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2026 Cost Guide · Updated July 2026

ADU Cost in Oregon — Portland, Eugene, Bend & Statewide

City-by-city ADU cost data across Oregon's major markets. Built from permit records, contractor data, and regional labor rates.

$140K–$380K Detached ADU range
$65K–$140K Garage conversion (lowest cost)
HB 2001 Statewide law guarantees 1 ADU/lot
SDCs waived Portland waives fees under 800 sqft
Oregon ADU front elevation, Craftsman-modern hybrid style
Oregon ADU kitchen interior Oregon ADU living room interior
Aerial view of an Oregon property with backyard ADU
Oregon ADU bedroom interior Oregon ADU bathroom interior Oregon ADU outdoor living and patio space
At a Glance

Oregon ADU costs — by type.

Detached ADU
$140K – $380K
$220–$380 per sq ft · Portland & Bend skew highest
🏡
Attached ADU
$120K – $320K
Shared utility hookups reduce connection cost
🔗
Garage Conversion
$65K – $140K
Portland's bungalow/craftsman stock is conversion-ready
🚗
Basement Conversion
$80K – $160K
Portland has a high share of homes with full basements
⬇️
Modular / Prefab
$180K – $280K
Reaches occupancy 4–6 months faster than site-built
📦
💡

HB 2001 guarantees an ADU on almost every lot. Since 2019, every Oregon city with 10,000+ residents must allow at least one ADU on any lot zoned for single-family housing — no owner-occupancy requirement, no design standards that make construction infeasible. Portland goes further, waiving System Development Charges entirely for ADUs under 800 sqft.

Calculate My ROI →
ADU Types

Which type fits your property?

01 / Most Common
Detached ADU
$140K – $380K

A 600 sqft detached ADU in Portland typically runs $200,000–$300,000 including permits — and Portland's SDC waiver for units under 800 sqft cuts upfront cost significantly versus other Oregon cities.

Detached ADU Guide →
02 / Most Affordable
Garage Conversion
$65K – $140K

Oregon's older housing stock — especially Portland's bungalows and craftsman homes — frequently has detached garages that are ideal ADU candidates, often with alley access that simplifies permitting.

Garage Conversion Guide →
03 / Fastest Timeline
Modular / Prefab
$180K – $280K

Several prefab ADU providers serve the Portland market. Prefab ADUs typically reach occupancy 4–6 months faster than site-built construction — a meaningful edge given Oregon's wet-season construction delays.

Prefab ADU Overview →
04 / Shared Utilities
Attached ADU
$120K – $320K

An addition sharing a wall with the main house. Shared utility connections reduce hookup costs versus a fully detached unit, and still qualifies for Portland's SDC waiver under 800 sqft.

Attached ADU Guide →
05 / Common in Portland
Basement Conversion
$80K – $160K

Portland's residential neighborhoods have a high share of homes with full basements, making this a cost-effective option. Main cost drivers are egress windows, a bathroom addition, and separate utility metering.

Basement ADU Guide →
Cost by Region

Every Oregon market is different.

Portland Metro
Portland · Bureau of Development Services
$220K–$380K
$290–$380 per sq ft
Highest cost
Bend / Central Oregon
Deschutes County
$210K–$360K*
$280–$360 per sq ft
Very high
Eugene / Springfield
Lane County
$180K–$290K*
$240–$310 per sq ft
Moderate
Salem Metro
Marion County
$165K–$270K*
$220–$290 per sq ft
Moderate
Medford / Ashland
Jackson County
$175K–$280K*
$230–$300 per sq ft
Moderate
Corvallis / Albany
Benton · Linn County
$165K–$260K*
$220–$280 per sq ft
Standard

*Total-cost ranges outside Portland are derived from regional $/sq ft data at a representative ~800 sq ft build; verify against local bids before publishing final figures.

Cost Factors

Why Oregon ADUs cost what they cost.

