Portland · Cost guide
How much does an ADU cost in Portland? (2026)
Portland is one of the West Coast's most ADU-friendly markets thanks to HB 2001. But its SDC fee waiver — worth $7K–$12K on smaller ADUs — is set to expire in 2026. Here's the math, the urgency, and the ROI.
Last reviewed: 2026-06-14
Quick answer
In 2026, building a detached ADU in Portland typically costs $180,000–$280,000 all-in, while a garage conversion runs $90,000–$150,000. Per-square-foot costs range from about $200 (garage conversion) to $380 (premium detached). Portland's SDC waiver for ADUs under 800 sqft saves $7,000–$12,000 — but it expires in 2026.
⚠ Time-sensitive
The SDC waiver expires in 2026.If you file your ADU application after expiry, you'll owe the full System Development Charges — $10K–$25K on top of construction. For a 700 sqft ADU under the 800-sqft threshold, that's real money lost to a timing decision.
Want to lock in the SDC waiver? Tell us about your project and we'll connect you with up to three Portland ADU builders who can get your application filed. Free, no obligation.
Get matched with up to 3 Portland ADU buildersCost breakdown by build type
Total project costs in 2026 Portland — hard construction plus typical soft costs — for a mid-finish build. Historic inner-east neighborhoods (Hawthorne, Belmont, Sellwood) push to the top due to lot constraints and design review.
| Build type | Typical size | Total cost | Per sqft |
|---|---|---|---|
| Detached ADU | 600–1,200 sqft | $180K–$280K | $260–$380 |
| Garage conversion | 350–500 sqft | $90K–$150K | $200–$320 |
| Attached ADU | 500–1,000 sqft | $160K–$250K | $240–$360 |
| Junior ADU (JADU) | ≤500 sqft | $80K–$140K | $190–$320 |
| Prefab / modular | 400–1,000 sqft | $130K–$240K | $220–$320 |
The SDC waiver — Portland's key cost lever
Portland charges System Development Charges (SDCs) — transportation, parks, water, sewer impact fees — on virtually every new dwelling unit. For a typical ADU these add $10,000–$25,000 depending on size and utilities.
The city waives most SDCs for ADUs under 800 square feet. On a 700 sqft 1-bedroom you'd save roughly $7,000–$12,000— money that goes straight to your bottom line. Combined with Portland's relatively moderate construction costs, the waiver is the single biggest reason Portland is one of the cheapest West Coast cities to build an ADU.
The waiver expires in 2026.Applications filed after expiry will owe the full SDC. If you're planning to build, the smart move is to get your permit application in before the deadline — even if construction itself starts later.
The waiver applies to the permit application date, not construction date. Verify exact expiry timing with Portland BDS — fee waivers are political decisions and the cutoff has shifted before.
Hard costs vs. soft costs
On a typical Portland ADU project, soft costs are $13,000–$30,000on top of construction — but that's only with the SDC waiver. Without it, add $7K–$15K more.
Hard costs
- · Site prep, excavation, foundation
- · Framing, roof, exterior
- · Plumbing, electrical, HVAC
- · Insulation, drywall, paint
- · Cabinets, counters, appliances
- · Flooring, fixtures, finishes
Soft costs (Portland)
- · Design / architectural plans: $7K–$18K
- · Structural & energy engineering: $1.5K–$3.5K
- · Plan check + building permit: $3K–$8K
- · SDCs (waived under 800 sqft): $0 or $10K–$25K
- · Utility hookups (PGE / water / sewer): $0–$8K
- · Survey, soils, contingency: $1.5K–$4K
ROI — what a Portland ADU returns
Standalone backyard ADU 1-bedrooms in Portland typically rent for $1,500–$2,100/monthin 2026. Inner SE, NW, Pearl District at the top; outer East and outer SW lower. Portland's rental market has been flat-to-modest growth — don't budget aggressive rent appreciation.
Sample ROI — $215K detached 750 sqft ADU (with SDC waiver)
- · Construction cost: $215,000
- · Gross rent (1BR @ $1,800/mo): $21,600/yr
- · Net rental income after expenses: ~$17,500/yr
- · Cash-on-cash return: ~8.1%
- · Property value lift: $110K–$170K
- · Approx. rental payback: 12–14 years
How to lower the cost
1. File before SDC waiver expiry ($7K–$12K saved)
Time-sensitive — confirm current deadline with Portland BDS.
2. Stay under 800 sqft
The SDC threshold. Going over triggers full SDC charges.
3. Get 3+ written bids
Portland builder bids vary 25–35% for identical scopes.
