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Municipalities can take concrete actions to encourage the development of missing middle housing. These strategies address three main barriers to constructing missing middle housing in communities: resident opposition, market demand, and zoning.


Determine Appropriate Missing Middle Housing Types for Different Areas

Missing middle housing can be appropriate to almost all areas, however, not all types are appropriate to all areas. Ultimately, it is up to the individual municipality to determine what types are appropriate.

Landscapes3 is Chester County's guide for future growth. The plan identifies both rural resource and growth areas within the county. Municipalities can work to create new housing units while preserving open space by focusing new housing, including missing middle housing, in growth areas. Within growth areas, development should be encouraged in underutilized commercial areas, Greyfields, and established neighborhoods (those with the infrastructure to support new housing). Mixing missing middle housing into existing neighborhoods conserves open space while meeting the need for increased units of housing. Lower density Missing Middle types, such as duplexes, twins, triplexes, quadplexes, and townhomes can be particularly well suited to single-family detached neighborhoods as they have minimal increases in impact when compared to a new single-family detached unit. Medium and Higher density Missing Middle types such as courtyards and appropriately scaled multiplexes are well suited to denser neighborhoods as well as part of redevelopment of existing commercial areas into mixed-use communities.

Missing Middle Housing is not intended to result in tear downs of existing residential areas but can be incorporated into these neighborhoods. ADUs and single-family housing conversions can add units without replacing buildings. Twins, townhomes, and duplexes can exist at similar scale to single-family detached housing and can be appropriate in or next to lower density single-family residential neighborhoods where land or parcels are available for development. Courtyard and cottage court housing styles can provide single-family detached units while utilizing less total land.

Commercial and some industrial locations can be appropriate to higher density housing. These areas can work well for large-scale apartment buildings; however, higher density missing middle housing types can be appropriate when large-scale apartments would be provide too much density for the area. Live-work units are especially appropriate for commercial areas. Adaptive reuse, medium multiplexes, townhomes, courtyard, cottage court, and live-work can all be appropriate for commercial and light industrial areas.

Encourage residential growth near amenities

Municipalities can address resident concerns by encouraging development near amenities. These amenities can include public transportation, medical facilities, public buildings, employment hubs, and retail businesses. Developing near amenities has multiple benefits including:

  1. potentially shortening transportation trips and encouraging alternative forms of transportation, therefore decreasing overall traffic.
  2. Helping to keep seniors socially and physically connected.
  3. Promoting health and exercise through walking.

Creating additional zoning opportunities can result in the newly allowable housing types to become more profitable than the existing stock. Municipalities should ensure changes to their zoning are right-sized to the existing character. ADUs and home conversions can maintain existing neighborhood character while adding units. Duplexes, twins, and potentially townhomes can be used in less built out existing residential neighborhoods.


Zone for Missing Middle Housing

Often, missing middle housing is not being built because it is prohibited by current zoning regulations. However, zoning can be an effective tool for encouraging missing middle housing development. The approaches below describe actions that municipalities can take to encourage missing middle housing through zoning.

Municipalities can most effectively encourage missing middle housing by permitting it by-right in a variety of districts. Missing middle housing externally appears compatible with single-family detached housing, just with additional units internally. While not all missing middle typologies are appropriate everywhere, the variety of sizes and scales of Missing Middle housing types means there is usually at least one type of Missing Middle Housing that will match with existing neighborhood character. For example, ADUs and single family conversions would often be appropriate in lower density residential neighborhoods, while multiplexes and triplexes would match the character of downtown mixed-use districts. Special exception and conditional uses may allow missing middle housing. However, the additional hurdles associated with them dis-incentivize development. By-right approval processes are more streamlined and as such are more attractive to developers due to the reduced time frame, lower cost, and greater ease.

An example of allowing missing-middle typologies by-right is the Planned Apartment District in Tredyffrin Township. Subject to their special development regulations, the Planned Apartment District allows for construction of a wide variety of missing middle housing types including but not limited to twins, duplexes, quadplexes, and multiplex medium dwellings.

