| Max size | 950 sq ftconfirmed with the town |
|---|---|
| Min size | No town minimum750 sq ft floor protects you |
| Bedrooms | Up to 2confirmed with the town |
| Type | Attached or detachedby right in R, R-1, R-2 |
| Parking | No specific number of spots but highlighted…confirmed with the town |
| Owner-occupancy | Requiredin either the ADU or the primary home |
| Short-term rental | Not stated |
| Utility connection | Tie into the existing electrical connection or choose a separate metersame statewide |
The July 2025 state law (RSA 674:71–73) overrides local ordinance language that conflicts with it — even language a town still has posted. Here's what that means in Auburn:
Under state law, the on-site-vs-off-site choice for the ADU's extra parking space is yours to make, not the Planning Board's to approve. Auburn's general parking rule still says you can only park an ADU space off-site if the Planning Board agrees on-site parking is impractical — but state law overrides that gatekeeping.
Auburn can ask you to screen or landscape a detached ADU so it doesn't dominate the view from the street — but whether that 'visually subordinate' standard goes further than what an ordinary detached garage or accessory structure would face is genuinely ambiguous. Worth an attorney's read before assuming the town can enforce it as written.
C-2 doesn't broadly permit new single-family detached dwellings as a matter of right — the ordinance only allows additions/expansions to single-family homes that were already lawfully there as of March 10, 2009 (§4.07(8)). Because C-2 doesn't generally 'permit' single-family dwellings, requiring a special exception for an ADU there is probably defensible, but it's close enough to the state-law line to flag rather than wave through.
CONFIRMED WITH THE TOWN (July 22, 2026) — ADUs allowed: 1; maximum size 950 sq ft; up to 2 bedrooms; impact fees: None yet; parking: No specific number of spots but highlighted through the zoning ordiance the ADU must have adequate parking on the property to accommodate an accessory dwelling unit; setbacks: Largest residential zone in Auburn is R1 and R2 - setbacks there are 50' front and rear, 30' side. Town contact: Mark Ekberg - Building Inspector / Code Enforcement Officer.
Where a detached accessory dwelling unit may create visual impacts or reduce privacy for abutting residential properties, the Planning Board or Code Enforcement Officer may require screening, vegetation retention, fencing, or other mitigation
Attached accessory dwelling units shall have either an independent means of ingress and egress or ingress and egress through a common space shared with the principal dwelling. The accessory dwelling unit shall have a door with direct access to the exterior, or common space to hallway or exterior door. Has to have interconnected smokes/co
Auburn's ADU rules live in §2.02(28) of the town's 'Zoning Ordinance 2026' (cover page shows a March 2026 revision, post-dating the July 1, 2025 effective date of the state ADU law). Compared to Auburn's own pre-2026 regime — which was attached-only, special-exception, and capped at 750 sq ft — the current ordinance is a near-total rewrite in the homeowner's favor and closely tracks the state law: ADUs are now a By-Right Permitted Use (no special exception, no board hearing) in every district that principally allows single-family detached dwellings (R, R-1, R-2); attached AND detached ADUs are both allowed, including converting an existing detached garage even if it's nonconforming on setbacks or lot coverage; size is capped at 950 sq ft with an effective 750 sq ft floor (matching the state law's numbers exactly); bedrooms are capped at two (not one); owner-occupancy is required but the ordinance doesn't dictate which unit; and only a building permit is needed. Two areas still favor the homeowner beyond what Auburn's ordinance states outright: (1) the town's general parking article only allows off-site ADU parking when the Planning Board agrees on-site parking is impractical, whereas state law gives that on-site/off-site choice to the property owner directly — state law controls; and (2) a 'visually subordinate' siting/screening standard for detached ADUs could, depending on how it's enforced, read as more design scrutiny than an ordinary accessory structure would get — a call for a land-use attorney, not a clear violation. A third, lower-confidence item: the zoning matrix marks ADUs as a special exception (not by-right) in the C-2 commercial district, but C-2 doesn't broadly permit new single-family homes either, so this is more a watch-item than a clear conflict. See conflicts for full citations and resolved_by_town for what Auburn already fixed since 2024.
Get a free personalized report for your address in Auburn — including where the 2025 law works in your favor.
Get My Free Auburn ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Auburn's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — Auburn allows one accessory dwelling unit (attached or detached) by right in the Rural, R-1, and R-2 districts. Under RSA 674:72 (as amended effective July 1, 2025), one accessory dwelling unit — attached or detached — is allowed by right on single-family lots statewide.
950 sq ft — confirmed with the town. State law doesn't let any town cap ADU size below 750 sq ft.
Attached or detached (by right in R, R-1, R-2). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
No specific number of spots but highlighted… — confirmed with the town. State law caps what any town can require at one additional space, located on- or off-site at the owner's choice.
Required — in either the ADU or the primary home. Where owner-occupancy is required, state law lets the owner choose which unit to live in.