Portland allows one or two ADUs by right on any lot with a house, attached house or manufactured home in every residential, commercial mixed-use and EX zone under Zoning Code Chapter 33.205 (last amended by Ord. 191779, effective Oct 1, 2024); a duplex lot may add one detached ADU. The unit is capped at 800 sq ft or 75% of the main home's living area, whichever is less (a basement ADU in a house at least 5 years old is exempt), a detached unit may be 20 ft tall and must sit 40 ft back from the front lot line or behind the house, and in the R5, R7 and R2.5 zones a unit no taller than 15 ft can go right on the side or rear lot line. No off-street parking and no owner-occupancy are required (ORS 197A.425). The building permit fee is valuation-based (fee schedule effective July 10, 2026), and system development charges of roughly $11,400 or more (Parks $7,941-$11,878, Transportation $3,421, plus sewer) are waived if you record a 10-year covenant not to use the property as a short-term rental; the citywide 2025-2028 SDC exemption for new housing expressly excludes ADUs.
Zoning & Size Requirements [1][2][3][4]
Yes — Portland allows ADUs. A detached ADU can typically be up to 800 sq ft under current Oregon and Portland zoning rules.
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| Allowed Zones | Every residential zone (RF, R20, R10, R7, R5, R2.5 and the multi-dwelling RM zones) plus the commercial mixed-use and Central Employment (EX) zones, on a lot with a house, attached house, manufactured home or duplex (33.205.020). Not allowed with a triplex, fourplex, cottage cluster or multi-dwelling building. Check your base zone on the Portland Zoning App |
| Max Size (Detached) | 800 sq ft of living area or 75% of the main home's living area, whichever is less, measured after the ADU is built (33.205.040.C.1). Living area excludes exterior walls, garages and basement space under a 6 ft 8 in ceiling. Building coverage also cannot exceed the main house's, and all accessory structures together may cover at most 20% of the lot (33.110.245.C.3) |
| Max Size (Attached) | Same 800 sq ft / 75% cap as a detached unit; there is no separate attached or 1,000 sq ft limit. Exception: converting the basement of a house that has stood at least 5 years is exempt from the size cap entirely (33.205.040.C.1). On a duplex lot the 75% is measured against the larger of the two units |
| Max Size (JADU) | N/A (Oregon and Portland have no junior ADU category; a unit inside the house is simply an ADU under the same 800 sq ft / 75% cap) |
| Max Height | Detached or connected ADU: 20 ft (33.110.245.C.1). A unit built inside a required side or rear setback in R7, R5 or R2.5 is limited to 15 ft with 10-ft walls. Detached units over 15 ft must match the house's siding, roof pitch (or use 6/12), trim, eaves and window orientation (33.110.245.C.4). An ADU inside or attached to the house follows the house's 30 ft zone limit |
| Max Units | Up to 2 ADUs on a lot with a house, attached house or manufactured home; at least one must be detached, and in the R20-R2.5 zones the second needs Table 205-2 lot area and maintained-street frontage (33.205.020.B.2). One detached ADU with a duplex. With two ADUs (or an ADU plus a duplex) one unit on the lot must meet the visitability standards: a no-step entrance, a 60-in bathroom turning circle, 200 sq ft of level living area and 34-in doors (33.205.040.C.4) |
Setback Requirements [1][2][3][4]
Portland requires a rear setback of about 5 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 5 ft in R7, R5 and R2.5; 10 ft in RF, R10 and R20 (Table 110-4). In R7/R5/R2.5 a detached ADU may sit on the rear lot line (0 ft) if it is at least 40 ft from the front lot line, no more than 15 ft tall with 10-ft walls, within a 24 x 24 ft footprint, has no doors or windows facing that lot line and keeps dormers 5 ft off it (33.110.245.C.2.b) |
| Side Setback | 5 ft in R7, R5 and R2.5; 10 ft in RF, R10 and R20 (Table 110-4). Same 0-ft exception as the rear yard for a detached ADU that is 40 ft back from the front lot line, 15 ft or lower, and shows no doors or windows to the neighbour; on a corner lot it must also be 20 ft from the side-street lot line (33.110.245.C.2.b) |
| Front Setback | A detached or connected ADU must be at least 40 ft from the front lot line or sit behind the rear wall of the main house (33.205.040.C.2). Zone front setbacks are 10 ft in R5 and R2.5, 15 ft in R7 and 20 ft in RF, R10 and R20; a garage entrance needs 18 ft (Table 110-4) |
| Parking Required | None. No additional on-site parking is required for an ADU (city ADU zoning page, 2026), and ORS 197A.425(1)(b)(B) bars Oregon cities from requiring it; converting a garage does not require replacement parking |
| Owner Occupancy | Not required. Chapter 33.205 has no owner-occupancy rule and ORS 197A.425 prohibits one. The only occupancy condition is voluntary: the 10-year covenant against short-term rental of any structure on the property that you sign to get SDCs waived |
| Min Lot Size | One ADU with a house: the lot only has to meet the base-zone minimum for a primary structure (33.110.202); no separate ADU minimum. One ADU with an attached house: Table 205-1 (R5 2,500 sq ft, R7 3,500, R10 5,000, R20 10,000, R2.5 1,500). Two ADUs, or one ADU with a duplex: Table 205-2 (R5 3,000 sq ft, R7 4,200, R10 6,000, R20 12,000, R2.5 1,500) plus frontage on a City-maintained street |
Permit Process & Fees [5][6][7][8][9][10][11][12]
An ADU permit in Portland goes through a ministerial, by-right review. The city publishes no fixed ADU review time; plan review runs on DevHub with checksheet correction rounds, so allow for at least one. If a zoning standard is missed, the Adjustment Review alone takes about 8-10 weeks (city ADU zoning page, 2026). Permit fees: Building permit and plan-review fees are valuation-based under the Building and Other Permits Fee Schedule effective July 10, 2026 (no flat ADU fee); trade permits are separate. SDCs: Parks $7,941 (under 700 sq ft) or $11,878, Transportation $3,421, waived with the 10-year no-STR covenant.
