Spokane allows ADUs in residential zones with reasonable regulations. The city is moderately ADU-friendly, with straightforward permitting and moderate size limits that accommodate most development goals.
Zoning & Size Requirements
| Allowed Zones | Single-family residential |
| Max Size (Detached) | 1,000 sq ft |
| Max Size (Attached) | 800 sq ft |
| Max Size (JADU) | Not allowed |
| Max Height | 35 feet |
| Max Units | 1 ADU per lot |
Setback Requirements
| Rear Setback | 15 feet |
| Side Setback | 5 feet |
| Front Setback | 20 feet |
| Parking Required | 1 space per unit |
| Owner Occupancy | Not required |
| Min Lot Size | 5,000 sq ft |
Permit Process & Fees
| Approval Process | Standard building permit |
| Review Timeline | 50-75 days |
| Permit Fees | $2,000-$3,500 |
| Impact Fees | $600-$1,200 |
| Plan Check | 2-3 weeks |
| Pre-Approved Plans | Limited availability |
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Construction Costs
| Average Build Cost | $110,000-$220,000 |
| Cost per Sq Ft | $110-$220 |
| Garage Conversion | $50,000-$120,000 |
| Prefab ADU (Installed) | $80,000-$180,000 (installed) |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders in minutes.
Compare ADU Financing Options →Rental Income Potential
| Avg Rent (1 Bedroom) | $1,000-$1,450/mo |
| Avg Rent (2 Bedroom) | $1,300-$1,900/mo |
| Short-Term Rental | Not permitted |
| Est. Annual ROI | 8-12% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half. Compare top prefab manufacturers.
Compare Prefab ADUs →Recent Law Changes
What's Changed Recently
- 2024: Increased max detached ADU size from 900 to 1,000 sq ft
- 2023: Streamlined permitting timeline
- 2024: Expanded ADU allowance in infill zones
- 2023: Reduced parking requirements for corner lots
Tips for Building an ADU in Spokane
- Spokane's lower property costs mean excellent cash flow on ADU rentals
- Long-term rental market is stable and strong
- More conservative approach than western Washington cities; straightforward rules
- Highest ROI of Washington cities due to lower construction and land costs
Frequently Asked Questions
Can I build an ADU in Spokane?
Yes. ADUs are allowed in Single-family residential in Spokane. The maximum size for a detached ADU is 1,000 sq ft. No owner-occupancy is required.
How much does an ADU cost in Spokane?
ADU construction in Spokane typically costs $110,000-$220,000. Garage conversions run $50,000-$120,000, and prefab ADUs cost $80,000-$180,000 (installed).
How much can I rent an ADU for in Spokane?
Average ADU rents in Spokane are $1,000-$1,450/mo for a 1-bedroom and $1,300-$1,900/mo for a 2-bedroom unit.
Do I need parking for an ADU in Spokane?
1 space per unit. Check with Spokane planning department for the latest Washington ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Spokane?
The permit review timeline in Spokane is 50-75 days. Fees range from $2,000-$3,500.
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