New Hampshire Zoning Atlas

A collaborative effort led by Saint Anselm College

The New Hampshire Zoning Atlas is a database and interactive online map cataloguing and portraying zoning district-level land use regulations affecting housing construction across the entire land area of the state. The data are valid as of June 1, 2024 and represent the zoning and other land use regulations that local governments have adopted in their own ordinances, and in some cases, the ways in which state law interacts with those provisions. The data are available to download so that users can reproduce their own maps, analyze the data statistically, and integrate the datasets with information from other sources or states. Below, the background and basic methodology for the Atlas is presented, followed by some of the major findings illustrated with static maps, and finally an interactive version of the Atlas for deeper exploration is available within this summary. A link to the full NH Zoning Atlas is also provided, as well as a tutorial on how to use the NH Zoning Atlas.

Background

Map depicting the 269 jurisdictions in the State of New Hampshire — The 269 jurisdictions in the State of New Hampshire

New Hampshire has 228 jurisdictions with independent zoning authority. 215 of these jurisdictions are municipalities, but 10 are submunicipal and village governments, and one (Coös) is a county with zoning authority for 23 unincorporated areas within its territory. There are also two unincorporated places without zoning. The goal of the NH Zoning Atlas is to compile the regulations of all of these authorities into a comprehensive statewide dataset. In total, there are 269 jurisdictions in the dataset: every municipal and submunicipal zoning authority mentioned above, plus 19 towns without zoning.

There are two datasets. The first, a Google spreadsheet, contains the "raw data" found in local ordinances, including textual descriptions of complex rules that could not be summarized with a single number without some loss of information, and covers all zoning districts in the state, including unmapped districts. The second dataset, available in comma-separated values (csv) format, covers only mapped districts, includes state legal provisions that in some cases override local zoning rules inconsistent with state law, and interprets complex rules as numerical codes suitable for statistical analysis and filtering operations in the map. It also removes base districts that are wholly contained within overlay districts to avoid double-counting. The second dataset links up to the attribute table in the ArcGIS feature class for the state. These datasets are accessible here .

Data Available in the New Hampshire Zoning Atlas 1- through 5+- Family Regulations • Minimum Lot Size • Setbacks (front, side, rear) • Minimum Frontage • Maximum Lot Coverage (buildings and/or impervious surfaces) • Minimum Parking • Maximum Height • Floor Area Ratio • Minimum Unit Size • Maximum Density (2 through 5+ family) Affordable Housing Treatment – all the above plus • Water and/or Sewer requirement • Connection or Proximity to Public Transit requirement • Maximum Bedrooms per Unit • Maximum Units per Building • Minimum Buffer from other Residential Accessory Dwelling Unit (ADU) Treatment • Employer or Family Occupancy requirement • Renter Occupancy prohibition • Owner Occupancy requirement • Elderly Housing requirement • Additional Minimum Lot Area • Additional Minimum Parking • Attachment requirement • Maximum Size (percent and/or square feet) • Maximum Bedrooms Manufactured Housing Zoning (parks only, lots only, both or prohibited) Primary Nonresidential Type allowed (if applicable) Type of Discretionary Permit Required Additional District Notes — Data available in the Google Sheet, csv, GIS files and embedded within the interactive online Zoning Atlas

Methodology

Throughout the summer of 2022 zoning codes from across the state were collected and synthesized to create a single spreadsheet cataloging every single zoning district (base and overlay). This spreadsheet contains basic information such as the name and abbreviation for each district, whether the district is an overlay, and the primary purpose of the district (residential, mixed use, or non-residential). In addition to this basic information multiple characteristics were coded into the spreadsheet regarding treatment of different housing types, dimensional requirements, parking requirements, affordable or elderly housing requirements, and other considerations. During the summer and fall of 2023 amendments to zoning codes, which were approved between June 1, 2022 and June 1, 2023 were reviewed and the spreadsheet was updated to reflect the current regulations.

An old scanned image of a zoning map — An example of a map for which GIS data were unavailable and digitization was required.

Concurrent to the collating of the codes, geographic information systems (GIS) data was collected for each jurisdiction, where available. These GIS files, along with dozens newly created for this project by digitizing print versions of zoning maps, were merged into a single statewide GIS feature layer. This GIS layer was then joined with a modified version of the zoning attribute table. Finally areas considered to be non-developable due to permanent protection status or the presence of 10 or more contiguous acres of water and/or wetlands were clipped out of the statewide zoning layer. This resulting layer allows for the visualization and analysis of the "buildable" areas , which is approximately 61% of the state.

For a more detailed overview of the methodology refer to the The New Hampshire Zoning Atlas paper found on the NH Zoning Atlas home page , or linked here . The paper also details many findings from studying the NH Zoning Atlas, several of which are summarized below.

