ADU Cost in Portland
An accessory dwelling unit in Portland typically costs 150,000 to 350,000 dollars to build, depending on size, type, and finishes, with detached units at the higher end and garage conversions at the lower end. Exterior choices like roofing, siding, and windows shape both the budget and how well the ADU matches the main home. ADUs are popular in Portland for added living space and rental income.
ADU cost by type
The type of ADU is the biggest cost factor in Portland.
| ADU type | Typical Portland cost |
|---|---|
| Garage or basement conversion | 100,000 to 200,000 dollars |
| Attached addition ADU | 150,000 to 300,000 dollars |
| Detached new build ADU | 200,000 to 350,000 dollars and up |
Exterior choices that shape an ADU
Roofing, siding, and windows are a meaningful share of an ADU budget and decide how well it blends with the main house. Matching the roof line and siding to the primary home helps the property read as one cohesive lot and supports resale. Durable, low maintenance materials like fiber cement siding and quality roofing keep an ADU looking good as a long term rental. Portland allows ADUs on most residential lots, which is why they are so common here.
Frequently asked questions
How much does an ADU cost in Portland?
Typically 150,000 to 350,000 dollars, with garage conversions at the lower end and detached new builds at the higher end, depending on size and finishes.
What type of ADU is the cheapest?
A garage or basement conversion is usually the cheapest ADU because it reuses an existing structure, while a detached new build costs the most.
How big can an ADU be in Portland?
Portland allows ADUs on most residential lots with size limits set by code. Confirm current size and height limits with the city before you design.
Do ADUs add value in Portland?
Yes. ADUs add living space and potential rental income and are in demand in Portland, which supports property value when built well and permitted.