Size Limits
| Requirement | Mesa, AZ | Phoenix, AZ |
|---|
| Allowed Zones | All districts where a single residence is allowed (Agricultu | Single-family residential zones |
| Max Size (Detached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less | 900 sq ft |
| Max Size (Attached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less | 75% of primary dwelling, capped at 1,000 sq ft (lots ≤10,000 sq ft) |
| Max Height | Same as primary residence height limit for the und | 15 ft (use permit may allow more) |
| Parking Required | No additional parking required; garage/carport conversions n | No additional parking required (AZ HB 2720, effective Jan 20 |
| Owner Occupancy | Not required | Not required |
Setback Requirements
| Setback | Mesa, AZ | Phoenix, AZ |
|---|
| Rear Setback | 5 feet minimum for new structures; existing-structure conversions require no additional setback | 15 feet |
| Side Setback | 5 feet minimum for new structures | 5 feet |
| Front Setback | Same as primary residence front and street-side se | 25 feet |
Permits & Timeline
| Detail | Mesa, AZ | Phoenix, AZ |
|---|
| Permit Timeline | Residential plan review commonly runs days-to-weeks per third-party permit data (3-18 business days cited); confirm current turnaround on Mesa's Building Permits Dashboard | 60-90 days |
| Permit Fees | Valuation-based per Mesa's Schedule of Fees & Charges; no flat ADU fee published — confirm with Mesa Development Services | $2,500-$4,200 |
| Impact Fees | Development impact fees apply per Mesa City Code Title 5, Ch | $900-$1,600 |
| Pre-Approved Plans | No city pre-approved ADU plan program identified a | Limited availability |
Construction Costs
| Cost | Mesa, AZ | Phoenix, AZ |
|---|
| Avg Build Cost | $120,000-$240,000 | $120,000-$240,000 |
| Cost Per Sq Ft | $135-$270 | $135-$270 |
| Garage Conversion | $60,000-$140,000 | $60,000-$140,000 |
| Prefab ADU | $85,000-$200,000 | $85,000-$200,000 |
Rental Income Potential
| Rental | Mesa, AZ | Phoenix, AZ |
|---|
| 1BR Avg Rent | $1,150-$1,450/mo | $1,250-$1,700/mo |
| 2BR Avg Rent | $1,400-$1,800/mo | $1,600-$2,200/mo |
| Short-Term Rentals | Ordinance 5883 does not address short-term rental of ADUs; A | Varies by neighborhood |
| Est. ROI | 6-9% annual return | 7-10% annual return |
Which City Is Better for ADUs?
Mesa scores 7/10 while Phoenix scores 6/10 on our ADU-friendliness index.
Mesa 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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