Accessory Dwelling Units


The Basics

What is an Accessory Dwelling Unit?

An accessory dwelling unit (ADU) is an additional, smaller dwelling unit on a lot with, or in, an existing home. These units are intended to facilitate land efficiency, encourage affordable housing options, and provide a range of choices of housing types in the city’s residential districts. The ADU is intended to be subordinate in size, location and function to the primary residential unit. An ADU is commonly referred to as a  ‘mother-in-law’ apartment or ‘granny flat.’

Types of ADUs

Where is an ADU allowed?

An ADU can be located on residentially opens in a new windowzonedopens PDF file property that has an existing single-family residence.

How is a Guest House Different?

Per the Poulsbo Municipal Code (PMC), a Guest House is a detached accessory building designed, constructed and used for the purpose of providing temporary living accommodations for guests, or for members of the same household as that occupying the main structure, and containing no kitchen or kitchen facilities.  One guest house may be permitted on a residential zoned lot, limited to 800 square feet in size and 25 feet in height.

Benefits of an ADU
  • Can provide a source of income for homeowners;
  • Allows homeowners the flexibility to create a home to share with family members and others;
  • Offers an opportunity for multi-generational living, allowing seniors to age in place as they require more care;
  • May provide affordable and additional housing opportunities within existing neighborhoods; and
  • A cost-effective way to provide additional housing, by potentially eliminating the cost of purchasing land, installing or building major new infrastructure, or creating new structured parking.

Current Code Allowances

Per opens in a new windowPMC 18.70.070 A

  • Number: One ADU is permitted per parcel and as subordinate to an existing single-family detached dwelling
  • Size: No more than 800 square feet of heated living area; provided, if the accessory unit is completely located on a ground floor or basement, the review authority may allow increased size in order to efficiently use all floor area.
  • Height: A detached ADU shall be limited to 25 feet in height.
  • Owner-Occupied: The owner must occupy either the primary residence or the ADU.
  • Parking: One (additional) off-street parking space provided for the ADU.
  • Design: Detached ADU shall be consistent in design and appearance with the primary structure.
  • Entrance: The ADU entrance shall be subordinate to the primary structure’s entrance, and oriented away from the view of the street or designed to appear as a secondary entrance to the primary unit
  • Occupants: The total number of occupants in both the primary residence and the ADU combined may not exceed the maximum number established by the opens in a new windowdefinition of “household.”
  • Setbacks/Lot Coverage: The ADU shall meet all opens in a new windowzoning requirements, including lot coverage and setbacks.
  • Short Term Rental: May not be used as a short-term rental and must be rented for a minimum of ninety days or more (note: the City of Poulsbo does not regulate short term rentals).
  • Mobile Homes/RVs: Mobile homes, manufactured homes, or recreational vehicles shall not be considered an ADU.

Permitting Process