Portland, OR - ADU Regulations - ADU rules and regulations

In a proactive effort to combat the ongoing housing crisis, the State of California has adopted specific regulations to promote the construction and utilization of Accessory Dwelling Units (ADUs). Here's an expanded and comprehensive breakdown of the key points:

1. Purpose and Prominence: California recognizes the potential of ADUs in providing affordable housing options. Given the state's dense urban centers and escalating property prices, ADUs present a viable solution to address the growing demand for residential spaces.‍

2. Eligibility for Establishment: Both single-family homes and multifamily properties can host an ADU.‍

3. Size Considerations: For detached ADUs, the maximum allowable size is up to 1,200 square feet.
The actual size of an ADU might vary depending on specific factors such as the total lot area and the size of the primary dwelling on the property.

4. Parking Norms: The state mandates limited parking requirements for ADUs.
If an ADU is situated near public transit, these parking stipulations may be even less stringent, facilitating easy construction and usage.‍

5. Owner-Occupancy: Historically, some jurisdictions required the property owner to live in either the primary home or the ADU. However, for ADUs permitted between 2020 and 2025, the state does not enforce such owner-occupancy requirements, allowing for greater flexibility in usage.

6. Setback Rules: For detached ADUs, there's a minimum setback requirement of 4 feet from both the rear and side yard boundaries.‍

7. Approval Process: Cities across the state are obligated to approve compliant ADU applications within a span of 60 days. This streamlined process ensures quick turnarounds and encourages homeowners to consider ADU development.‍

8. Fee Structure: To further incentivize ADU establishment, the state has reduced or completely waived fees for ADUs that are less than 750 square feet. This can translate to significant savings for property owners.‍

9. Rental Conditions: If an ADU meets the stipulated requirements laid out by the city, it must be available for rental. This regulation ensures that ADUs actively contribute to alleviating housing shortages.‍

10. Local Jurisdictional Variances: While the above guidelines provide a general framework, it's crucial to note that local jurisdictions might have their unique sets of regulations and requirements. Property owners should consult their respective city or county planning departments to get precise and localized information.

In conclusion, as California grapples with housing challenges, ADUs offer a promising avenue to augment living spaces without the need for expansive new developments. These guidelines, though comprehensive, serve as a starting point, and it's always recommended to liaise with local experts for tailored advice.

State laws (RCW 36.70A.680 and 36.70A.681) mandate that all local governments under the Growth Management Act (GMA), irrespective of size and including both cities and counties within unincorporated urban growth areas, update their regulations to align with specific criteria within six months following their scheduled update. The key directives include:

ADUs per Lot: Urban areas within the GMA must allow at least two ADUs on any lot that qualifies by size, in addition to the main residence. These ADUs can be attached, detached, or a mix, and converting structures like garages into ADUs must be permitted.
Size Requirements: ADUs cannot be restricted to under 1,000 square feet.
Design and Location Standards: Restrictions on setbacks, lot coverage, tree preservation, or entrance placements cannot be stricter than those for the main home.
Street Upgrades: ADUs cannot be subjected to demands for street improvements as a permit condition.
Owner Occupancy: Requirements for the homeowner to live on-site are prohibited for both the main and accessory units.
Condominium Sales: It’s not allowed to block the sale of a condominium developed as an ADU on the basis that it’s an ADU.
Design Review: ADUs cannot face stricter aesthetic or design criteria than the primary residence.
Parking: Parking requirements are limited, with specific conditions for smaller lots and exemptions for ADUs near major transit hubs.
Impact Fees: Charges for ADUs are capped at 50% of those for the main house.
Common Interest Communities: New developments with homeowners associations are barred from implementing rules against ADU construction. However, existing regulations can remain.

These regulations aim to encourage the development of ADUs, offering more housing options within urban growth areas.

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Since July 1, 2018, most Oregon cities and counties allow homeowners to build Accessory Dwelling Units (ADUs) on residential properties. However, local rules on ADU size, placement, and design must be followed. Each area has its own rules for:

How big the ADU can be;
Where it can be located; and
If it needs to look like the main house.

Local governments also have different processes for giving permits and may charge fees for building an ADU. These fees, including impact fees or system development charges, can vary a lot. Some places might not charge these fees at all, while others could charge $15,000 or more for each ADU.

In Oregon, the rules for creating Accessory Dwelling Units (ADUs) set standards to boost housing while keeping communities looking good. Understanding Oregon's ADU laws is crucial for compliance and making the most of ADU benefits. Cities must have over 2,500 people, and counties over 15,000, to fall under the ADU mandate. This supports urban housing needs. Urban Growth Boundaries (UGBs) define where ADUs can be built, promoting smart growth and land use without harming Oregon's landscapes.

Oregon's ADU laws aim to increase affordable housing. They require local governments to process ADU applications efficiently, especially in urban areas. State laws stop local rules from demanding owners live in ADUs or provide extra parking, except for vacation rentals. Setback requirements ensure ADUs are well-placed, respecting privacy and the environment. Oregon encourages updating local ADU rules to match state standards, making it easier to build ADUs and help with housing shortages.

Design and siting rules for Oregon ADUs ensure they fit well with urban settings and offer design flexibility. Oregon prefers less restrictive rules for ADUs compared to other buildings, aiming to increase housing options responsibly. The state simplifies ADU regulations, replacing complex zoning laws with clearer, state-wide standards. This helps reduce red tape and encourage ADU construction.

Oregon's approach to ADUs, including size restrictions and utility connection guidelines, is designed to integrate ADUs smoothly into neighborhoods, addressing housing needs. ADUs can't be too large compared to the main house, and shared utility connections are encouraged to keep costs down. This effort shows Oregon's commitment to innovative, affordable housing solutions.

Oregon ADU laws establish criteria to support housing while maintaining community aesthetics.