| Approval Process | Ministerial building permit through Portland Permitting & Development (PP&D); no land-use review when the unit meets Chapter 33.205 and the base-zone accessory-structure standards. Steps: 1) check permit history, zoning, flood/slope hazard and tree rules on PortlandMaps; 2) optional free 15-minute appointments with a planner, building-code reviewer, water, sewer and transportation staff; 3) submit the building permit, site plan, architectural and structural plans, trade permits and the Residential SDC form as a single PDF on Development Hub PDX (write 'Pre-Approved ADU' if using a city plan set); 4) checksheet correction rounds; 5) pay fees and pick up the permit; 6) inspections booked on DevHub or 503-823-7000. Electrical work must be done by a licensed contractor even on an owner-built ADU. A unit that misses a zoning standard needs a discretionary Adjustment Review under 33.805 |
| Review Timeline | The city publishes no fixed ADU review time; plan review runs on DevHub with checksheet correction rounds, so allow for at least one. If a zoning standard is missed, the Adjustment Review alone takes about 8-10 weeks (city ADU zoning page, 2026) |
| Permit Fees | Building permit and plan-review fees are valuation-based under the Building and Other Permits Fee Schedule effective July 10, 2026 (no flat ADU fee); trade permits are separate. SDCs: Parks $7,941 (under 700 sq ft) or $11,878, Transportation $3,421, waived with the 10-year no-STR covenant |
| Impact Fees | System development charges apply unless waived: Parks FY2025-26 $7,941 for a unit under 700 sq ft or $11,878 for 700-1,199 sq ft (non-Central City; indexed each July 1); Transportation FY2026-27 $3,421 (dwellings under 1,200 sq ft, including ADUs, pay half the single-family rate); Environmental Services sanitary SDC by plumbing-fixture count plus a stormwater SDC on new impervious area (see BES schedule); Water none unless the meter is upsized. The ADU SDC Waiver (Revenue Division application, 10-year covenant that no structure on the property will be a short-term rental, running from final inspection; breaking it costs 150% of the then-current SDCs) removes the Parks, Transportation and BES charges. The citywide temporary SDC exemption for new housing (permits issued Aug 15, 2025 - Sep 30, 2028) expressly excludes ADUs (PCC 17.14.070.J) |
| Plan Check | Electronic single-PDF plan review on Development Hub PDX; paper plans by appointment only. New detached ADUs are reviewed under the Oregon Residential Specialty Code, conversions under the city's ADU Code Guide. A lot with 20% or steeper slope or in a landslide area needs a geotechnical report; a garage in a flood hazard area may not be convertible; trees with trunks over 12 in need protection measures |
| Pre-Approved Plans | Yes. The city offers 4 free pre-approved detached ADU plan sets (gable or shed roof, on a concrete slab or a wood-framed crawl space), adapted from the City of Eugene's plans. They are not suited to every lot: the shed-roof slab design exceeds the size allowed inside a side or rear setback, and the bathroom does not meet the visitability standard required when a lot has two ADUs. Truss packages can be a deferred submittal |
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Construction Costs [13]
Building an ADU in Portland typically costs $180,000-$280,000 ($250-$400 per sq ft); a garage conversion runs $70,000-$160,000.