Statewide Findings

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As mentioned above, 39% of the state is considered non-buildable due to permanent protection status or large water and wetland areas. Of the buildable area, 46.3% is zoned for primarily residential uses. 50.3% is zoned for mixed-use (residential and commercial), while only 2.2% is zoned for primarily commercial or industrial use, while the remaining 1.2% is zoned exclusively for conservation or agriculture.

Single-family housing is allowed by right on 93% of New Hampshire's 3.6 million buildable acres. It is allowed by public hearing on a further 3% and is prohibited on only 4% of the buildable acreage.

Multi-family development is allowed in less districts than single-family, the least of which being 5+ -family homes. 5+-family is allowed by right (7.8%) or with a public hearing (41.5%) on 49.2% of the buildable area of the state. In an additional 4.8% of the buildable area 5+-family is permitted if restricted to affordable or elderly housing.

Looking closer at the data, it is hard to find land to build small homes or starter homes in an economically viable way. Most communities have prohibited single family homes on small lots (<1 ac,<200 ft frontage). Only 15.7% of the state’s buildable area allows for this type of development based on average soil and infrastructure conditions. This number could range between 12.5 to 19% depending on soil conditions and/or the availability of water and sewer infrastructure as several jurisdictions have a sliding scale of dimensional requirements based on site conditions.

Example of single-family homes on small lots.

Many of New Hampshire’s communities, including those close to job markets, also require larger lots for multifamily housing, thereby driving up the cost of these homes. Approximately 21% of the state's buildable area allow (7.6% by Right and 13.5% Public Hearing) for 5+-family homes on smaller lots (<2.5 acres, 2 units/acre), with an additional 1% for affordable or elderly restricted housing.

Example of a 5+ unit building on a small lot.

Under NH law communities are required to allow attached accessory dwelling units (ADUs), but the approval process in many places is time-consuming and expensive. In some communities the requirements for additional parking limits ADU development. For example, on 46.6% of the buildable area attached ADUs are allowed by right with under two minimum parking spaces. This is an increase since the Atlas was first introduced, when in 2022 only 42.3% of the buildable area allowed attached ADUs with less than two parking spaces.

NH law requires municipalities to allow manufactured housing (mobile homes) in at least one of three different ways: on individual lots, in manufactured housing parks, or in manufactured housing subdivisions. For purposes of this analysis, the Zoning Atlas combines parks and subdivisions as “parks”. The treatment of manufactured housing varies across the state. Within the buildable areas of the state manufactured housing is permitted as follows:

32% Allowed in both manufactured housing parks and individual lots
48% Allowed on individual lots only
6% Allowed in manufactured housing parks only
14% Prohibited

Taking a closer look at where manufactured housing is both permitted and likely to be affordable based on small minimum lot sizes or permitted within manufactured home parks, we see the area for manufactured housing statewide drops from 85% to 40%. Small lots are defined as having minimum required lot size of less than one acre and less than 200 feet of frontage. Within the buildable areas of the state manufactured housing that is likely to be affordable is permitted as follows:

10.2% Allowed in both manufactured housing parks and small individual lots
2.8% Allowed on small individual lots
27.7% Allowed in manufactured housing parks only
59.3% Prohibited

Additional Findings

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There are numerous additional statewide and local findings detailed in the previously referenced paper. Several of those findings are included here for those that want to explore them by using the arrow at right to advance through them. Continue scrolling at anytime to continue to the next section.

Previously we discussed the lack of available buildable area zoned for small-lot single or 5+ family development, even with water and sewer. The same is true for 2-4 family treatments as well

Like with single-family, most communities have prohibited 2-family homes on small lots (<1 ac,2 unit/acre). There is actually less available area for this type development where only 10.7% of the state’s buildable area allows for this type of development based on average soil and infrastructure conditions. Even under "ideal" conditions with good soils and/or available water and sewer only 14.2% of the buildable area is available for 2-family small lot development.

3-family homes on small lots (<1.5 ac,2 unit/acre) are similarly restricted. 15% of the state’s buildable area allows for this type of development based on average soil and infrastructure conditions, with an additional 1% available if the multifamily is for elderly or affordable housing. Under "ideal" conditions with good soils and/or available water and sewer the available area increases to 18% of the buildable area for market-rate 3-family development.

4-family homes on small lots (<2 ac,2 unit/acre) are similar to other multifamily with 18% of the state’s buildable area allowing for this type of development based on average soil and infrastructure conditions, with an additional 1% available if the multifamily is for elderly or affordable housing. Under "ideal" conditions with good soils and/or available water and sewer the available area increases to 20% of the buildable area for market-rate 4-family development.

