Kingston and Temple require four parking spaces when building a single-family residence.
Amherst mandates at least 25 acres for a five-family housing building, with each additional unit needing another five acres in one zoning district.
And a section of Hancock limits elderly housing to one bedroom per unit.
That patchwork of requirements may be found for 269 cities, towns and other jurisdictions in The New Hampshire Zoning Atlas going live online Tuesday at nhzoningatlas.org.
“Helping our communities to make better decisions about zoning in their own community vis-a-vis what’s happening in communities around them, that’s my No. 1 hope,” said Max Letona, executive director of the Center for Ethics in Society at Saint Anselm College, at a media briefing Monday.
The $100,000 project involved more than 20 people, including about 10 students, who read through more than 23,000 pages of zoning and subdivision regulations to create the interactive map, which can help people see where certain types of housing are allowed, down to a specific address.
“Here in response to the building booms of the 1970s and the 1980s, municipal governments throughout the state used their zoning power … to limit or outright prohibit any growth except for large-lot, single-family development, and we see the results of that today,” said Ben Frost, deputy executive director and chief legal officer at New Hampshire Housing, a project partner.
Among the findings:
• Most communities have prohibited single-family homes on small lots over most or all of their territory. Only 16% of buildable land is zoned for single-family homes on an acre of land or less.
“We see that small-lot single family is highly restricted in most of the state,” said Jason Sorens, senior research faculty for the American Institute for Economic Research, which helped in the project.
• More than half of the state’s zoning districts banned construction of any housing with five or more units.
• Seventy jurisdictions don’t allow two-family housing.
• Many communities, “including those close to job markets, require larger lots for multifamily housing, thereby driving up the cost of these homes and making them unaffordable to residents,” according to presentation documents.
Meanwhile, a parcel analysis of Manchester and seven surrounding towns shows how few single-family homes can be built on an acre of land or less.
Once existing development and land use restrictions are taken into account, only 7.8% of available land may be used for single-family homes on an acre or less.
Statewide, 39% of the land is considered non-buildable because permanent protection status or large water and wetland areas. Of the buildable area, 46.3% is zoned for primarily residential uses. Another 50.3% is zoned for mixed-use (residential and commercial), while only 2.2% is zoned for primarily commercial or industrial use. The other 1.2% is zoned exclusively for conservation or agriculture.
Frost said the Legislature tells municipalities they must do certain things, such as allowing accessory dwelling units or affordable housing projects, but it gives them leeway.
“Some municipalities will only do the bare minimum in response to what the Legislature tells them they should do, regardless of what the outcome might be,” Frost said.
New Hampshire needs 23,500 new housing units to meet its existing need, Frost said.
“We need to do more housing production, and that doesn’t mean any one community needs to be flooded with housing development, but we need modest increases in housing production throughout the state in each community,” Frost said.
“We also recognize that local zoning barriers do impede economic growth statewide,” Frost said.
Manchester developer Dick Anagnost, who will speak at Tuesday’s kickoff, said the zoning atlas will help fellow builders.
“This is the first time I’ve seen a repository for all the information for everyone in New Hampshire in one place,” Anagnost, the state’s largest developer of workforce housing, said in an interview.
Municipalities in the northern half “are less likely to have zoning to begin with, but if they do have zoning, they often allow five-family structures across the whole town” compared with southern areas, Sorens said.
“In general, they just are more tolerant of residential development, which is again a little bit ironic because those are places where you’re not going to get a lot of demand to build five-unit structures,” he said.
