Zoning & Size Limits
| Requirement | Portland, OR | Beaverton, OR |
|---|
| Allowed Zones | All residential zones | Any zoning district that allows a single-detached dwelling a |
| Max Size (Detached) | 800 sq ft or 75% of primary (whichever is less) | 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less |
| Max Size (Attached) | 800 sq ft or 75% of primary living area (same cap as detached; no separate 1,000 sq ft limit) | 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less |
| Max Height | 20 ft (outside setbacks); 15 ft (within setbacks) | Per the underlying zone's accessory-structure/dwel |
| Parking Required | Optional | No additional off-street parking may be required (ORS 197.31 |
| Owner Occupancy | Not required | Not required — Oregon law prohibits owner-occupancy conditio |
Setback Requirements
| Setback | Portland, OR | Beaverton, OR |
|---|
| Rear Setback | 5 feet | Per underlying zone accessory-structure standards — Confirm with Beaverton Planning Division |
| Side Setback | 0 feet with easement | Per underlying zone accessory-structure standards — Confirm with Beaverton Planning Division |
| Front Setback | 0 feet (alley lot) | Per underlying zone — Confirm with Beaverton Plann |
Permits & Timeline
| Detail | Portland, OR | Beaverton, OR |
|---|
| Permit Timeline | 30-45 days | Commonly 2-4 months total from application to permit issuance — Confirm with Beaverton Planning Division |
| Permit Fees | ~$1,900 permit and plan review; plus System Development Charges (SDCs) of about $19,000 - see impact fees | Type 1 application fee plus valuation-based building permit fees (third-party guides estimate $2,500-$9,000) — Confirm with Beaverton Building Division |
| Impact Fees | SDCs total roughly $18,900 for a detached ADU (Parks ~$7,100 | System Development Charges (city, Washington County TDT, Cle |
| Pre-Approved Plans | Extensive pre-approved library available | No city pre-approved plan library — Confirm with B |
Construction Costs
| Cost | Portland, OR | Beaverton, OR |
|---|
| Avg Build Cost | $150,000-$300,000 | $150,000-$320,000 |
| Cost Per Sq Ft | $125-$250 | $150-$300 |
| Garage Conversion | $70,000-$160,000 | $100,000-$180,000 |
| Prefab ADU | $100,000-$240,000 | $100,000-$240,000 |
Rental Income Potential
| Rental | Portland, OR | Beaverton, OR |
|---|
| 1BR Avg Rent | $1,400-$1,900/mo | $1,400-$1,700/mo |
| 2BR Avg Rent | $1,800-$2,600/mo | $1,700-$2,000/mo |
| Short-Term Rentals | Yes, with registration | No statewide ban; check Beaverton business-license and any S |
| Est. ROI | 6-9% annual return | 6-8% annual return |
Which City Is Better for ADUs?
Portland scores 9/10 while Beaverton scores 7/10 on our ADU-friendliness index.
Portland 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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