Grannio

Can You Build an ADU in Portland?

Yes — Portland is governed by Oregon's statewide ADU law, which limits what the city can restrict. A 700 sq ft detached ADU here runs about $176,500–$288,500.

Construction in Portland runs about 6% above the Oregon average, so budget toward the higher end of these ranges.

Detached ADU (700 sq ft)

$176,500–$288,500

Garage conversion (400 sq ft)

$55,000–$100,500

Statewide protection

Yes

What applies in Portland

Oregon's SB 1051 (2017) requires cities over 2,500 people to allow at least one ADU per detached single-family home, subject to reasonable siting/design standards, and bars added parking requirements and owner-occupancy mandates. HB 2001 (2019) expanded this to broader middle housing.

Because Oregon has a statewide ADU law (ORS 197.312 (SB 1051, 2017; HB 2001, 2019)), Portland must follow these minimums even where its older zoning code is stricter. Confirm fees and design standards with the Portland planning department.

Estimate your Portland ADU cost

Your property

ADU type

Estimated cost in Oregon

$176,500 – $288,500

≈ $252–$412/sq ft turnkey · midpoint $232,500

$158,000
Construction
$41,900
Design & permits
$32,600
Site work
Good news — building an ADU in Oregon is very likely allowed.
  • iSize set locally. This state leaves ADU size limits to your city — typical caps run 600–1,200 sq ft. Check your local code.
  • ✓No extra parking likely required. Cities cannot require additional off-street parking for an ADU under Oregon's statewide rules.
  • ✓No owner-occupancy requirement. You can rent out both the main home and the ADU — you do not have to live on the property.
  • ✓Lot has room. A 700 sq ft ADU uses about 12% of your 6,000 sq ft lot — comfortably within typical coverage limits.

Rule basis: ORS 197.312 (SB 1051, 2017; HB 2001, 2019)

If you rent it out

$1,150–$1,875

est. rent/mo

7.9%

gross yield

13.7 yrs

payback

~$17,019/yr after a 7% vacancy allowance, before financing & maintenance.

Financed over 20 yrs at 7.5%, the build is about $1,873/mo — vs ~$1,525/mo in estimated rent.

Get your detailed feasibility report →

Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.

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Other Oregon cities

SalemEugeneGreshamHillsboroBendBeavertonMedford

Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.