Draft Code Amendments

The Council has directed staff to pursue development code amendments to meet the minimum compliance provisions outlined in the administrative rules for middle housing contained within Division 46. While the state allows some flexibility for cities to modify their design and dimensional standards for middle housing, as long as the regulations are not more restrictive than those that apply to single-family detached homes, there is less flexibility for the adoption of other types of standards related to middle housing.

For more detail, see the full set of draft code amendments, now available for public review.


State requirements in Division 46 include relatively precise definitions of each middle housing type - Duplexes, Triplexes, Quadplexes, Townhouses, and Cottage Clusters – that must be adopted in order for cities to comply with the bill. The following amendments to LOC 50.10.003 – Definitions are needed:

  • Separate Triplex and Quadplex from definition of multi-family.
  • Add a definition for Cottage Cluster.
  • Revise definition for Courtyard to align with Cottage Cluster requirements.
  • Add a definition for Townhouse Project to align with Division 46


Per Division 46, middle housing must generally be allowed in any zoning district that allows single-family detached residential dwellings as a permitted use. In Lake Oswego, middle housing regulations will be now be allowed within the following base zoning districts:

  • Residential Low Density: R-15, R-10, and R-7.5.
  • Residential Medium Density: R-6, R-5, and R-DD.
  • Residential High Density: R-3, R-2, R-0, and R-W.

Though middle housing must be permitted broadly within these areas, Division 46 allows the City to prohibit or limit middle housing in areas that are protected under existing Statewide Planning Goals, under certain conditions. The City has already implemented several regulations in order to provide protections for goal-protected resources within code chapters such as the Greenway Management Overlay District (LOC 50.05.009), the Sensitive Lands Overlay District (LOC 50.05.010), the Flood Management Area (LOC 50.05.011), Hillside Protection areas (LOC, and Historic Preservation areas (LOC 50.06.009). These chapters generally already comply with Division 46, with a few exceptions. The Sensitive Lands Overlay District (LOC 50.05.010) must be amended to eliminate references to single-family residential zones, and to both allow and regulate duplexes in the same manner as single-family dwellings within these areas.

Use Standards

As mentioned above, Division 46 requires that middle housing types be allowed broadly in most residential zones. This requires amendments to the use-related standards in LOC 50.03, including an extensive update to the Use Tables in LOC 50.03.002 to permit all middle housing types in the zones where they are required to be permitted.

Review Procedures

Division 46 also stipulates that middle housing must be subject to the same approval processes as single-family detached dwellings in the same zone. Under the City’s current system, single-family development is classified as a Ministerial decision, and the development of middle housing types other than duplexes is classified as a Minor Development decision and subject to additional staff review.

The review procedures detailed in LOC 50.007.003 must be amended to treat middle housing the same as single-family housing in order to comply with Division 46. At the work session on December 13, 2021, the Planning Commission concurred with staff’s recommendation to develop code amendments that would classify the development of a single triplex, quadplex, townhouse project, and cottage cluster as a ministerial decision in order to comply with the bill.


The City must eliminate any provisions related to maximum density in a number of residential districts (R-15, R-10, R-7.5, R-5, R-DD, R-W, and R-3) for middle housing types other than townhouses, as Division 46 prohibits cities from applying maximum density standards to duplexes, triplexes, quadplexes, and cottage clusters. With respect to townhouses, the CDC must be amended to allow a maximum density of at least four (4) times the density applied to single-family dwellings in that zone, or 25 units per acre –whichever is less.

Minimum compliance provisions of Division 46 also require cities to establish a minimum density for Cottage Cluster projects of at least four (4) units per acre. Though existing minimum density standards currently require more than four (4) units per acre in several zones, minimum density provisions in the R-7.5, R-10 and R-15 zones will need to be increased in order to comply with the bill.

Though the City’s ability to apply density standards is somewhat limited by the bill, the continued application of minimum lot area requirements will effectively control density to some degree.

Minimum Lot Area

Division 46 rules place limits on the City’s ability to apply minimum lot area standards to middle housing. However, even within these limits the rules do provide the City with some flexibility to modify minimum lot area requirements as an approach to managing density for some middle housing types.

The Planning Commission has recommended requiring that lots for triplexes, quadplexes, and cottage clusters generally be larger than what is required for single-family houses in the R-3, R-W, R-DD, R-5, and R-6 Districts. Based on this recommendation, the minimum lot size for a triplex in the R-5, R-DD, R-W and R-3 Districts would be 5,000 sq. ft., the minimum lot size for a triplex in the R-6 District would be 6,000 sq. ft., and the minimum lot sizes for quadplexes and cottage clusters would be 7,000 sq. ft. Because existing minimum lot sizes in the R-7.5, R-10, and R-15 zone districts are in excess of 7,000 sq. ft., under the Division 46 rules the minimum lot size for triplexes, quadplexes, and cottage clusters could not be increased to more than the minimum lot size for single-family dwellings in these zones.


