Zoning & Size Limits
| Requirement | Mesa, AZ | Gilbert, AZ |
|---|
| Allowed Zones | All districts where a single residence is allowed (Agricultu | All single-family zoning districts (Gilbert Development Serv |
| Max Size (Detached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less | 75% of the primary residence's gross square footage (state law guarantees at least the lesser of 1,000 sq ft or 75%) |
| Max Size (Attached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less | 75% of the primary residence's gross square footage (state law guarantees at least the lesser of 1,000 sq ft or 75%) |
| Max Height | Same as primary residence height limit for the und | Same as the underlying zoning district standard fo |
| Parking Required | No additional parking required; garage/carport conversions n | No additional parking may be required (ARS 9-461.18) |
| Owner Occupancy | Not required | Not required for long-term rentals; no familial or pre-exist |
Setback Requirements
| Setback | Mesa, AZ | Gilbert, AZ |
|---|
| Rear Setback | 5 feet minimum for new structures; existing-structure conversions require no additional setback | 5 feet maximum required (ARS 9-461.18 caps rear setbacks at 5 ft) |
| Side Setback | 5 feet minimum for new structures | 5 feet maximum required (ARS 9-461.18 caps side setbacks at 5 ft) |
| Front Setback | Same as primary residence front and street-side se | Per underlying zoning district — Confirm with Gilb |
Permits & Timeline
| Detail | Mesa, AZ | Gilbert, 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 | Confirm with Gilbert Development Services (480-503-6700) |
| Permit Fees | Valuation-based per Mesa's Schedule of Fees & Charges; no flat ADU fee published — confirm with Mesa Development Services | Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services |
| Impact Fees | Development impact fees apply per Mesa City Code Title 5, Ch | System development fees apply to new dwelling units — Confir |
| Pre-Approved Plans | No city pre-approved ADU plan program identified a | No pre-approved plan library — Confirm with Gilber |
Construction Costs
| Cost | Mesa, AZ | Gilbert, AZ |
|---|
| Avg Build Cost | $120,000-$240,000 | $130,000-$260,000 |
| Cost Per Sq Ft | $135-$270 | $150-$280 |
| Garage Conversion | $60,000-$140,000 | $60,000-$140,000 |
| Prefab ADU | $85,000-$200,000 | $90,000-$210,000 |
Rental Income Potential
| Rental | Mesa, AZ | Gilbert, AZ |
|---|
| 1BR Avg Rent | $1,150-$1,450/mo | $1,500-$1,750/mo |
| 2BR Avg Rent | $1,400-$1,800/mo | $1,850-$2,300/mo |
| Short-Term Rentals | Ordinance 5883 does not address short-term rental of ADUs; A | Arizona law allows STRs with registration; ADU-specific STR |
| Est. ROI | 6-9% annual return | 6-9% annual return |
Which City Is Better for ADUs?
Mesa scores 7/10 while Gilbert 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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