• Structural Design Requirements

    The following items address frequently asked questions concerning structural design requirements within the jurisdiction of the City of Portland.


    General Design Requirements
    The following requirements are applicable to both commercial and residential projects located within the jurisdiction of the City of Portland.


    Commercial Permits

    The current state building code governing commercial and engineered residential construction is the 2010 Oregon Structural Specialty Code (OSSC), which is based upon the 2009 International Building Code (IBC) as amended by the State of Oregon.

    Wind: Design wind pressures are to be determined using the 3-second gust wind speed and the procedures of the 2005 edition of Minimum Design Loads for Buildings and Other Structures (ASCE 7-05) or in accordance with the alternate method contained in the OSSC (if applicable). The design wind speeds for the City of Portland is 95 MPH (3-second gust).

     

    Wind exposure category is site dependent and must be determined by the Engineer of Record based upon site conditions.

     

    Seismic:

    Five Stories of Wood-framed Residential Construction over a Concrete Podium:
    See Frequently Asked Questions on this topic.


    Residential Permits

    The structural requirements for residential projects may be either prescriptive or engineered.  In prescriptive design, the Code defines a conservative method of construction to resist vertical and lateral loads.  In engineered design, an engineer licensed in the State of Oregon prepares engineering calculations and drawings that demonstrate how the structure resists vertical and lateral loads.

     

    View the current State Building Codes and Rules. Refer to Commercial Permits, above, for information regarding engineered residential design.

     

    The following are design values may be used for prescriptive residential design:

    Wind: Applicable design wind pressure is 18 psf.
    Seismic: Applicable Seismic Design Category is D1.

    Transmission and Cell Towers
    Design loads shall be determined per Structural Standards for Steel Antennae Towers and Antennae Supporting Structures (TIA/EIA-222 F-96).  The structural design must account for atmospheric ice loads and increased wind load on ice covered sections

     

    Signs and Fabric Covered Awnings
    Signs and fabric covered awnings are governed by City of Portland Title 32.

    Signs: Structural design per Title 32.42.010.
    Fabric Covered Awnings: Structural design per Title 32.52.010.

    Floating Structures

    Floating Structures are governed by the City of Portland Title 28