Minimum compliance provisions for middle housing in Division 46 do not offer cities much flexibility with respect to off-street parking standards. Cities can require no more than 1 parking space per unit for all middle housing types.

The City’s existing parking requirement of 1 space per unit for single-family dwellings and duplexes complies with Division 46. However, off-parking requirements for multi-family developments, including Triplexes, Townhouses and Quadplexes, are calculated per bedroom, with a minimum requirement of 1 space per unit for studio/efficiency, 1.25 spaces per unit for 1 bedroom, and 1.5 spaces per unit for 2 or more bedrooms. The off-street parking requirements within LOC 50.06.002 – Parking must be amended to match this 1 space per unit requirement for all middle housing types. This will require the code to specifically address parking requirements for cottage clusters, which aren’t currently defined, as well as parking requirements for townhouses in zones where they are not currently permitted.

Middle Housing Conversions

Provisions within Division 46 require cities to apply different standards for conversions or additions to existing single-family dwellings to create middle housing than would be applied for new middle housing development or the redevelopment of middle housing. These standards are not permitted to discourage middle housing conversions or additions by creating unreasonable cost and delay when compared to new development on a vacant site. Division 46 provides no alternatives to these requirements.

In order for the City to comply with the special provisions for conversions of single-family dwellings required under Division 46, code amendments are necessary to the public works exceptions in LOC – Minor Development and LOC – Ministerial Development. Currently, these code sections provide the City with conditioning authority to require or defer public improvements for multi-family and townhouse developments, but not for single-family dwellings.

Division 46 also specifies that building design standards may not be applied to conversions or additions to a single-family dwelling that create middle housing. As a result, code language within LOC – Building Design, LOC – Lake Grove Village Center Overlay District, and LOC – Glenmorrie R-15 Overlay District must be modified to clarify that the design standards in these sections may not be applied to middle housing created through conversions or additions to a single-family dwelling.

Design and Dimensional Standards

As mentioned above, the state provides cities with some flexibility to modify their design and dimensional standards for middle housing, as long as the regulations are not more restrictive than those that apply to single-family detached homes.

City Council provided direction to staff to apply the existing bulk and massing standards (or “dimensional” standards) for single-family housing to duplexes, triplexes, quadplexes, and townhouse projects. Existing dimensional standards include zoning regulations such as minimum setbacks, maximum height, maximum lot coverage, maximum floor area ratio, front and side setback planes, and other standards, which together establish the basic building “envelope” on a lot. The graphic below illustrates how the City’s existing dimensional standards would be applied to the construction of a quadplex:

For the most part, the design and dimensional standards applicable to single-family dwellings would also apply to townhouses. However, there are some important distinctions that will need to be included in the code in order to correctly apply these standards.

For background, Division 46 provides the following definitions for a townhouse:

(17) “Townhouse” means a dwelling unit that is part of a row of two or more attached dwelling units, where each unit is located on an individual Lot or Parcel and shares at least one common wall with an adjacent dwelling unit.

This definition stipulates that townhouses must be attached structures with each unit located on its own individual lot, which makes them different from other middle housing. In order to address this difference, townhouse standards are typically applied to the entire site, rather than to individual townhouse lots. At their work session on January 10, 2022, the Planning Commission concurred with staff’s recommendation to apply bulk and scale controls to the entire townhouse project, instead of individual lots, consistent with the definition of “townhouse project” in Division 46:

(18) “Townhouse Project” means one or more townhouse structures constructed, or proposed to be constructed, together with the development site where the land has been divided, or is proposed to be divided, to reflect the Townhouse property lines and the any commonly owned property.

The graphic below shows the City’s dimensional standards as applied to a “townhouse project,” rather than each unit.

The City has also proposed to amend the code to specify that internal side setbacks are not required for townhouses along lot lines between attached units. In the zones that currently do not allow townhouses, an exemption from side setbacks will need to be added for lot lines between attached townhouse units.

Design and Dimensional Standards for Cottage Clusters

For cottage clusters, the minimum compliance track allows cities to adopt the following “siting standards” (or dimensional standards) defined in Division 46, or a less restrictive version of these standards:

  • Minimum Lot Size: No greater than 7,000 square feet or the minimum lot size applied to single-family houses in the same zone, whichever is greater.
  • Minimum Lot Width: No greater than single-family standard.
  • Maximum Density: May not be applied to cottage clusters, although a cottage cluster development must meet the minimum density of at least four (4) units per acre.
  • Minimum Setbacks: No greater than 10 feet
  • Minimum Separation Between Buildings: No greater than 10 feet.
  • Maximum Building Footprint: Must limit to less than 900 square feet.
  • Maximum Lot Coverage: May not be applied to cottage clusters.
  • Floor Area Ratio (FAR):  FAR standards may not be applied to cottage clusters.
  • Maximum Height: No lower than 2 stories.
  • Off-Street Parking: No higher than one space per unit.

