Missing Middle Housing-- Roadblocks in Eugene Code

Two of the Pillars of Envision Eugene are to “Promote compact, urban development and efficient transportation options” and “Provide housing affordable to all income levels” Another is to “Protect, repair, and enhance neighborhood livability.”  Missing Middle Housing is a key method to increase our compact urban development and providing enough housing so that it remains affordable, while also protecting neighborhood livability by providing options to residents to meet different lifestyle needs in the same neighborhood, by providing housing options that are more consistent with the density levels of existing neighborhoods, and by allowing for incremental infill and change. However, Eugene’s code in practice limits many missing middle housing types throughout the city, or makes them very difficult to build.  The below looks at roadblocks to building different types of Missing Middle housing—twins/duplexes, cottages, secondary dwelling units, rowhouses/townhouses, and triplexes in R-1 zoned areas, and the medium density area in the Jefferson Westside Special Area Zone.

R-1 Zoning

91% of Eugene’s residential land is zoned R-1, intended for single-family homes.  Many missing middle housing types create housing that has an appropriate density level for R-1 zones—duplexes, cottages, and secondary dwelling units all create a density of less than or about 14 units per net acre, particularly if interspersed with single family homes.  However, these types are difficult to build, or prohibited in many areas of Eugene.

In addition, lot size and lot coverage requirements make it difficult, overall, to build smaller lot homes, with perhaps less home square footage (for those who need less space) or less yard to maintain (for those who can’t or don’t wish to do yard work.)  The minimum lot size, in most cases, in R-1 zones is 4,500 square feet, with 50% of the lot open (i.e. not covered by buildings or parking.)  This is despite the fact that an average lot size required to build 14 units per acre (the maximum in R-1) is 3,111 square feet.

A combination of the difficulty of the fact that the vast majority of Eugene residential land is zoned for R-1 usage, combined with restrictions on missing middle housing that meets unit-per-acre limits for R-1 and restrictions on buildings adjoining R-1 zones in order to protect single family homes (such as differing height limits for buildings in C-2 or higher density residential next to R-1) prioritizes detached single family homes over other housing types in Eugene.


Duplexes are defined in the code as “a building designed and used dwellings for two families… that are either connected by common walls or common ceiling/floor connection.” It excludes situations where there is a primary dwelling and a secondary dwelling as part of the same building from that of a duplex.  

Sample duplex:
Columbus, OH:  Two story duplex with two units, each approximately 1700 square feet with 2-3 bedrooms and 1.5 baths.  The lot size is about 7000 (50 feet by 140 feet) and the building footprint is 1700 square feet, leaving about 5300 square feet of additional space on the lot—a fairly large amount of open space. If there was a full acre of houses like this one, the net density would be 12 units per acre.

This duplex would not be allowed in R-1 in Eugene.

  • Duplexes are prohibited outright in the Amazon, Fairmount, and South University Neighborhoods.
  • In other neighborhoods, duplexes are only permitted on corner lots or as part of a subdivision plat (see below).  This duplex is the second lot in from the corner, so it would be prohibited.
  • Duplex lots must be at least 8000 square feet.  Though the net density is below the 14-unit-per acre max, the larger lot size required for duplexes would prohibit this house.


Cottages are smaller homes, typically less than 1000 square feet. In some cases, they are grouped into “clusters” of three or more cottages that share common open space.  Cottages are not described in the code—their closest equivalent would be a one-family dwelling.  

Sample single cottage:
One story, 600 square foot cottage with two bedrooms and one bath on a 3100 square foot lot.  There is 2,500 of open space on the lot. If a full acre of these houses were built, the density would be about 14 units per acre.  

This cottage would not be allowed to be currently build in Eugene R1 except as part of a cluster subdivision or planned unit development.

  • The lot size of 3,100 square feet is smaller than the lot-size of 4,500 allowed in R1. As a single home, and not part of a subdivision, it would not be allowed in R1.

Sample cluster:
Three 600 cottages similar the ones described above, on 9300 square feet of land.  The amount of open space would be 6,500 square feet.  If an entire acre were built with these types of cluster, the density would be 14 units per acre.

These would not currently be allowed to be built in Eugene R1 areas.

  • Because there are only three units, they do not meet the requirements of a subdivision (which requires four lots) or a cluster subdivision (6 or more lots.)
  • Partitioning the lot would create lots smaller than the minimum lot size, and wouldn’t be allowed.
  • Only one one-family dwelling is allowed per lot in R1. Because there are three dwellings here, configuring them as a “main dwelling” and “secondary dwelling” wouldn’t work.

