Portsmouth, New Hampshire

Portsmouth, NH Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 8/10

Last Updated: 8.28.2024

Image Source: Meredith NH

What You Need To Know

Portsmouth has create an easy to follow flowchart and process for homeowners who are interested in ADUs. Minimal requirements allow for flexibility in building ADUs in Portsmouth.

Type of ADU Permit Required

Requires Planning Department approval process. Once approved, submit for a building permit.

ADU Rules

  • 750 sq. ft max gross living area entirely within a single-family dwelling or 600 sq. ft. gross living area in a detached accessory building that complies with dimensional standards in certain zone districts.

  • Same ownership.

  • 1 parking space is required.

  • If connected, an interior door is required.

Accessory Dwelling Unit Application Instructions

Create an ADU in Portsmouth Flowchart

Resources:

https://www.cityofportsmouth.com/planportsmouth/accessory-dwelling-units-adu

Attached ADU, Convert Existing Space, Detatched ADUDeanna DuffeyNew Hampshiure, Friendliness Rating 8/10, Portsmouth