Cities over 2,500 people, and counties over 15,000, need to allow ADU construction per state mandates.

Urban Growth Boundaries (UGBs) are key to ADU development, limiting expansion within set geographic areas.

The state prohibits local ordinances from requiring owner occupancy or off-street parking for ADUs, except for vacation rentals.

Oregon mandates setback requirements for ADUs to ensure privacy and environmental standards.

Local governments in Oregon must update regulations to align with state ADU codes, promoting consistent and simplified ADU development.

Oregon ADU laws facilitate affordable housing by removing barriers to ADU construction and simplifying the application process.

Design standards for ADUs in Oregon are clear and objective, not requiring ADUs to mimic the primary residence's architecture.

Oregon's policies allow ADUs more flexibility in development compared to other accessory structures, avoiding strict lot size or coverage constraints.

ADUs in Oregon are subject to size limitations, generally not exceeding 75-85% of the primary dwelling's floor area, with specific square footage caps.

The state encourages the use of shared utility connections for ADUs to lower construction and development costs.

Oregon's comprehensive ADU regulations aim to expand housing options, reduce bureaucracy, and accommodate the state's diverse housing needs.

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Permissible allowances:

ADUs are permitted in Residential, Commercial, and Central Employment (EX) zones. On sites with a house, attached house, or manufactured home, one ADU is allowed. In RF through R2.5 zones, the site must also meet the eligibility criteria for a primary structure as per 33.110.202, and sites with an attached house must satisfy a minimum size requirement (refer below).

In R20 through R2.5 zones, a single ADU is permitted on sites with a duplex (two units within a single detached structure) if the sites have frontage on a City-maintained street or pedestrian connections exclusively designed for pedestrians and bicycles, which connect to a City-maintained street. In multi-dwelling, commercial, and EX zones, one ADU is allowed on sites with a duplex, regardless of the City's maintenance of the street. In all cases, on a site with a duplex, the ADU must be detached from the duplex.

In certain circumstances, up to two ADUs may be allowed:

In R20 through R2.5 zones, two ADUs are permitted on sites with a house, attached house, or manufactured home, provided the site meets the minimum size threshold, is not located in the Constrained Sites ("z") overlay zone, and has frontage on a maintained street or dedicated pedestrian connection to a maintained street. Only one of the ADUs may be internal. For sites with a duplex, only one ADU is allowed.

In multi-dwelling, commercial, and EX zones, two ADUs are allowed on sites with a house, attached house, or manufactured home, regardless of the site size or street frontage. Only one of the ADUs may be internal to the primary structure on the site.

ADUs are not permitted in conjunction with other development types such as triplexes, fourplexes, floating homes, or multi-dwelling structures.

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ADU Size Allowances

General: The maximum size of an accessory dwelling unit (ADU) cannot exceed 75% of the living area of the primary structure (or larger unit in a duplex), or 800 square feet, whichever is less. However, this size limit does not apply to an ADU proposed within a primary structure's basement that is at least five years old. The living area is calculated by excluding certain areas from the overall building area, such as the thickness of exterior walls, garage areas, basement areas with a ceiling height less than 6 feet 8 inches, and any other areas inaccessible by a stairway or with a floor-to-ceiling height less than 5 feet.

For example, if an existing house has a living area of 1,000 square feet after subtracting the above-mentioned areas, the ADU size is limited to 750 square feet. In the case of a house with a living area of 2,500 square feet, 75% of the floor area would be 1,875 square feet. However, the ADU size is still limited to a maximum of 800 square feet.

Additional Requirements for Detached or Connected ADUs: In addition to the size limitations mentioned above, detached or connected ADUs are subject to the following conditions:

Height: The maximum height for a detached ADU is 20 feet when located outside of the required setbacks for the zone. If a detached ADU is allowed within the required setbacks, the maximum height is 15 feet.

Building Coverage: The building coverage for a detached ADU cannot exceed the building coverage of the house, attached house, or manufactured home. The combined building coverage for all detached accessory structures must not exceed 20% of the total site area.

Location: Detached ADUs must be set back 40 feet from a front lot line or behind the rear building wall of the primary structure.

Exterior Details: For detached ADUs taller than 15 feet, additional standards apply to the exterior. The exterior finish materials, roof pitch, trim, eaves, window orientation, and dimensions must match those of the house, attached house, or manufactured home in type, size, and placement, or they must be made from specific materials such as wood, composite boards, vinyl, or aluminum products composed in a shingle pattern or a horizontal clapboard or shiplap pattern with boards 6 inches or less in width. The detached ADU must also meet certain standards for roof pitch, trim, windows, and eaves. Refer to Section 33.110.250 for Single-dwelling zones or 33.120.280 for Multi-dwelling, Commercial, or EX zones.

ADUs in historic designations (33.445) may be subject to additional design requirements. These ADUs must comply with the Community Design Standards (33.218) if allowed, or they must be approved through Historic Resource review.

Floor Area: Floor area limits apply in all zones except RF, and in the R10 and R20 zones, the limits only apply to lots smaller than 10,000 sq. ft. In the R7 through R2.5 zones, additional floor area is earned for each proposed ADU.

Parking: An ADU does not require additional on-site parking. However, if parking is required for the existing dwelling unit(s), it must be retained or replaced on-site. Any replacement parking must meet the parking standards outlined in Chapter 33.266 of the Portland Zoning Code.

Minimum Lot Size for ADU proposals in the RF zone: When proposing one ADU, the minimum lot size can be found in Section 33.110.202 for When Primary Structures are allowed.

Minimum Lot Size for ADU proposals in the R20 through R2.5 zones: When proposing one ADU on a lot with a house or manufactured home, the minimum lot sizes are specified in Section 33.110.202 for When Primary Structures are allowed.