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| Average Build Cost | $180,000-$280,000 |
| Cost per Sq Ft | $250-$400 |
| Garage Conversion | $70,000-$160,000 |
| Prefab ADU (Installed) | $100,000-$240,000 |
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Rental Income Potential [14][15]
A 2-bedroom ADU in Portland rents for around $1,700-$2,200/mo, an estimated 6-9% gross rental yield on a $180,000-$280,000 detached build at $1,400-$2,200/mo (estimate before taxes, vacancy and financing).
| Avg Rent (1 Bedroom) | $1,400-$1,700/mo |
| Avg Rent (2 Bedroom) | $1,700-$2,200/mo |
| Short-Term Rental | Yes, with a permit: an ADU can be a Type A accessory short-term rental (up to 2 bedrooms, stays under 30 days) under Chapter 33.207, or Type B (3-5 bedrooms) via 33.815.040.B.1. |
| Est. Annual ROI | 6-9% gross rental yield on a $180,000-$280,000 detached build at $1,400-$2,200/mo (estimate before taxes, vacancy and financing) |
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Recent Law Changes
What's Changed Recently
- Verified Sept 2026: Zoning Code Chapter 33.205 has not changed since Ord. 191779 (Zoning Code Update Packet #211, effective Oct 1, 2024). Packet #214 (Montgomery Park Area Plan, Ord. 192000, effective June 1, 2025) listed the chapter but left the ADU size, setback, lot-area and two-unit rules intact
- Fee updates: the Transportation SDC for FY2026-27 (from July 1, 2026) is $3,421 for a dwelling under 1,200 sq ft, including ADUs; the Parks SDC for FY2025-26 is $7,941 (under 700 sq ft) or $11,878 (700-1,199 sq ft) and is indexed every July 1; PP&D's Building and Other Permits Fee Schedule was reissued effective July 10, 2026
- Portland's temporary citywide SDC exemption does not cover ADUs. The ordinance City Council adopted in July 2025 exempts most new housing permitted between Aug 15, 2025 and Sep 30, 2028, but PCC 17.14.070.J excludes any accessory dwelling unit or caretaker quarters. ADU builders stay on the separate ADU SDC Waiver, which needs a Revenue Division application and a 10-year covenant against short-term rental
- Oregon HB 2138 (2025 session, passed June 2025): Sections 7-12 make any recorded CC&R or HOA rule that blocks an ADU or middle housing inside an urban growth boundary void and unenforceable, including instruments recorded before 2021; the change is operative Jan 1, 2027
- The state ADU mandate was renumbered: former ORS 197.312(5)-(6) is now ORS 197A.425. It still requires every city over 2,500 people to allow at least one ADU per detached house in single-family zones and bars owner-occupancy and extra-parking requirements (short-term rentals excepted)
- Since the 2021 Residential Infill Project (Ord. 190093, effective Aug 1, 2021): two ADUs per lot, a detached ADU on a duplex lot, no street-facing-entrance limit, and extra FAR for each ADU in the R7-R2.5 zones
Tips for Building an ADU in Portland
- To build on the side or rear lot line in R5, R7 or R2.5, keep the detached ADU at or under 15 ft tall with 10-ft walls, inside a 24 x 24 ft footprint, at least 40 ft back from the front lot line, and put no doors or windows in the wall facing the neighbour; otherwise the standard 5-ft setback and 20-ft height apply
- A basement ADU in a house that is at least 5 years old is exempt from the 800 sq ft / 75% cap, so a full-basement conversion can be larger than any new detached unit
- Sign the ADU SDC Waiver covenant unless you plan to Airbnb: it removes at least $11,362 (Parks $7,941 + Transportation $3,421) plus the sewer SDC, but it binds every structure on the property against short-term rental for 10 years from final inspection and costs 150% of the SDCs to undo
- Want two ADUs? One must be detached, the lot needs the Table 205-2 area (3,000 sq ft in R5) and frontage on a City-maintained street, and one unit on the lot must be visitable (no-step entry, 60-in bathroom circle, 34-in doors); the free city plan sets need bathroom changes to qualify
- Before you draw plans, pull the permit history on PortlandMaps (unpermitted work must be permitted first), check the Hazard section for flood and slope areas (20%+ slope needs a soils report) and note any tree with a trunk over 12 in, which needs protection
- Cost basis (2026-09-20 re-verification): build cost $180,000-$280,000 for a new detached ADU and $70,000-$160,000 for a garage conversion, $100,000-$240,000 for a prefab unit before site work, from a Portland design-build guide dated July 28, 2026 (industry, not a city figure); cost per sq ft $250-$400 is that range spread over a 600-800 sq ft unit. The same guide puts permit and plan-review fees near $1,900, an industry estimate the city does not publish. Rents: Zumper's Portland medians on Sept 19, 2026 were $1,400 (1 BR) and $1,699 (2 BR); new detached ADUs typically list above the citywide apartment median
