Supporters of accessory dwelling units, also known as “in-law units,” are cautiously optimistic that legislation will pass this spring that would make it easier to build apartment-like additions to single-family homes over the objections of local zoning boards. 

HB 1291, which was overwhelmingly passed by the New Hampshire House of Representatives in April, is currently before the New Hampshire Senate, which held a hearing earlier this month on the bill and as of publication time planned to hold another hearing on May 14 in Concord. 

The legislation is described by backers as a necessary update to the 2017 law that initially allowed construction of ADUs in New Hampshire – an update that effectively would override restrictions slapped on proposed ADU projects by unenthusiastic local zoning and planning boards. 

“There are so many things towns are requiring that it’s become de facto blocking of ADUs,” said Rep. Ellen Read, D-Newmarket, sponsor of HB 1291. “There are many unnecessary restrictions.” 

Among other things, the new bill would allow both attached and detached ADUs, instead of the exclusively attached units that many local governments currently require. It would also ease ADU size limits imposed by local boards, allowing larger units up to a maximum of 1,000 square feet. 

The bill would also allow most single-family homeowners to build up to two accessory dwelling units by right, effectively forbidding local government from requiring only one unit per property. 

A Senate amendment has been attached to HB1291 that would remove the second-dwelling provision from the legislation. 

ADU supporters have also complained that local boards have required excessive parking requirements for ADU and other housing projects. A companion bill passed last month by the House, HB 1400, would limit the number of parking spaces that a town or city could require to one parking spot per unit.  

Current Law is ‘Quite Weak’ 

Supporters of ADUs say the legal update to the 2017 law is necessary if ADUs are going to live up to their promise of helping ease the housing shortage in New Hampshire. 

They certainly haven’t lived up to expectations so far. 

When the 2017 ADU law was first passed, some studies predicted it could lead to construction of tens of thousands of new units in New Hampshire. 

But Ben Frost, deputy executive director and chief legal officer at New Hampshire Housing Finance Authority, known simply as New Hampshire Housing, said that “maybe 1,000” ADUs have been built since 2017.  

And that number could well be lower. The problem is that there’s no central authority keeping track of ADU construction in New Hampshire, so it’s partly a guessing game based on anecdotal evidence, said Frost. 

Though there are no hard stats on new ADUs in New Hampshire, Frost said there’s little doubt the number of new units is disappointing. “It’s a lot less than what we should be building,” he said. 

Frost added he has “no doubt” that passage of HB 1291 will spur more ADU construction in the state – and not only because it overrides specific restrictions slapped on projects by local boards.  

He said the wording of the bill could also lead to fewer zoning-variance public hearings for ADU projects – and that could encourage more homeowners to apply for ADU permits. “Some people are just not up for going through a public hearing process,” he said. 

HB 1291 Will ‘Help a Lot’ 

Emily Hamilton, a housing economist at George Mason University, has studied ADU ordinances in 29 communities in New Hampshire with populations of more than 10,000, and found a slew of local restrictions, from parking restrictions to owner-occupant requirements. Most towns also required doorways that connect ADUs to a main house. 

The net result: Fewer new ADUs than one might expect in New Hampshire, she said. 

As part of her study, Hamilton viewed data from eight communities that keep track of ADU building permits – Nashua, Derry, Dover, Hudson, Merrimack, Portsmouth, Hampton and Claremont – and found more than 200 permitted ADU projects between 2017 and 2021.  

That’s “not a bad” figure on the surface of it, but it isn’t all that impressive when you consider it’s spread out over four years, she said. 

The bottom line: New Hampshire’s current ADU law is “quite weak” compared to ADU statutes in other states – and reforms are definitely needed if the state’s ADU goals are to be met, Hamilton said.  

Regarding HB 1291, Hamilton said “it will help a lot.” 

‘A Lot of Interest in ADU’ Construction 

Jessica Stevenson is one of those hoping the legislation, if passed, will lead to a surge in ADU projects. 

Stevenson, a real estate broker, and her husband, Mark Stevenson, who works in construction, recently launched a local franchise of Anchored Tiny Homes, a custom-ADU construction company based in California. Stevenson’s franchise district covers most of southern New Hampshire, stretching from Nashua to Concord to Portsmouth. 

“We’re finding there’s a lot of interest in ADUs,” said Stevenson, whose franchise opened last month. “We’ve signed a number of contracts already.” 

The cost of an ADU, as designed and developed by Anchored Tiny Homes, can range from about $90,000 for a studio-like unit to $240,000 for a large two-bedroom unit, she said. 

Help is needed to overcome the slew of restrictions that local governments can impose on projects, said Hamilton. 

“It can be frustrating. Every town does things different. They put up their own rules and regulations. We help our clients navigate the process.” 

Matt Mayberry, executive director of the New Hampshire Home Builders Association, said many contractors are chomping at the bit to build more ADUs.  

ADUs not only benefit the building industry and help ease the housing crisis in New Hampshire, they also help prevent suburban sprawl by limiting construction to already developed properties, he said.  

“We’re trying to get more obtainable, affordable housing in this state,” he said. “ADUs can help.”