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ADU Rules in Strafford County, New Hampshire

6 towns covered · Reconciled with the 2025 state law · Last reviewed 2026-09-10
The short answer
Every town in Strafford County must allow one ADU — attached or detached — by right on single-family lots.

That's the statewide floor under RSA 674:72, effective July 1, 2025. What differs town to town is the details: size caps, parking, owner-occupancy, and how much of each town's posted ordinance the state law now overrides. Pick your town below for the plain-English breakdown.

Strafford County towns

Barrington

Barrington's ordinance predates the 2025 state law overhaul, so several provisions — including a mandatory shared electric meter and an interior…

Read the full Barrington ADU guide →
Dover

Dover's newest published ADU paperwork is still dated 2021 and shows no update for the state's July 2025 ADU law — it caps units at 800 sq ft, only…

Read the full Dover ADU guide →
Lee

Lee rewrote its ADU rules at the March 10, 2026 town election and did a genuinely good job — detached units are in, the size cap is 1,000 sq ft (more…

Read the full Lee ADU guide →
Madbury

Madbury rewrote its ADU section in March 2025 — but that was four months BEFORE the new state law took effect, and the town spent its entire 2026…

Read the full Madbury ADU guide →
Rochester

Rochester's posted ADU rules (last amended 2017-2019) still require a Zoning Board special exception for any DETACHED accessory apartment — but since…

Read the full Rochester ADU guide →
Strafford

Strafford's ADU ordinance dates to March 2017 and still requires a full ZBA special-exception hearing, gates detached units behind full 2-acre lot…

Read the full Strafford ADU guide →

Not sure what your lot allows?

Get a free personalized ADU report for your property in Strafford County.

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Learn the statewide law

Wherever a town's rules are stricter than the state floor, the state law controls. Read the full New Hampshire ADU law explainer →

Other counties

Rockingham CountyHillsborough CountyMerrimack CountyBelknap CountyCarroll CountyGrafton County
This guide is an independent informational resource, not legal advice; confirm details with your town's planning department before you build.