- Cost basis (2026-09-20 re-verification): short term allowed: Yes, with a permit: an ADU can be a Type A accessory short-term rental (up to 2 bedrooms, stays under 30 days) under Chapter 33.207, or Type B (3-5 bedrooms) via 33.815.040.B.1. Not if the SDCs were waived: the covenant bars short-term rental of any structure on the property for 10 years
ADU Builders in Portland
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Portland Zoning Code Chapter 33.205 Accessory Dwelling Units (PDF dated 10/1/24, Ord. 191779) | Portland.gov Municipal Code — Accessed 2026-09-20
- Portland Zoning Code Chapter 33.110 Single-Dwelling Zones (Table 110-4 setbacks; 33.110.245 Detached and Connected Accessory Structures) | Portland.gov Municipal Code — Accessed 2026-09-20
- Accessory dwelling unit (ADU) zoning requirements | Portland Permitting & Development Planning Department — Accessed 2026-09-20
- 33.205 Accessory Dwelling Units - chapter page with Zoning Code Update Packet history | Portland.gov Municipal Code — Accessed 2026-09-20
- Accessory Dwelling Units (ADUs) - permit steps, fees, SDCs and pre-approved plans | Portland Permitting & Development Planning Department — Accessed 2026-09-20
- Apply for an ADU System Development Charge (SDC) Waiver | Portland Revenue Division Planning Department — Accessed 2026-09-20
- Temporary system development charge exemptions for new housing units (ADUs excluded) | Portland.gov Planning Department — Accessed 2026-09-20
- Portland City Code 17.14.070 System Development Charge Exemptions (Section J) Municipal Code — Accessed 2026-09-20
- Transportation System Development Charges (TSDC) rates July 1, 2026 - June 30, 2027 | Portland Bureau of Transportation Government Data — Accessed 2026-09-20
- Parks SDC Schedule FY2025/2026 | Portland Parks & Recreation Government Data — Accessed 2026-09-20
- Current fee schedules (Building and Other Permits Fee Schedule effective July 10, 2026) | Portland Permitting & Development Planning Department — Accessed 2026-09-20
- System Development Charges (SDCs) overview | Portland Permitting & Development Planning Department — Accessed 2026-09-20
- How Much Does It Cost to Build an ADU in Portland? (July 28, 2026) | PDX Remodeling & Design industry — Accessed 2026-09-20
- Zumper Portland, OR rent research (median 1 BR $1,400, 2 BR $1,699, data as of Sept 19, 2026) Market Data — Accessed 2026-09-20
- HUD Fair Market Rents Government Data — Accessed 2026-02-24
- ORS 197A.425 Accessory dwelling units (formerly ORS 197.312(5)-(6)) Government Data — Accessed 2026-09-20
- Enrolled House Bill 2138 (2025 Regular Session), Sections 7-12 amending ORS 93.277 and 94.776 Government Data — Accessed 2026-09-20
Frequently Asked Questions
Can I build an ADU in Portland?
Yes. ADUs are allowed in Every residential zone (RF, R20, R10, R7, R5, R2.5 and the multi-dwelling RM zones) plus the commercial mixed-use and Central Employment (EX) zones, on a lot with a house, attached house, manufactured home or duplex (33.205.020). Not allowed with a triplex, fourplex, cottage cluster or multi-dwelling building. Check your base zone on the Portland Zoning App in Portland. The maximum size for a detached ADU is 800 sq ft of living area or 75% of the main home's living area, whichever is less, measured after the ADU is built (33.205.040.C.1). Living area excludes exterior walls, garages and basement space under a 6 ft 8 in ceiling. Building coverage also cannot exceed the main house's, and all accessory structures together may cover at most 20% of the lot (33.110.245.C.3). Owner-occupancy is not required, so you can rent out the ADU.
How much does an ADU cost in Portland?
ADU construction in Portland typically costs $180,000-$280,000. Garage conversions run $70,000-$160,000, and prefab ADUs cost $100,000-$240,000.
How much can I rent an ADU for in Portland?
Average ADU rents in Portland are $1,400-$1,700/mo for a 1-bedroom and $1,700-$2,200/mo for a 2-bedroom unit.
Do I need parking for an ADU in Portland?
None. No additional on-site parking is required for an ADU (city ADU zoning page, 2026), and ORS 197A.425(1)(b)(B) bars Oregon cities from requiring it; converting a garage does not require replacement parking. Check with Portland planning department for the latest Oregon ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Portland?
Portland does not publish a standard ADU review timeline. plan review runs on DevHub with checksheet correction rounds, so allow for at least one. If a zoning standard is missed, the Adjustment Review alone takes about 8-10 weeks (city ADU zoning page, 2026). Permit fees: Building permit and plan-review fees are valuation-based under the Building and Other Permits Fee Schedule effective July 10, 2026 (no flat ADU fee); trade permits are separate. SDCs: Parks $7,941 (under 700 sq ft) or $11,878, Transportation $3,421, waived with the 10-year no-STR covenant.
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