Manchester ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Manchester, New Hampshire means pulling a building permit from the local authority that issues it. ArchPermit tracks 12 source-cited requirements (10 required, the rest conditional) for this jurisdiction. Submittals go through gTechna online portal (building) + Planning Board (CUP). These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in City of Manchester. Every item links to its authoritative source; items that vary are flagged to confirm locally.
Manchester currently requires a Conditional Use Permit (CUP) from the Planning Board BEFORE building permits; ADUs are allowed by CUP in all residential districts (R-S, R-1A, R-1B, R-2, R-3, R-SM). One ADU per single-family dwelling, only within the dwelling or its attached/detached garage; owner-occupancy required (common ownership, no condominium); ≤2 bedrooms; ≤750 sf gross floor area; +1 off-street parking per ADU bedroom. A Certificate of Occupancy AND a Certificate of Compliance are required before the ADU is recognized. ⚠️ NH RSA 674:71 to 73 (eff July 1 2025) requires municipalities to allow one attached + one detached ADU by-right with no permits other than building permits. Manchester's CUP requirement and garage-only/no-detached rule appear to predate / not yet reflect the state mandate; confirm with PCD whether the CUP step still applies.
- Abutter List (RSA 672:3)required
Names + mailing addresses of all abutting owners of record, for the CUP public hearing.
source · reviewed 2026-06-22 - Building Permit Application + Feerequired
Applied online via gTechna (or paper), reviewed for Building Code + Zoning Ordinance compliance.
source · reviewed 2026-06-22 - Certificate of Occupancy + Certificate of Compliancerequired
Both required before the ADU is City-recognized; cannot be granted without prior approval of all building permits + Housing Code conformance.
source · reviewed 2026-06-22 - Conditional Use Permit (CUP) Applicationrequiredverify locally
Planning Board CUP, signed by the owner, obtained before the building permit (currently required; NH RSA 674:71 to 73 may now bar requiring it; confirm with PCD).
source · reviewed 2026-06-22 - Copy of Deed + Tax Map + Property Cardrequired
A copy of the deed with lot description, plus the tax map and current property card.
source · reviewed 2026-06-22 - Electrical / Plumbing / Heating Permit Applicationsrequired
Separate trade permits by licensed trades; filled online but printed, signed, and mailed with fees (not accepted electronically).
source · reviewed 2026-06-22 - Floor Plans / Elevations (6 copies)required
Floor plans plus elevations (required for any new construction, including additions).
source · reviewed 2026-06-22 - Letter Addressing Article 12.05 + Architectural-Consistency Criteriarequired
Written narrative addressing the CUP decision criteria; the Board must find the exterior architecturally consistent with the primary residence.
source · reviewed 2026-06-22 - Means-of-Egress / Fire-Safety / Ventilation Compliancerequired
Two means of egress per unit; bedroom emergency egress; hardwired smoke + CO detectors; habitable-room window area ≥1/10 floor area; bathroom window ≥3 sf or mechanical ventilation.
source · reviewed 2026-06-22 - Plot / Site Plan (6 copies, to scale)required
Existing conditions + proposed changes: lot, building, parking, setbacks, driveways, streets, all setback information noted.
source · reviewed 2026-06-22 - Owner Affidavit (if owner ≠ applicant)conditional
A signed affidavit from the owner when the owner is not the applicant/agent.
source · reviewed 2026-06-22 - Wastewater / Septic Provisionconditional
If not on municipal sewer, the septic system must meet NH WSPCD requirements (RSA 485-A:38).
source · reviewed 2026-06-22
Manchester ADU permit questions
- Do I need a permit to build an ADU in Manchester?
- Yes. An accessory dwelling unit (ADU) in Manchester requires a building permit. ArchPermit tracks 12 cited requirements for this jurisdiction (10 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Manchester?
- Core required items include: Abutter List (RSA 672:3); Building Permit Application + Fee; Certificate of Occupancy + Certificate of Compliance; Conditional Use Permit (CUP) Application; Copy of Deed + Tax Map + Property Card; Electrical / Plumbing / Heating Permit Applications, plus 4 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Manchester?
- Manchester accepts permit submittals via gTechna online portal (building) + Planning Board (CUP). ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.