Zoning & Size Limits
| Requirement | Tempe, AZ | Phoenix, AZ |
|---|
| Allowed Zones | All single-family residential districts citywide (per ARS 9- | Single-family residential zones |
| Max Size (Detached) | 1,000 sq ft or 75% of the main dwelling's gross floor area, whichever is less | 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 |
| Max Size (Attached) | 1,000 sq ft or 75% of the main dwelling's gross floor area, whichever is less | 75% of primary dwelling, capped at 1,000 sq ft (lots ≤10,000 sq ft) |
| Max Height | Same as the underlying zoning district standard (t | 15 ft when within required rear/side yards (greate |
| Parking Required | No additional parking may be required (ARS 9-461.18 bars ADU | No additional parking required (ARS 9-461.18 / AZ HB 2720 pr |
| Owner Occupancy | Not required for long-term rentals; owner must reside on sit | Not required for long-term rental; owner must reside on-site |
Setback Requirements
| Setback | Tempe, AZ | Phoenix, AZ |
|---|
| Rear Setback | 5 feet minimum (all districts, unless the district allows less) | 5 feet (3 ft for some detached configurations per ZO 706; statute caps rear/side at 5 ft) |
| Side Setback | 5 feet minimum, including street side yards (all districts, unless the district allows less) | 5 feet (3 ft for some detached configurations per ZO 706) |
| Front Setback | Per underlying zoning district — Confirm with Temp | Per underlying zoning district (no ADU-specific fr |
Permits & Timeline
| Detail | Tempe, AZ | Phoenix, AZ |
|---|
| Permit Timeline | Typically 4-8 weeks for residential plan review — Confirm with Tempe Community Development | 60-90 days |
| Permit Fees | Building permit and plan review fees based on valuation — Confirm with Tempe Community Development | $2,500-$4,200 |
| Impact Fees | Confirm with Tempe Community Development; state law bars ADU | $900-$1,600 |
| Pre-Approved Plans | No city pre-approved plan library — Confirm with T | Limited availability |
Construction Costs
| Cost | Tempe, AZ | Phoenix, AZ |
|---|
| Avg Build Cost | $120,000-$250,000 | $120,000-$240,000 |
| Cost Per Sq Ft | $140-$280 | $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 | Tempe, AZ | Phoenix, AZ |
|---|
| 1BR Avg Rent | $1,300-$1,700/mo | $1,250-$1,700/mo |
| 2BR Avg Rent | $1,600-$2,100/mo | $1,600-$2,200/mo |
| Short-Term Rentals | Allowed with an Arizona/Tempe STR license, but the owner mus | Varies by neighborhood |
| Est. ROI | 7-10% annual return | 7-10% annual return |
Which City Is Better for ADUs?
Tempe scores 7/10 while Phoenix scores 6/10 on our ADU-friendliness index.
Tempe 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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