✓ ADUs Are Allowed by Right in New Hampshire
Instantly look up zoning rules, setbacks, and permit requirements for your specific town — translated from legal jargon into plain English.
Enter your address or town to see exactly what you can build on your property.
Click any town to see a plain-language breakdown of what you can build — no legal degree required.
New Hampshire's ADU laws changed significantly in 2025. We cut through the noise and give you exactly what you need to know about your property.
Enter your town. Our system pulls the most current zoning ordinance — including the 2025 state law changes that most town websites haven't clearly posted yet.
We translate complex legal language into clear, actionable information. See exactly what size ADU you can build, setback requirements, parking rules, and permit steps.
✓ Every town cross-checked line-by-line against the 2025 state law
Enter your contact info to unlock your personalized ADU breakdown — a detailed look at your town's rules and where the 2025 law works in your favor.
Stop guessing. Get a personalized report for your specific town — including its current rules, the 2025 law changes, and where the state now gives you more than the town's own website admits.
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Yes. House Bill 577 took effect July 1, 2025, significantly expanding ADU rights. Every single-family property in NH can now build a detached ADU by right — no special permits or conditional use approvals required. Many town websites haven't fully updated their zoning pages to reflect this, which is exactly why this guide exists.
An attached ADU shares a wall with your main home — think a finished basement apartment or an addition. A detached ADU is a completely separate structure on your property, like a backyard cottage or garage conversion. The 2025 law now requires both types to be allowed by right in New Hampshire.
Yes — and this is where it gets complicated. While state law sets the floor, municipalities can still impose reasonable conditions like setbacks, maximum square footage, owner-occupancy, and parking. Our town lookup shows you both the state baseline and your specific local rules side by side — including where the town's posted rules are now overridden by the 2025 law.
Costs vary based on size, type, and your town's requirements. Interior and attached conversions typically range from $80,000–$165,000. Detached new construction generally runs $150,000–$300,000+. Your report includes a cost range based on your town and goals.