Multifamily is often defined as buildings with three or more units, placing triplexes and quadplexes in the same category as large-scale apartment buildings. By creating unique definitions for triples and quadplex units municipalities can expand the areas where they are permitted by-right while still being compatible with neighborhood character.

Driving is nearly a necessity for everyday life in Chester County. Therefore, assuring adequate parking is available to residents is generally needed throughout Chester County. However, reducing parking minimums can encourage development and may be appropriate for specific situations. For instance, areas near public transportation, senior housing, or student housing may require fewer parking spaces. Reducing parking minimums can reduce some burden to developers and property owners and encourage missing middle housing development.

An example of modifying parking minimums to promote missing middle housing is the unified mixed-use development in West Chester Borough. Allowed by-right in the Commercial Service District, the unified mixed-use development gives applicants a parking reduction if they provide affordable housing with community facilities (subject to defined criteria).

Pinckney Hill Commons was developed as a mixed-use development and features both multi-family units and townhomes.

Clear and planning approval processes for missing middle housing can encourage developers to build new housing. The reduced development costs due to efficient planning processes are often attractive to developers. For more information on streamlining approval processes see the Cost of Housing Guide.

Calculating fees based on building size instead of the number of units per building can also encourage Missing Middle housing. As an example, using a per unit fee of $10,000, the fees for a single family detached home of 2,500 would total $10,000 ($4 per square foot) verses a duplex building with two units of 1,250 square feet each would have total fees of $20,000 ($8 per square foot). While the building footprint for both units is the same, fees per unit create a far higher cost per square foot for Missing Middle housing. Creating a unified fee per square foot encourages all housing types at the same level.

Short-term rentals can be a concern for communities that may come up while planning for Missing Middle housing. Municipalities often address these concerns by restricting short term use by type, such as creating specific restrictions for ADUs. This puts additional barriers onto Missing Middle housing types that are not placed on single-family and multifamily apartments. To address this, municipalities should create separate policies for short-term rentals that are applied across all residential housing types. For more information on zoning for short-term rentals view the Chester County Planning Commission’s eTool.

Zoning regulations that require lot dimensions per unit instead of per square foot put an unduly burden on Missing Middle housing types. For example, a minimum 5,000 lot area per dwelling unit regulation would require a 5,000 parcel for a single-family detached unit of 2,500 square feet, but would require a 10,000 lot for a duplex with two 1,250 square feet units, despite both having the same building footprint. To address this, regulations such as minimum lot size and set backs should be based on square feet and not unit counts.

Although not regulated by all municipalities, zoning districts which place maximum density requirements may preclude the establishment of ADUs. For example, if an existing zoning district permits a maximum of one dwelling unit per acre, and a minimum lot size of one acre, an ADU could effectively be prohibited if it is also classified as a dwelling unit resulting in 2 dwelling units where only 1 per acre is permitted. Establishing an exemption to allow for a single ADU on any lot, regardless of maximum dwelling units per acre should be considered.


Address Resident Concerns

Resident opposition, often referred to as NIMBYism ("not in my back yard"), can hinder new development including missing middle housing. Individuals' concerns are often related to the impacts of new housing to their community. These impacts include, but are not limited to: increased traffic, negative impacts on schools, decreased open space, decreases in home values, and preference for a single-family detached neighborhood. The following approaches are intended to help municipalities address residents' concerns and encourage missing middle housing in their communities.

Municipalities should work to ensure they understand all legitimate concerns behind resident opposition. Municipalities can conduct surveys, hold public outreach meetings, create online connection tools, or provide other methods for residents to directly communicate their concerns. Communication methods should provide for a diversity of response methods to ensure equitable distribution. For example, online methods should include options for call or mail-in responses for residents who may not have access to reliable online connection. Municipalities can encourage developers to hold public outreach meetings for larger projects when appropriate to help residents express concerns. Understanding concerns can help municipalities to mitigate negative impacts by altering projects and plans or to better educate residents on true impacts of missing middle housing typologies.

