Building Code Guide 19-11: Townhouses

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.

BCG 19-11: Townhouses 

QUESTION: The Oregon Residential Specialty Code (ORSC) defines a townhouse as: 

"A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides." 

Does the City of Portland allow any deviations from this definition?

RESPONSE: Each townhouse is limited to a single-family dwelling unit separated from the adjacent dwelling unit by a fire-resistance-rated wall assembly extending from the foundation to the roof. The City of Portland has determined that the following alternative design options are allowed.

1. New definition for the purpose of this code guide. 

   TOWNHOUSE STRUCTURE: A group of attached townhouses

2. Two attached units: The City of Portland allows a townhouse structure to be constructed as a group of two attached townhouses in which each unit extends from foundation to roof instead of a minimum of three townhouses.
3. Townhouse with ADU: One or more townhouses in a townhouse structure may be constructed as an attached two-family dwelling where all of the following conditions are met:
   1. One of the two dwelling units within the townhouse shall conform to the City of Portland’s requirements for Accessory Dwelling Units (ADUs), including all requirements in the ADU Building Code Guide; and
   2. Each two-family dwelling within the townhouse structure shall meet the definition of Attached House in Portland City Code Title 33, Planning & Zoning, including that it is located on its own lot. For purposes of Title 33, each attached two-family dwelling shall be considered an Attached House with an ADU; and
   3. NFPA 13-D fire sprinklers shall be installed throughout the townhouse; and
   4. The fire rating and/or fire rating continuity reductions in Section R302.2 shall not be permitted; and
   5. When a townhouse is constructed as a two-family dwelling unit, only the primary dwelling unit must have access to a yard or public way on not less than two sides. At least one full side of the ADU shall have access to a yard or public way; and
   6. Common spaces serving only the ADU and primary dwelling unit are permitted when the common space is fully contained between the 2-hour fire-resistance-rated townhouse separation walls. The common spaces must be separated from the primary unit and ADU as outlined in the ADU Code Guide.
   7. When a townhouse with an ADU is built as a four-story structure using the Four-Story Code Guide, the following conditions must be met in addition to the requirements in the code guide:
      1. NFPA 13-R fire sprinklers shall be installed throughout the townhouse under a permit through the Fire Marshall’s Office.
      2. Any dwelling unit that has enclosed usable space on more than three levels shall be provided two means of egress, each with an egress door to the exterior on a different level.  This means each egress door must be located at grade or provided access to grade by a code compliant ramp or stairway.
4. Common Space: Mixed occupancies are not permitted in townhouse structures. However, one common storage space, such as a trash room or bike parking, serving the occupants of the townhouse structure is permitted when all of the following conditions are met:
   1. The area of the common space shall be no larger than 150 square feet; 
   2. The common space shall be separated from the other areas of the townhouse structure with 2-hour fire-resistance rated horizontal and vertical assemblies. The supporting construction for these horizontal and vertical assemblies shall also be 2-hour fire-resistance rated; and
   3. The common space shall be protected with NFPA 13-D sprinklers.
5. Means of egress to public way: Required egress doors and emergency escape and rescue openings (ERROs) shall open directly into a public way or to a yard or court that opens to a public way. Where an egress door or ERRO does not open to a yard that fronts onto the public way, the site plan must show a 36-inch wide path identified "36-inch wide path to remain unobstructed." The City of Portland will allow fences to cross the path as long as there are gates unlocked in the direction of egress for occupants to maintain access to the public way.  

Alternative proposals not meeting the requirements of this code guide, with the exception of C.2, will be considered on a case-by-case basis through the building code administrative appeals process.

HISTORY: Implemented September 16, 2019. Revised April 15, 2024.

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