As previously noted 5+-family development of small lots is allowed on 21% of the state's buildable area under average conditions. Under "ideal" conditions with good soils and/or available water and sewer the available area increases to 23% of the buildable area for market-rate 5+-family development, with an additional 1% available if the multifamily is for elderly or affordable housing.

In addition to lot size restrictions, parking requirements can often be a financially limiting factor for multifamily development. For example, nearly half of the buildable area (46%) where 5+-family is permitted requires two or more parking spaces per one-bedroom or studio unit.

Further Analysis: Manchester

While the statewide analysis provides a broad overview of the nature of housing regulations across New Hampshire, we wanted to examine regulations at a regional level. We chose to focus on the state's largest metropolitan area: the City of Manchester and the adjacent seven towns of Auburn, Bedford, Goffstown, Hooksett, Litchfield, Londonderry and Merrimack. Specifically we looked at available parcels for development based on both the zoning regulations and the available build-out potential of the over 70,000 parcels within the eight community region. Note this analysis was completed using the 2022 Atlas data.

Based on zoning, single-family housing is permitted in approximately 89% of the region's buildable area, comparable to the 90% permitted statewide .

Map of the City of Manchester and adjacent towns, coded to show zoning districts where single-family housing is allowed. Map also depicts non-developable land and where development is prohibited.

When we factor in existing development and only look at parcels that are vacant or have additional development potential the area available for new single-family homes drops to 33% of the region's buildable area.

If we look further at only small-lot (<1 acre, <200 ft frontage) single-family homes, 21% of the buildable area permits small-lot single-family homes.

But then when we look at only vacant or underdeveloped lots the buildable area available for small-lot single-family homes decreases to only 7.8%.

For more details on the methodology and results of the Manchester area analysis refer to this summary paper .

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For those that want to explore additional findings for the Manchester area, use the arrow at right to advance through additional maps. Continue scrolling at anytime to continue to the next section.

Approximately 19% of the area is available for Duplex (2-Family) development based on existing development and land use constraints, with an additional 2% available with restrictions.

When looking at small lot development (<1 acre, < 200 feet frontage, and greater than 2 units per acre density) only 1.9% of the area is available for Duplex (2-Family) development based on existing development and land use constraints.

Approximately 5.3% of the area is available for 3-Family development based on existing development and land use constraints, with an additional 9.4% available with restrictions.

When looking at small lot development (<1 .5 acres, < 250 feet frontage, and greater than 2 units per acre density) only 2.8% of the area is available for 3-Family development based on existing development and land use constraints. An additional 9.4% is available with restrictions

Approximately 5.1% of the area is available for 4-Family development based on existing development and land use constraints, with an additional 8.2% available with restrictions.

When looking at small lot development (<2 acres, < 300 feet frontage, and greater than 2 units per acre density) only 2.8% of the area is available for 4-Family development based on existing development and land use constraints. An additional 7.1% is available with restrictions

Approximately 5.3% of the area is available for 5-Family development based on existing development and land use constraints, with an additional 6.8% available with restrictions.

When looking at small lot development (<2.5 acres, < 300 feet frontage, and greater than 2 units per acre density) only 3.7% of the area is available for 5-Family development based on existing development and land use constraints. An additional 6.8% is available with restrictions

Interactive Atlas

This map shows the zoning districts, less non-buildable areas, for the entire State of New Hampshire. Clicking on the map will bring up information for each jurisdiction and the underlying zoning district. Use the arrows in the corner of the pop-up window to cycle between the jurisdiction data and the zoning district(s) data. For the ability to filter the data shown on the map you can view the full NH Zoning Atlas interactive mapping application here .

A brief tutorial on using the NH Zoning Atlas is available here .

NH Zoning Atlas interactive map

Conclusions and Next Steps

Data collected for the NH Zoning Atlas suggest that there is much that we can do to adjust our zoning and help our communities be more welcoming to a modest increase in housing. Changes to zoning will help communities remain vibrant and assist our state in attracting and retaining young people, growing families, aging seniors, and a strong workforce for our economy.

The New Hampshire Zoning Atlas does not take a position in the debate between those who advocate for local control, and those who argue for stronger state limits on local governance. We simply encourage policy-makers at the local and state levels to discuss possible changes in zoning, both small and large, that can help ease the housing shortage and strengthen our communities. How those changes take place is for others to decide.

A variety of changes can and should be discussed, including appropriate reductions in minimum lot sizes for single-family and multi-family housing, front setback requirements, and parking requirements, perhaps especially for ADU’s.

At present, the plan is to update the atlas annually with data valid as of June 1st of each year, and to maintain a consistent time series for research purposes. The New Hampshire Zoning Atlas will remain an integral part of the National Zoning Atlas and will continue to provide critical information on the formal legal treatment of housing development in the Granite State. Visit the NH Zoning Atlas page ( NHZoningAtlas.org ) for the most up-to-date information.