Secondary Dwelling Units

Secondary Dwelling Units are homes that are located on the same lot as a primary home, but is clearly subordinate to the primary one-family dwelling.  They can be either attached or detached from the primary home.

Sample secondary dwelling unit:
A one story, 1,600 square foot home with 3 bedrooms and 2 baths has a 650 square foot, one-bedroom cottage in the back yard.  The lot size is 6,250 square feet. This leaves 4,000 square feet of open space.  If a full acre had homes like this, the net density would be 14 units per acre.

This housing would not be allowed in R1 under current Eugene code.

  • Secondary dwelling units are limited to 10% of the total lot size—a secondary dwelling unit larger than 625 square feet would not be allowed on 6,250 square foot lot.
  • This lot is also too small to be subdivided into two separate lots; the minimum lot size is 4,500 square feet, so lots smaller than 9,000 square feet can’t be subdivided.  Small lots in R1 can only be created as part of a planned unit development or larger subdivision.
  • Ownership requirements state that either the primary or secondary dwelling must be owner-occupied. While there are advantages to this, it reduces the flexibility and increases roadblocks to developing a secondary dwelling unit—for example, a situation that might be encountered is a homeowner needing to move to a new town because of an employment situation during a slow period in the housing market, and deciding to rent the house until the housing market improves and they can sell it. The ownership requirements would prohibit a home owner from having this flexibility if they also have a secondary dwelling unit. In addition, home owners with secondary dwelling units are required to provide documentation to the city every two years that they continue to reside on the property.
  • In the Amazon, Fairmount, and South University neighborhoods, secondary dwellings are even more restricted—they must be on lots at least 7,500 square feet large and can’t be more than 600 square feet unless the lot is larger than 9,000 (in which case they can be 800 square feet.)


As defined in code, rowhouses are a dwelling that shares one or more walls with one or more other dwellings, and is located on a rowhouse lot. A key distinction between a rowhouse and duplexes, triplexes, and fourplexes is that, while attached, each home is on its own separate lot, which allows for individual ownership of each home, as compared to duplexes where both units would typically have the same owner.  In addition, up to eight units can be attached in rowhouses.  Rowhouses form the backbone of many historical medium density neighborhoods and typically are narrower, two or three stories, and have some outdoor space, though typically much less than a standard single family home.

Sample Rowhouse:
Washington, DC: A two story, 1,750 square foot, three bedroom, 1.5 bath home, on a 1,600 square foot lot.  This home would have 725 square feet of open space, and if all units in an acre of land were row houses, the net density would 27 units.

Rowhouses are extremely limited in R1 areas.

  • A special zone, R-1.5 is designated for row houses. No areas in Eugene are, by default, designated R-1.5.  To develop row-house in R-1, one would have to request a zone change for the property to R-1.5. The area allowed by this is limited to the space needed for up to 8 row houses (12,800 square feet with a lot size of 1,600 per lot.)  
  • R-1.5 zoning is prohibited within 500 feet of any other areas with row houses—so one could build a group of 8 row houses on a block, with a maximum of 180 feet in width (which would be roughly half to 2/3rds of a block) and then no row houses on the next block before row houses could be built again.
  • Row houses lots can also only be created in subdivision created after August 2001 that contains 10 or more lots. (See below re: subdivisions.)  You cannot subdivide an existing lot into a row house lot without rezoning to R-1.5.
  • Row houses are prohibited outright in R-1 in Amazon, South University, and Fairmont neighborhoods.

Medium Density- Jefferson Westside Special Area Zone

Eugene’s R-2 code is designed for medium density. While the majority of the missing middle housing described above would create densities less than the 14 units per acre in the code for R-1 zones, townhouses and triplexes in particular create densities more appropriate for the R-2 density levels of 10-28 units per acre. Can this type of missing middle housing be built in R-2 areas?

First off, there are very few areas zoned R-2 in Eugene—about 6% of the land zoned for residential use is zoned R-2, compared to about 91% zoned for R-1.  Many of the areas zoned R-2 are not near our key transit corridors, so developing Missing Middle housing there, while providing options, would not increase walkability. Much of our developed R-2 land is being under-utilized, with single family homes built on it as opposed to denser housing types. The minimum lot size in R-2 remains 4,500 square feet, though small lots and townhome lots are easier to create.  Secondary dwelling units are not permitted in R-2 areas.

