A: Pole barns (post-built structures) look simple at a glance. However, in terms of structural design for wind, snow and seismic forces, they are much more complex than a conventionally build structure such as a stick-built home.
In addition, the prescriptive codes (Residential) tell how to frame conventional structures.
Structures other than prescriptive are required to be designed per the Oregon Structural Specialty Code. The design, which is required to be done by an Oregon Licensed Engineer or Architect, is done on a case-specific basis for the loads and parameters of the structure.
There are certain conditions where these structure are exempt from building permits. "Agricultural Building" and "Equine Facility" are defined in Appendix C of the Oregon Structural Specialty Code and can be viewed online at http://www2.iccsafe.org/states/oregon/
Even if the structures meet the definition to allow the exemption for building permits, a development permit is required by the Planning Department and DEQ needs to approve the location in regards to the septic system.
The procedure for an exemption from building permits is to fill out an affidavit at the Building Department stating that the intended use of the structure complies with the criteria as defined by Appendix C. If exempt, plan check/building permits/inspections are not required.
A: See "Design Criteria" located under "Documents and Forms".