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Remember the “mother-in-law suite” or “granny flat”? These small, separate living spaces tucked behind a main house were once common in American neighborhoods. After World War II, they popped up across the country, offering families a way to keep loved ones close while giving them independence. However, over time, zoning laws made it increasingly difficult to build them, and they gradually faded from view.
Now, they’re making a comeback — and they’re called Accessory Dwelling Units, or ADUs. An ADU is a second unit built on the same lot as or within a single-family house. It might be a converted garage, a basement apartment, or a tiny house in the backyard.
The vast majority of people want to remain in their home or community as they age. For that to be reality, communities need to include a range of housing options that can fit people’s needs as they age. ADUs are one such option.
New Hampshire recently made significant updates to its state ADU laws that went into effect on July 1, 2025, expanding opportunities for Granite State homeowners and families to build ADUs more easily, especially as housing costs increase, and families seek better ways to care for aging relatives.
Here's a summary of the key changes and their implications for New Hampshire residents:
These changes remove many of the previous barriers that made ADU construction difficult or expensive, especially for families looking to house aging parents, adult children, or caregivers.
For older adults, ADUs offer the opportunity to age in place — to stay in the neighborhoods they know and love, even as their needs evolve.
Specifically, these changes make it easier for Granite Staters to:
Ready to explore ADUs for your family?
AARP has free tools to help you get started:
As more communities adopt ADUs, we may see a resurgence of the kind of multigenerational living that was once common in America. And that’s good news for families, for neighborhoods, and for anyone who believes that home should be a place where people of all ages can thrive. So, whether you’re planning for a loved one’s future or your own, ADUs can help you stay close, stay safe, and stay home.