Municipal leaders need to ensure they have broad community buy-in when considering housing policy. It is more likely to hear from residents who have stronger concerns than residents who are neutral or in support of housing projects and plans. Additionally, important insight can be gained from other stakeholders—such as employees of local businesses who are currently priced out from living in the county. Outreach efforts can include discussions with local employers and non-profit organizations, conducting surveys or polls, and outreach to individual residents.

Opposition to missing middle housing can be based on over-inflated concerns over the impacts associated with new development. Understanding the real impact of missing middle housing can address these concerns. The Delaware Valley Regional Planning Commission (DVRPC) completed a report in 2020 on the effects of multifamily development. This report contains quantitative findings for the impact of multi-unit housing and can be an excellent resource for municipalities. Some highlights from the DVRPC report are below.

  • Parking. Additional units often increase the need for parking in a community. However, new missing middle housing can result in a similar net increase of parking needs compared to a new detached home. Missing middle homes often accommodate fewer people than detached single-family homes. These smaller households may have fewer vehicles than a family with teen drivers residing in a detached home. A duplex unit may only add one to two new vehicles per unit, or a total of two to four per building, while a detached unit may add one to four new vehicles per building. The DVRPC Multifamily study found that multifamily residents generate fewer vehicles per unit than single-family detached homes.
  • Traffic. Municipalities will need to understand and plan for traffic impacts associated with new housing units. However, these impacts will vary widely. Some new residents commute long distances, contributing to traffic; others may be moving closer to their place of employment, causing an overall decrease in traffic. This is becoming increasingly true as people work from home more. Like parking, much of this impact will be comparable in scale to the traffic generated by a single-family detached unit. The DVRPC Multifamily study found that multifamily residents generate fewer trips per unit than single-family detached homes.
  • Open space. When mixed into existing neighborhoods, missing middle housing will promote open space preservation by accommodating new growth on infill sites instead of open space. A diversity of homes, along with appropriate planning and zoning, can support the retention of open space. If the county’s forecasted 55,000 new homes were constructed on one acre lots, they would consume 66,000 acres of open space. The county could protect 51,000 acres of open space if instead a mixture of housing types including single-family detached, apartments, townhouses, and adaptive reuse were to be developed. Maintaining access for all residents to open space can help mitigate negative attitudes of new development. Municipalities should work to ensure that parks are within a half mile of residents. If not, they should develop these parks as missing middle housing is added.
  • School impact. Chester County demographics are shifting. The county has seen an increase in one person households and a significant portion of the population has been aging and are without school aged children. These demographic shifts indicate new housing will have a lower impact on schools than previously seen. Missing middle housing may also have a lower impact on schools than detached single-family homes. According to the DVRPC Multifamily study higher density homes with two or fewer bedrooms add less new school aged children per unit than detached single-family homes on average.
  • Density. Some resident opposition may be due to the conception of housing as either single-family detached or large-scale multi-family apartments. Missing middle housing is lower density than large-scale multi-family apartments, at a compatible scale to single-family detached housing, and is part of Chester County's community character. Municipalities can help assuage this concern by showing examples of existing missing middle housing within Chester County. Clearly communicating what missing middle housing is, and is not, may help to diffuse resident opposition based on density.
  • Home values. New affordable development, including missing middle and higher density apartment units, have been shown to not decrease and potentially even increase the values of nearby properties.


Provide Resources to Developers

Municipalities can share resources with developers to promote missing middle housing development.

Municipalities can create guides or pattern books of missing middle typologies to assist developers in understanding the type of desired housing. Municipalities can further encourage missing middle housing by establishing housing types that will be permitted by-right or that will receive a faster approval process. View Chester County Planning Commission's eTool for Affordable Housing Bonuses

Municipalities can offer density bonuses to incentivize the development of missing middle housing. Density bonuses increase the allowable density in exchange for meeting a public policy goal. Municipalities can offer density bonuses for providing affordable housing or public infrastructure to minimize potential impacts of new housing.

Many excellent resources are available on missing middle housing. Municipalities can share information to developers, residents, and employers from: