Building Official Determination 26-01: Seismic Standard Alternate

Information

Option to use structural requirements for existing buildings when a seismic upgrade is required.

Building Official Determinations (BODs) provide answers about the application of building codes and outline optional alternatives.

Portland City Code Section 24.85.040, Table 24.85-A, OSSC Table 1604.5

PCC Title 24.85 requires structural improvements to existing buildings when more than 1/3^rd of the floor area of the building changes to a higher relative hazard classification. The structural improvements must meet either ASCE 41-BPOE (Basic Performance Objective for Existing Buildings) or ASCE 41-BPON (Basic Performance Objective Equivalent to New Building Standards) based on the final occupancy classification of area changed.

QUESTION: Are there allowances for a building to conform to ASCE 41-BPOE instead of ASCE 41-BPON when the occupancy classification(s) of the area changed are in Relative Hazard Category 5 or 6 as outlined in PCC Table 24.53-A?

RESPONSE: Yes. Where both of the following conditions are met, seismic improvements required under Title 24.85 may be designed to the ASCE 41-BPOE standard.

The proposed change of occupancy/use does not result in the building being assigned a higher Risk Category in OSSC Table 1604.5.
The building is a single story above grade plane.

Structures using this BOD may also use the options in BOD 25-02 Seismic Benchmarking.

HISTORY: Implemented May 4, 2026.

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