In-law units are just a fraction of the homes in Kenny Lehtonen’s roster. The New Ipswich contractor completes just one or two of them each year, compared to the roughly two dozen single-family houses.
Lately, though, he’s been thinking about expanding that arm of his business. As in-law apartments — sometimes called granny flats or by their official name, accessory dwelling units — become more popular, Lehtonen thinks there’s a market for the tiny backyard homes.
He plans to start advertising them more as a core product of his family business, San Ken Homes. They’re easier to build, Lehtonen said, now that state law has cleared the way. Until last summer, any free-standing accessory dwelling unit required a variance from local zoning boards.
“It used to be one of those things where it was a little bit more challenging, especially in some towns, to get it accepted, so we kind of did it specifically just on an as-needed basis,” Lehtonen said. “Now, we’re starting to kind of change our business model a little bit to have it more of an advertised offering so that we can do more of them.”
While tiny homes won’t add units to the market en masse, they’re heralded by lawmakers and affordable housing advocates alike as a way to create more spaces to live while preserving New Hampshire’s rural character or, as Lehtonen put it, “without chewing up more land.”
Whether the new law will bring a wave of new housing to the region remains uncertain.
Numbers paint an unclear picture
The Ledger-Transcript reached out to 16 towns in the Monadnock area to analyze whether accessory dwelling units were growing in popularity after the new law went into effect on July 1.
Among the towns that responded, no clear picture emerged. A select few saw marginal increases. Some towns held steady; others had none at all.
In Peterborough, which has long allowed these structures and did not need to update its zoning ordinance to comply with state law, in-law apartments have been fairly common for years now. Over the past four years, the town has received 10 permit applications, according to Danica Miller, the town planner.
Miller hosted an “ADU Tour” last year, showcasing some that have been built in town for curious housing advocates and homeowners. Many are used among family members, Miller said then, or rented out for extra income.
Greenfield had just one permit application in 2025, down from four in the previous year, though building inspector Mike Borden can’t quite put his finger on why.
Greenfield was ahead of the curve, authorizing up to three detached residences on a property in addition to the main home. That update passed a few years ago, Borden said, to open the door to “family compounds.” No one has taken the town up on that yet; there are no lots with more than one detached in-law apartment, he said.
When state law first legitimized accessory dwelling units and allowed them as attachments to the main home, Borden recalled that multiple people jumped on the trend. Extending a current building is often easier and more economical than building a new one with utility hookups.
“I don’t hear a lot of buzz about it,” Borden said. “I mean, it certainly is practical but, you know, housing is expensive right now.”
Hancock hasn’t had any permit applications since 2023, despite receiving five over the three years prior. Sharon has not had any applications in the past three years.
In other towns, however, like New Ipswich and Lyndeborough, they may be on the rise. Three people applied for building permits in Lyndeborough, where voters were ahead of state law and authorized detached units in 2024.
The town further expanded its zoning ordinance by a petition warrant article this year, said building inspector Leo Trudeau.
“Now in Lyndeborough you can have two accessory dwelling units per single-family residential lot, which is more than the state mandates,” Trudeau said. “We do have an increase in interest in people wanting to do it, and it’s a good idea.”
Six were received in New Ipswich last year. That’s up from just one in 2024 and two in 2023.
Lehtonen suspects the growth in his town might be driven by its demographics, as New Ipswich is home to many who work in the building trades. It’s even cheaper for them to do the work themselves rather than hire someone else.
The town also has many sprawling families who stay local but face financial pressures, like high housing costs. At the end of the day, Lehtonen said, it’s a “function of economics.”
“There’s a lot of large families in New Ipswich that are probably just trying to make more housing units for friends or family members that want to stay in town, and there’s just no rentals available,” he said. “People that are growing up and getting married and wanting a place of their own, there’s just very little for them to choose from in town.”
Lehtonen is one of them. When he found his “forever house” a few years ago, he put in a foundation for a detached garage and ran plumbing, water and electric lines to that part of his property with the intention of transforming it into a living space down the line.
“I can easily just finish that off into an apartment,” he said. “I kind of already have plans in place, personally, to implement one on my own house when the time’s appropriate. Everything’s kind of pre-planned there.”
‘Age in place’
Several town offices said in-law apartments are typically used as just that: for in-laws. Some families are already taking advantage of the new state law, building tiny homes in their backyard for loved ones — oftentimes an aging parent.
The New Hampshire chapter of the American Association of Retired Persons lobbied hard for the state law for that very reason. More than a quarter of New Hampshire’s population — over 368,000 people — is age 60 or older, according to the 2025 Healthy Aging Data Report.
Michael Padmore, an AARP lobbyist, said the top thing they hear from the organization’s members is a desire to age in place, living independently in their own homes rather than at assisted care facilities.
Many older adults are looking to downsize to more manageable homes, Padmore said, and granny flats fit the bill as small, single-story units that allow seniors to live close to their families.
“When there are opportunities for folks to care for their loved ones in the same home or in the same property, it just makes that so much more viable,” Padmore said. “It’s not just more viable and better for the caregiver, but obviously that person who’s getting that care is just getting better care, because it’s just easier for everybody.”
Not every in-law apartment will stay an in-law apartment, however. Trudeau noted that even an accessory dwelling unit built for an aging parent today might turn into a rental 20 years down the line. As communities and populations shift, the use of these structures could too, he said.
“Eventually, they’re going to end up being rented out because nobody lives forever,” Trudeau said. “And then, here are these ADUs on a property, and why not rent it out? … There’s certainly a need for housing everywhere around here.”
