Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Beaverton ADU cost →Building an ADU in Beaverton costs between $165,000-$300,000 for new construction, with per-square-foot costs averaging $200-$420. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $70,000-$160,000, while prefab/modular ADUs fall in between at $100,000-$240,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | The ADU land-use fee is set in the Citywide Comprehensive Fee Schedule (Exhibit A to the fee resolution) and the building permit is valuation-based (Building Permit Fee Schedule B70-1108); both PDFs were behind a bot check on 9/20/2026, so confirm current figures with Community Development. |
| Impact Fees | System Development Charges from the city (transportation, water), Tualatin Hills Park & Recreation District, Clean Water Services (sanitary/stormwater) and Washington County (Transportation Development Tax) apply to a new dwelling unit; ADU treatment and any reductions are in the city's SDC handout B70-1116, unreachable on 9/20/2026. Ask the Site Development Division for a written SDC estimate before design. |
| 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. We pass your request to up to 5 local builders serving Beaverton, where we have them — free, no obligation.
Get Beaverton builder quotes →Permit fees in Beaverton are The ADU land-use fee is set in the Citywide Comprehensive Fee Schedule (Exhibit A to the fee resolution) and the building permit is valuation-based (Building Permit Fee Schedule B70-1108); both PDFs were behind a bot check on 9/20/2026, so confirm current figures with Community Development.. The review timeline is Not published. The Type 1 ADU decision is made by the Director without a hearing (40.05.15.1.B; procedure in 50.35), then building plan review follows; confirm current turnaround times with Beaverton Planning and Building before scheduling a contractor., with plan check: Structural, energy, fire-separation and plumbing plan review is part of the building permit (Building Division); the land-use decision under 40.05.15 checks zoning only. Detached ADUs must be 6 ft from other buildings or meet the Residential Specialty Code's fire-separation rules.. Impact fees are System Development Charges from the city (transportation, water), Tualatin Hills Park & Recreation District, Clean Water Services (sanitary/stormwater) and Washington County (Transportation Development Tax) apply to a new dwelling unit; ADU treatment and any reductions are in the city's SDC handout B70-1116, unreachable on 9/20/2026. Ask the Site Development Division for a written SDC estimate before design.. Pre-approved plans: No Beaverton pre-approved ADU plan program was found on the city's site or in the Development Code as of Sept 2026; confirm with the Planning Division before assuming one exists..
| 1-Bedroom Rent | $1,400-$1,650/month |
| 2-Bedroom Rent | $1,600-$1,900/month |
| Annual Rental Income (est.) | $18,300/year |
| Payback Period (est.) | 12.7 years |
| Short-Term Rental | Not verified. |
| Overall ROI Estimate | 5-8% gross rental yield on a $165,000-$300,000 build at $1,400-$1,900/mo (estimate before taxes, vacancy and financing) |
A typical ADU in Beaverton generates approximately $18,300 per year in rental income based on average 1-bedroom rents. At an average construction cost of $232,500, the estimated payback period is 12.7 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: $70,000-$160,000.
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). See which cities offer pre-approved ADU plans.
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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