Building Code Guides (BCGs) and Building Official Determinations (BODs) provide answers about the application of building codes and outline optional alternates. BODs are typically smaller in scope and address simpler questions. Code Guides provide a comprehensive alternative to a complicated set of code requirements.
BOD 21-05: Habitable vs. Non-habitable Accessory Structures
QUESTION: When is a heated detached accessory building considered a “non-habitable” structure and, therefore, exempt from permits under Section R105.2(1)?
RESPONSE: The Oregon Residential Specialty Code (ORSC) does not require a building permit for non-habitable detached one-story accessory structures with a building area 200 square feet or less. State of Oregon Statewide Code Interpretation 03-01 clarifies that the structure can be heated and still be considered "non-habitable" as long as it does not have a living room, dining room, kitchen, bedroom, or any combination of these types of rooms.
Since "living room" can apply to a variety of uses, the City of Portland will allow a heated accessory structure that meets the size and height limitations of R105.2(1) to be exempt from a structural building permit if it meets all the following conditions:
- The structure does not contain a kitchen.
- The structure will not be used for overnight sleeping.
- The structure will not be used for a business, including licensed child care and home-based businesses operating under a Home Occupation Permit.
Where the accessory structure includes a covered porch, the floor area will be measured to the edge of the dripline of the porch cover.
Note: Although a structural building permit is not required, the work must still be constructed to the provisions of the building code. The exemption from a structural permit does not negate required trade permits when applicable such as electrical, mechanical, and plumbing. The accessory structure may require a zoning permit. Zoning requirements for floor area and building coverage limitations on the lot apply. Please check your zoning allowances by calling the Zoning Information Line at 503-823-7300 or scheduling a 15-Minute Question Appointment.
HISTORY: Implemented December 5, 2019. Revised May 17, 2021 and March 8, 2024.
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