One of the largest areas of R-2 zoning, in the Jefferson Westside neighborhood just outside of downtown, recently had a special area zone put in place that created limits on the ability to create missing middle housing within that area as well.  Furthermore, it prohibits zone changes to C-1 community commercial—despite the fact that the New Frontier Market is a key example of the type of mixed use commercial that is appropriate in a walkable neighborhood, further neighborhood corner stores are prohibited under the special area zone.  While it is easier to create lower-density missing middle housing, like twins and secondary dwelling units, in the Jefferson-Westside Special Area zone than it is in R-1 zoning, the ability to create medium-density missing middle housing, like triplexes and rowhouses/townhomes is blocked.


Twins/Duplexes would be allowed on lots over 4,500 square feet in Jefferson Westside. If all property on an acre were twins/duplexes on 4,500 square foot lots, there would be 19 units.


The three cottage cluster would not be allowed in the Jefferson Westside Special Area Zone—at 9,300 the number of units permitted on the lot 2.06, rounded down.  

The one cottage situation may be possible, if a lot over 6,750 square feet is divided into a lot 4,5000 square feet and 2,250 square feet.

Secondary Dwelling Units:

Secondary Dwelling Units would be allowed on lots over 4,500 square feet in Jefferson Westside. If all lots on an acre included a secondary dwelling unit, the net density would be between 10 and 20 units in the acre.  


Rowhouses/Townhouses would not be permitted in Jefferson Westside.

  • Though rowhouses are explicitly permitted in the R2 zoning, their lot size minimum is 1,600. Jefferson Westside dwelling-per-lot requirements prevent new dwellings on lots smaller than 2,250 square feet, and require a minimum frontage of 45 feet.  In addition, requirements for setback would prevent the construction of attached units on separate lots. This would prohibit the creation of rowhouse lots in Jefferson Westside.  


Triplexes are defined as “a building designed and used as dwellings for three families… that are either connected by a common walls or common floor/ceiling connections.”  

Sample triplex:
Troy, NY:  Two story, 3,000 square foot house converted into three apartments—a 600 square foot 1 bedroom, a 900 square foot two bedroom, and a 1,500 square foot three bedroom.  The lot size 5,230 square feet, leaving 2,230 square feet of open space.  If a full acre was built with homes like this, the net density would be 25 units per acre.  If the remainder of the acre were built with one or two unit homes on similarly sized lots, the net density would be between 10 and 18 units per acre.

This home would not be allowed in the Jefferson Westside Neighborhood.

  • The Jefferson Westside Special Area Zone code sets the number of dwellings permitted on a lot of particular sizes.  1 dwelling permitted on lots between 2,250 square feet and 4,499 square feet; two on lots between 4,500 and 8,999 and one dwelling per 4,500 square feet for lots larger than 9,000 square feet. However, for lots larger than 9000 square feet, the number of permitted dwellings is rounded down, so to build three units on a lot, one would need to have a lot size of at least 13,500—the maximum lot size allowed in the Jefferson Westside neighborhood.  While there is a clause that allows for one-two additional units on lots that are over 9000, no individual building may have more than two units, thus preventing triplexes.

Subdivisions and Infill

Infill is defined typically as the use of land within a built-up area for further construction.  It is a way to gradually increase the amount of housing in an area, without needing to build much additional infrastructure or radically and suddenly change the character of the neighborhood.  Infill also produces buildings in the same neighborhood of different ages, sizes, and types which can increase the diversity of price points for housing in a neighborhood.

Subdivisions, on the other hand, are defined in the Eugene code as dividing a larger lot or plot of land into at least four smaller plots.  While it is possible to take, for example, two or three lots and make a small four home subdivision, this would be very uncommon. Small lots are only permitted in R1 as part of a subdivision or planned unit development, for which the permitting process is much more onerous.  Furthermore, the code indicated that subdivisions must be at least 50% single family homes or townhouses—duplexes are limited to 25% of a subdivision, triplexes to 15% and fourplexes to 10%.

While Eugene’s code says that it’s goal is to promote infill, with the exception in some places of accessory dwelling units—which by their nature are rental units as opposed to smaller homes than can be owned—the ability to create additional units through infill of missing-middle style houses is difficult, and in practically limited to those creating large developments on large plots of land.