4. Consider garage conversion
$90K–$150K vs $180K+ for new detached. Many Portland garages need significant code-upgrade work though.
When Portland ADU costs go up unexpectedly
- Historic district overlay. Hawthorne, Sellwood, Irvington, Ladd's Addition trigger Historic Review. Add 2–4 months + $5K–$10K.
- Steep / sloped lots. Common in SW Portland and parts of the West Hills. Retaining walls + foundation work add $15K–$50K.
- Old electrical service. Many pre-1980 PGE services need upgrade for ADU panel. Add $4K–$10K.
- Long sewer runs. Older inner-east neighborhoods sometimes need new sewer laterals. Add $5K–$15K.
- Filing after SDC expiry. $7K–$12K in fees you would have saved by filing earlier.
Sources
- Portland Bureau of Development Services — ADU permits ↗Official Portland ADU permitting information.
- Portland.gov — New Detached ADU Sample Fees ↗City fee schedule including SDC waiver details and sample permit fees.
- Apartment List — Portland Rent Report ↗Current 1-bedroom rent data for ROI estimates.
- Oregon Construction Contractors Board (CCB) ↗License verification for any Oregon ADU builder.
Last reviewed: 2026-06-14. Cost ranges are 2026 estimates and shift with materials and labor markets. Always verify the SDC waiver expiry and current fees with Portland BDS before making decisions.
Ready for real numbers on your Portland lot?
Share your project once and we'll connect you with up to three Portland ADU builders who know BDS permitting + the SDC waiver clock. Free, no obligation.
Get matched with up to 3 Portland ADU buildersSee also our free ADU cost calculator or the Oregon ADU guide.
Frequently asked
Portland ADU cost — common questions
How much does it cost to build an ADU in Portland in 2026?
In 2026, a detached ADU in Portland typically costs $180,000–$280,000 all-in ($260–$380 per square foot). Garage conversions run $90,000–$150,000. Portland is moderate cost for the West Coast — cheaper than Seattle, much cheaper than the California cities — but Oregon's SDC fees can add $10K–$25K on top if you build over 800 sqft.
What's the Portland SDC waiver and why does it matter NOW?
Portland waives System Development Charges (SDCs) — transportation, parks, water, sewer — for ADUs under 800 square feet. SDCs typically add $10,000–$25,000 to ADU project costs, so the waiver is a $7,000–$12,000 savings. The waiver is set to expire in 2026, meaning ADU applications filed after expiry will owe the full SDC. If you're on the fence, this is a clock that's running.
What's the cheapest type of ADU to build in Portland?
Garage conversions are usually cheapest in Portland at $90,000–$150,000 — you already have the foundation, walls, and roof. JADUs (carved out of existing main house) are similar at $80,000–$140,000 because they avoid new exterior construction. New detached ADUs cost the most at $180,000–$280,000.
How much rent can a 1-bedroom ADU in Portland get?
1-bedroom ADUs in Portland typically rent for $1,500–$2,100/month in 2026, depending on neighborhood. Inner SE, NW, and Pearl District command the top of the range; outer East Portland and outer SW run lower. Portland's rental market has been roughly flat for the past few years, so don't budget for aggressive rent growth.
What's the ROI on a detached ADU in Portland?
On a $215,000 detached ADU renting at $1,800/month, annual net rental income runs roughly $17,500 after expenses — a cash-on-cash return of about 8.1%. Property value typically lifts $110,000–$170,000. Portland's slower rent growth means the math depends more on the property value lift than aggressive rental yield.
How long does ADU construction take in Portland?
Plan on 12–16 months for a detached ADU: 2–4 months for design, 3–5 months for permitting through Portland's Bureau of Development Services (BDS), and 6–8 months for construction. Garage conversions run 9–13 months total. Older Portland inner-east neighborhoods (Hawthorne, Belmont) often add 1–2 months of historic review.
Do I need a contractor licensed in Oregon specifically?
Yes — Oregon requires builders to hold an Oregon Construction Contractors Board (CCB) license. Verify your builder's CCB number is active and check complaint history at oregon.gov/ccb before signing any contract. The license is state-level (not Portland-specific) and any active CCB-licensed contractor can build in Portland.
What's Portland's HB 2001 and does it affect ADUs?
Oregon's HB 2001 (2019) is the state's missing-middle housing law that eliminated single-family zoning in cities over 25,000. For ADU owners specifically, it means streamlined approvals and the right to build an ADU on virtually any residential lot. Portland implements HB 2001 through its Residential Infill Project, which also legalized triplexes and fourplexes on standard lots.