Cluster Housing

Issues Addressed:
Housing Options Infrastructure Sustainable Housing
A drawing showing an aerial view of same plot of land three times. Above there is a version labeled "Undeveloped," with a wooded area and a lake and stream. At bottom-left there is a version labeled "Conventional Subdivision." It shows the land divided into a ten parcels of relatively even size spread out across the area. There is a large amount of road and driveway area and many of the trees have been removed. At bottom-right is a version labeled "Cluster Housing." It shows twelve relatively small homes on twelve small parcels, clustered in two groups at the bottom-left of the area. The trees have been preserved, and only a small amount of road/driveway area connects the homes to the main edge of the area. Green trails wind throughout the parcel and connect to both the houses and the public road away from the houses. The Cluster Housing diagram has additional labels: "Preserved Natural Features," "Less Infrastructure," "Bonus units," and "Public access."

What is it?

Cluster housing (also called “conservation subdivision” or “open space subdivision”) is a style of development in which homes are grouped together on a site and given large shared open spaces, rather than the style of conventional development, with homes evenly distributed with smaller private open spaces. The practice mirrors historic patterns of neighborhood development before the rise of large-lot subdivisions. Towns can encourage and developers can pursue cluster development to preserve natural resources, provide high-quality open space amenities, and reduce the ecological impact of new development. 

Over 170 communities in New Hampshire permit some form of this development today. Cluster housing laws are also known as “open space development” and “conservation development” laws. In its most common form, this method more closely groups homes within a subdivision by reducing the zoning codes’ dimensional requirements for new homes (such as minimum lot size). Cluster housing may also have different infrastructure requirements under a subdivision bylaw and may include a residential density bonus for open space protection. Cluster housing is typically given as an option for developers through a Conditional Use Permit (or other discretionary) process.

How can it help?

Cluster developments can…

  • Provide flexibility to both planning boards and developers for handling unique site characteristics, such as steep slopes, wetlands, and wildlife corridors.
  • Facilitate the preservation of large tracts of open space, protecting farmland, natural features, and key resources like aquifers.
  • Create smaller subdivision lots, which can be more affordable.
  • Reduce the footprint of new development, minimizing impervious surface and site grading.
  • Reduce the cost of construction and maintenance of infrastructure. Savings can be passed on to residents.
  • Reduce utility costs for residents.
  • Protect important views and vistas for the community.
  • Improve stormwater management.
  • Provide outdoor recreation opportunities, especially for seniors and young families living on site.
  • Increase overall supply of housing, especially smaller and less expensive housing types.

Getting Started

  1. Recognize and promote cluster housing’s impact on common master plan goals, such as open space preservation, natural resource management, and increased housing options.
  2. If undertaking a master plan, include cluster housing as a recommendation.
  3. Identify sites or areas of town appropriate for cluster development:
    1. Identify important natural or agricultural resources, especially those at the margins of recent development.
    2. Catalog parcels that include or are adjacent to those resources, noting those that are not already built out and may be likely to be developed.
  4. Build public awareness of preservation needs and alternative development options like cluster. 
    1. Use public forums, outreach to local boards and committees, and other engagement methods to grow awareness. 
    2. Use visuals to illustrate what cluster development is like.
  5. Craft an ordinance to allow for cluster housing in the identified areas. If you already have a cluster housing ordinance, craft an update to ensure its requirements are aligned with current needs and desires.
    1. The ordinance will need to consider the density of cluster housing units in terms of the whole site as well as on subdivided lots.
    2. The ordinance will need to consider dimensional regulations applying to the whole site, as well as the subdivided lots.
    3. Subdivision regulations will need to be updated to reflect and implement the zoning.
  6. Promote the cluster housing option to the owners of identified parcels, locally and regionally active housing developers.
  7. If possible, create opportunities for pre-proposal consultations between landowners, developers, and planning staff on cluster development designs and opportunities.
Clustered homes overlooking a working farm in Nubanusit Neighborhood and Farm in Peterborough. (Clive Russ via Harvard Magazine)

Considerations

  • Make cluster housing an allowed use by right. Conditional Use Permits and vague regulations can make the process unpredictable, which will discourage developers from choosing this option. Consider making cluster development mandatory for environmentally sensitive areas.
  • Ensure application procedures are not overly burdensome, especially compared to conventional development.
  • The method for determining housing density should be relatively simple and should not require a near-full design of a conventional subdivision to determine yield. Ensure any density formula is easily understood.
  • Incorporate basic design standards into the ordinance to better achieve the aesthetics desired in your community, while keeping the ordinance flexible enough to address unique site conditions. Rigid dimensional requirements, such as requiring large perimeter buffers may not work for every parcel.
  • If open spaces are provided to the public, try to provide public access separate from residents’ access.
  • Try to connect cluster development open spaces to existing open space resources and/or other cluster developments. This will expand the area of undeveloped contiguous land, which can create better recreational opportunities and ecosystem supports.
  • Consider requiring a design-oriented process, in which developers first design open space based on clear criteria, then site houses, roads, trails, and finally lot lines.

State Law

Case Studies

  • Nubanusit Neighborhood and Farm, Peterborough, NH
  • Terrell Farm, Nashua, NH
  • Brandywine at Thornbury, PA
    • Read more

Resources

Related Tools

A diagram of an idealized age-friendly neighborhood. The neighborhood includes a mix of housing types, including detached single-family homes of various sizes, mixed-use buildings, and a cottage court. The diagram includes the following labels pointing to aspects of the drawing: "Nearby retail, community center, and open space;" "Diverse housing options, including apartments and starter homes;" "Single-story housing layouts with shared amenities;" "Sidewalks and other accessible infrastructure;" and "Accessory dwelling units for multi-generational households."
Age Friendly Neighborhoods
A drawing of a plot of land. Most of the land is shown in green and planted with trees, with two small houses. It is labeled "Sending Zone: Land owners sell development permissions to preserve open space/agriculture." A smaller area is grayed out and shows many buildings. It is labeled "Receiving Zone: Land owners buy development permissions to increase allowed density."
Transfer of Development Rights (TDR)
A diagram of a parcel of land. On the top is a mix of one- to three-story buildings, many with an apparent mix of uses, sitting along the intersection of two roads. This is labeled "Mix of uses using traditional village design." Lines at the edges of this area point draw down, showing this area is at the center of a larger area shown in dark green and apparently undeveloped. It is labeled "80% of rural and conserved in VPA."
Village Plan Alternative (VPA)
A diagram of a single-family subdivision with twelve homes. Eight homes in red are labeled "Base Market-Rate Units." Two homes in yellow are labeled "Affordable Units." Two homes in blue are labeled "Bonus Market-Rate Units."
Inclusionary Zoning
A diagram showing the front facades of housing types and given labels: small single-family, townhomes (attached single-family), cottage court (grouped small single-family), duplex, stacked duplex, triplex, stacked triplex, four-plex, six-pack, courtyard apartments.
Missing Middle Housing Types
A subdivision of eight single-family homes surrounding a central green. The plot of land is labeled "Site plan that allows for community septic, prioritizing shared open space." Underground pipes lead from each home into a large underground box labeled "Joint septic tank." A pipe leads from that box into a smaller underground box labeled "Pre-treatment system." A pipe extends from that box and branches into many pipes with holes in them under a green area labeled "Community open space that doubles as a leach field."
Wastewater System Alternatives