🌧️
Wet-Climate Construction
Oregon's wet winters (especially west of the Cascades) can slow exterior work — projects starting construction in fall commonly see weather-driven delays, and engineered drainage and quality roofing add real cost.
Adds timeline risk in fall/winter starts
📐
Oregon Residential Specialty Code
One of the stricter residential energy codes in the country. ADUs must meet current insulation, window performance, and mechanical efficiency standards — adding upfront cost but reducing long-term tenant utility bills.
Adds design & material cost statewide
👷
Portland Labor Market
Portland's construction labor costs run above the national average, pushing Portland metro toward the top of Oregon's cost range. Smaller cities like Corvallis and Salem see meaningfully lower labor costs.
Portland premium vs. rest of state
📋
HB 2001 Sets a Strong Statewide Floor
Every Oregon city with 10,000+ residents must allow at least one ADU on any single-family lot, with no owner-occupancy requirement. Portland goes further, waiving System Development Charges entirely for ADUs under 800 sqft — a $15,000–$30,000 saving unmatched by most other states.
Among the most ADU-friendly states
Homeowners reviewing ADU permit documents in Oregon
Permits & Fees

What permitting actually costs.

Oregon's costs are substantially lower than California, and Portland's SDC waiver makes it one of the most financially accessible ADU markets on the West Coast.

📄
Building Permit — Portland
$4,000 – $10,000
Based on project valuation.
🏗️
System Development Charges (SDCs)
$0 – $15,000
Waived entirely for ADUs under 800 sqft in Portland — in effect through at least 2027.
💧
Utility Connection Fee
$3,000 – $12,000
Sewer, water, and electrical connections.
📋
Plan Check Fee
$1,500 – $4,000
Structural/architectural review.
🧾
Total Typical Range
$18,000 – $40,000
Portland; lower in smaller Oregon cities.
Oregon Law
One of the most ADU-friendly states in the country.

HB 2001 (2019) requires every Oregon city with 10,000+ residents to allow at least one ADU on any single-family lot, bans owner-occupancy requirements, and prohibits design standards that make ADU construction infeasible. Portland has gone further, waiving System Development Charges entirely for ADUs under 800 sqft.

Statewide ADU lawHB 2001 (2019)
Minimum city population covered10,000+ residents
Owner-occupancy requirementBanned statewide
Portland SDC waiverWaived under 800 sqft
Short-term rental (Portland)Owner-occupied primary residence only
Contractor licensing boardOregon CCB
💡 Verify your contractor's CCB license first

Oregon requires all contractors to be licensed with the Construction Contractors Board. Verify at oregon.gov/ccb before hiring, and request references from at least three completed ADU projects — Portland's ADU contractor ecosystem is well developed, so there's no reason to skip this check.

Return on Investment

What an Oregon ADU returns.

$1,100–$2,200
Monthly rental income range statewide (sourced)
10–17 yrs
Modeled payback period (detached)*
$95K–$250K+
Added property value*
Has state tax
Oregon income tax runs up to 9.9%
Portland
$1,350 – $2,200/mo
1-bed monthly rent (sourced)
10–16 years
Modeled payback*
Bend
$1,450 – $2,050/mo
1-bed monthly rent (sourced)
10–17 years
Modeled payback*
Eugene / Springfield
$1,250 – $2,000/mo
1-bed monthly rent (sourced)
9–15 years
Modeled payback*
Salem
$1,100 – $1,575/mo
1-bed monthly rent (sourced)
10–16 years
Modeled payback*
Medford / Ashland
$1,000 – $1,500/mo
1-bed monthly rent (sourced)
10–17 years
Modeled payback*
Corvallis / Albany
$1,300 – $1,850/mo
1-bed monthly rent (sourced)
9–16 years
Modeled payback*

1-bed rent ranges verified July 2026 against current listings (RentCafe/Yardi Matrix, Zumper, Rent.com, Rentometer). *Payback and added-property-value figures are modeled (rent ÷ construction cost) and should be checked against local bids and actual project outcomes before publishing as final. Oregon has a progressive state income tax up to 9.9%, unlike Washington and Florida.

Save Money

7 ways to cut your
Oregon ADU cost now.

HB 2001 already guarantees your right to build. These moves target the design fees, timeline, and code costs that remain within your control.

