ADU construction costs
An ADU is a separate living space with its own kitchen and bathroom. Compare attached, detached, and conversion projects with utilities and site work identified.
Planning benchmarks: These ranges are national unless a row explicitly says Oregon or Washington statewide. Portland Metro prices have not been independently verified. Actual bids depend on the property and specified work.
Installation and project cost
Start with the project scope below. Installed totals include the work described in that row; repair, replacement, and construction scenarios are separate alternatives. Confirm removal, preparation, permits, delivery, and finish work in the written bid. Do not add overlapping totals together.
| Project or option | Planning range | Basis and scope |
|---|---|---|
| ADU cost | $100 – $300 | per sq ft; ADU construction |
| ADU cost | $60,000 – $180,000 | 600-square-foot ADU |
What the project can include
- Design and living-space construction
- Kitchen and bathroom
- Utility connections and site improvements
What changes the price
- New build versus conversion
- Unit size
- Utility routes and finish level
Ask for separate allowances for preparation, removal, delivery, materials, labor, and finish restoration where they apply.
Planning details and comparisons
Compare attached, detached, prefab, and conversion options separately. Confirm site feasibility and the utility connection allowance before treating a building-only budget as a completed ADU.
Before you request local bids
Share measurements, photos, the property location, existing conditions, desired materials, and your target schedule. Ask each professional to quote the same written scope, list exclusions and allowances, and identify any design, permits, utility work, disposal, or restoration that needs separate pricing.
Use the contact form to describe your project and request follow-up for Portland Metro.