Accessory Dwelling Units (ADU)

An “Accessory Dwelling Unit" (ADU) is a permanent residential dwelling unit that provides a complete independent living facility for one or more persons that is smaller in size, and accessory to, a primary single family residential dwelling on the same parcel of land. As a residential unit, an ADU provides the same residential provisions of living, sleeping, eating, cooking, and sanitation as are found in other residential dwellings.

This page is for homeowners and contractors who are interested in creating an Accessory Dwelling Unit (ADU) in the City of Portsmouth. The process to apply, design, permit and build an ADU will be described to assist a single-family property owner in assessing if and what type of ADU may be best for their property.

The purpose is to promote the design and construction of an ADU as a low-density, affordable housing option in a manner that is an appropriate residential infill development type aligned to the character of Portsmouth neighborhoods. 

The intent is to inform homeowners about ADUs, explanations about how an ADU may accommodate their lifestyle needs, and help them decide whether creating an ADU is right for them.