Calculate My ADU ROI →
Compact detached ADU exterior with Craftsman-modern styling
🏡
Compact Detached ADU
Oregon — statewide range
Added Property Value
$95K–$250K+
1
Keep your ADU under 800 sqft in Portland
Portland waives System Development Charges entirely for ADUs under 800 sqft — a $15,000–$30,000 saving. Sizing your design to stay under that threshold is one of the single highest-leverage decisions you can make.
Saves $15,000–$30,000 in Portland
2
Convert a garage if your home has one
Oregon's older bungalow and craftsman housing stock — especially in Portland — frequently has detached garages with alley access already in place, which simplifies both permitting and utility connections.
Saves 40–55% vs. new construction
3
Start construction in spring, not fall
Oregon's wet winters can slow exterior work significantly. Projects that begin site work in spring get a full dry construction season before the fall rains return, avoiding costly weather-driven delays.
Avoids weather-driven schedule delays
4
Use an ADU-specialized design firm in Portland
Portland has several design firms that focus exclusively on ADUs and already know the Bureau of Development Services' review process, which can meaningfully compress the 60–90 day permit timeline.
Faster permit review, fewer revision cycles
5
Consider a basement conversion if you have one
Portland's high share of full-basement homes makes this a genuinely cost-effective option at $80,000–$160,000 — often cheaper than a new detached structure, with the main costs being egress windows and a bathroom addition.
Often 20–40% less than new detached construction
6
Budget for Oregon's energy code from the start
Oregon's Residential Specialty Code has stricter insulation, window, and mechanical efficiency requirements than many states. Pricing this into your initial budget avoids surprise costs mid-project, and pays back through lower long-term utility bills.
Avoids mid-project change orders
7
Verify your contractor's CCB license before hiring
Confirm any contractor's license at oregon.gov/ccb, and request references from at least three completed ADU projects. Portland's ADU contractor ecosystem is well developed — there's no reason to skip this step.
Prevents costly contractor disputes
Frequently Asked Questions

Oregon ADU answers.

Can I build an ADU anywhere in Oregon?
State law (HB 2001, 2019) requires all Oregon cities with 10,000+ residents to allow at least one ADU on every lot zoned for single-family housing. Cities cannot require owner-occupancy or impose design standards that effectively prohibit ADUs. Rural areas and smaller cities may have different rules — always verify with your local planning department.
Does Portland waive ADU fees?
Yes. Portland waives System Development Charges (SDCs) for ADUs under 800 sqft, which can save $15,000–$30,000 compared to other jurisdictions. This waiver applies to both detached and attached ADUs and is currently in effect through at least 2027.
What is Oregon's energy code requirement for ADUs?
Oregon has one of the stricter residential energy codes in the country (Oregon Residential Specialty Code). ADUs must meet current energy efficiency standards including insulation, window performance, and mechanical system efficiency. This adds cost compared to older construction but reduces long-term utility expenses for tenants.
Can I rent my Oregon ADU short-term?
Portland requires a short-term rental permit and limits short-term rentals to owner-occupied primary residences — meaning you generally cannot rent a detached ADU on Airbnb in Portland unless you live in the main house. Eugene and other Oregon cities have varying short-term rental rules; check local ordinances before planning.
How do I find an ADU contractor in Oregon?
Oregon requires all contractors to be licensed with the Construction Contractors Board (CCB). Verify any contractor's CCB license at oregon.gov/ccb before hiring. Portland has a well-developed ADU contractor ecosystem — request references from at least three completed ADU projects and get a minimum of three bids before committing.
What is the cheapest ADU to build in Oregon?
Garage conversions are the least expensive option, typically $65,000–$140,000. Oregon's older housing stock, especially Portland's bungalows and craftsman homes, frequently has detached garages that are strong conversion candidates, often with alley access already in place.
What is the ROI on an ADU in Oregon?
Oregon ADUs generate roughly $1,100–$2,200/month in rental income depending on city and size — Portland and Bend command the highest rents in the state. Unlike Washington and Florida, Oregon has a state income tax of up to 9.9%, which reduces effective rental returns somewhat. Modeled payback periods run roughly 10–17 years depending on market.
Oregon ADU exterior at twilight, warm interior light glowing
Imagine coming home to your own Oregon ADU.

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Cost Disclaimer: All cost ranges and estimates are approximations based on industry contractor data, published reports, and regional market research as of 2026. Actual ADU costs vary significantly based on lot conditions, city requirements, contractor selection, material specifications, and design complexity. Oregon's HB 2001 (2019) requires every city with 10,000+ residents to allow at least one ADU per single-family lot, with no owner-occupancy requirement, and Portland separately waives System Development Charges for ADUs under 800 sqft through at least 2027. 1-bedroom rent ranges shown were verified against current rental-market listings as of July 2026. Regional construction-cost totals outside Portland, and all payback-period and added-property-value estimates, are modeled figures rather than verified project outcomes and should be checked against current local bids before publishing as final. Always verify current zoning and permit requirements directly with your local authority before beginning design. Always obtain a minimum of three contractor bids before committing to a project budget. Last updated July 2026.