• 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 2014 Oregon Structural Specialty Code (OSSC), which is based upon the 2012 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 2010 edition of Minimum Design Loads for Buildings and Other Structures (ASCE 7-10) or in accordance with the alternate method contained in the OSSC (if applicable). The design wind speeds 3-second gust for the City of Portland are:

    Risk Category Vult (mph)
    I 115
    II 120
    III, IV 130

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


    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 ORSC (Oregon Residential Specialty 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.

    Miscellaneous Structures

    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. Please visit the BDS Signs webpage for more information on the Sign permitting process.

    Floating Structures Floating Structures are governed by the City of Portland Title 28.