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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 zoned 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 PMC 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
  • Setbacks/Lot Coverage: The ADU shall meet all zoning 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: Recreational vehicles shall not be considered an ADU.

Permitting Process

  • Type I: ADU is internal to the primary residence (e.g., basement), and no increase in square footage of the residence. No public notice is required.
  • Type II/ACUP: New internal and/or attached ADU in which an increase in square footage of the residence is proposed. Public notice is required.
  • Type II/ACUP:New detached ADU (including detached accessory structure or garage), or conversion of an existing detached structure or detached garage, an ACUP/Type II permit is required. Review time is variable but cannot exceed 120 days.
  • Fees: See Fee Schedule for current land use permit fees.
  • Building Permit: After obtaining the land use permit, the owner is required to apply for a building permit.