The image below is an illustrative example of how these design and dimensional standards would be applied to cottage clusters:

Given the direction from Council and the nature of the Division 46 rules, there is little discretion for modification of most of these “siting standards”. However, the rules do allow for the City to define the minimum number of dwellings in a cottage cluster as well as to limit the overall floor area (size) of each dwelling in a cottage cluster.

The draft code amendments set the minimum number of units for a cottage cluster at five (5) as a means of differentiating requirements for cottage clusters from other forms of detached middle housing. This recommendation is consistent with Council direction to not permit detached quadplexes and avoids confusion with any future allowances of detached quadplexes. Additionally, this recommendation prioritizes neighborhood character by effectively requiring larger sites for cottage cluster housing.

The draft code amendments also further limit the size of units in a cottage cluster to more closely replicate the floor area permitted for single-family dwellings in a given zone, using the following approach:

  • Apply a maximum average floor area for each dwelling in a cottage cluster development of 1,000 square feet in medium and high-density zones (R-7.5, R-6, R-5, R-DD, R-3, R-2, R-0, R-W); and
  • Apply a maximum average floor area for each dwelling in a cottage cluster development of 1,200 square feet in low density zones (R-10, R-15).

The graphic below is an illustrative example of a cottage cluster development with an average floor area for each dwelling of 1,000 sq. ft.

These maximum floor area standards would be most comparable to current maximum floor area standards that apply to single-family dwellings, and would also account for the larger lot sizes that are required in lower density zones. The exact standards for each zone will be refined in the draft code language.

Garages and Driveways

Existing standards related to garages and driveways include limits on the number of driveways per lot, maximum width of driveways, limits on garage width, recessed garage requirements, and other design treatments (including elevated garage standards).

City Council provided staff with general direction to apply existing single-family housing design standards for driveways and garages to duplexes, triplexes, quadplexes, and townhouses. Additionally, the Council also provided direction to enhance existing single-family garage appearance standards to better address the negative visual impacts of front-facing garages and driveways, consistent with the neighborhood survey results.

Under the proposed code amendments, duplexes, triplexes, and quadplexes will be subject to the same driveway standards as single-family houses, which means they will be limited to one shared driveway per 75 feet of lot frontage. A single driveway will be required to be shared by all residents to access their parking space or garage stall. However, two driveways would be permitted on lots that have more than 75 feet of street frontage.

The proposed code amendments also include new limits on the maximum width of driveways to prevent unnecessarily wide driveways on townhouse lots. Under existing code, the maximum width of a driveway approach is limited to 12 ft. per parking space for single-family dwellings, but not to exceed 30 ft., while other uses are limited to a maximum driveway approach width of 24 ft. Applying existing driveway and garage standards to a townhouse project will allow for each townhouse unit/lot to have its own driveway, which is necessary for compliance with Division 46.

Because issues can arise when a townhouse project includes fewer townhouses or is located on a wider lot, as under the existing code the driveway approach could potentially be wider than the width of the garages themselves, the proposed code amendments further limit the width of driveways on smaller townhouse lots to less than the width of the associated garage.

Proposed code amendments also include changes to the garage appearance and location standards in LOC in order to discourage overly prominent garages that are incompatible with community character. These standards regulate how garages are integrated with single-family houses, and how garages integrate with duplexes and zero lot line dwellings where those housing types are permitted. Figure 50.06.001-L: Garage Design Requirements is shown below:

Proposed code amendments acknowledge that garage recessing is the most effective strategy to minimize the visual prominence of the garage, and now garage recessing will be required as opposed to simply being one available option for compliance. Images showing examples of middle housing with recessed garages are included below:

Proposed code amendments also modify the existing garage design standards to apply to narrow lots, which are very common for individual lots within a townhouse project. While the existing code exempts lots that are narrower than 50 feet from garage design standards, the proposed code amendments will now apply garage standards to lots that are narrower than 50 feet in width.

To further minimize the prominence of garages in the context of middle housing while balancing the need for flexibility, the proposed code amendments also include modifications to the garage design standards that apply differently depending on the width of the garage as a percentage of the front façade. The key concept is that if the garage makes up a larger portion of the front façade, then more techniques and treatments must be used to minimize the appearance of the garage from the street. The table below clarifies how the garage appearance and location standards described above would be applied:

Other amendments to these standards have been proposed in order to comply with Division 46, including modifications to the garage appearance and location standards so they do not scale by the number of dwelling units, but by the size of the lot or structure.

For more detail, see the set of draft code amendments that are now available for public review.

Contact Information

Erik Olson, Senior Planner, (503) 697-6524 or email.

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