Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Beaverton ADU cost →Building an ADU in Beaverton costs between $150,000-$320,000 for new construction, with per-square-foot costs averaging $150-$300. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $100,000-$180,000, while prefab/modular ADUs fall in between at $100,000-$240,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & 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 | System Development Charges (city, Washington County TDT, Clean Water Services) apply and can add five figures — Confirm current SDC schedule with Beaverton Site Development |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. Get up to 3 free quotes from ADU builders serving Beaverton — no obligation.
Get Beaverton builder quotes →Permit fees in Beaverton are Type 1 application fee plus valuation-based building permit fees (third-party guides estimate $2,500-$9,000) — Confirm with Beaverton Building Division. The review timeline is Commonly 2-4 months total from application to permit issuance — Confirm with Beaverton Planning Division, with plan check: Included in building permit review — Confirm with Beaverton Building Division. Impact fees are System Development Charges (city, Washington County TDT, Clean Water Services) apply and can add five figures — Confirm current SDC schedule with Beaverton Site Development. Pre-approved plans: No city pre-approved plan library — Confirm with Beaverton Planning Division.
| 1-Bedroom Rent | $1,400-$1,700/month |
| 2-Bedroom Rent | $1,700-$2,000/month |
| Annual Rental Income (est.) | $18,600/year |
| Payback Period (est.) | 12.6 years |
| Short-Term Rental | No statewide ban; check Beaverton business-license and any STR requirements — Confirm with the City of Beaverton |
| Overall ROI Estimate | 6-8% annual return |
A typical ADU in Beaverton generates approximately $18,600 per year in rental income based on average 1-bedroom rents. At an average construction cost of $235,000, the estimated payback period is 12.6 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Beaverton and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Beaverton: $100,000-$180,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $100,000-$240,000.
3. Pre-approved plans — Beaverton does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000).
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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