Appeal 26156

City of Portland Title 24.85.040 Change of Occupancy or Use

Multiple occupancy changes to a single building may be made under this section without triggering a seismic upgrade provided the cumulative changes do not result in the addition of more than 149 occupants with respect to the legal building occupancy as of October 1, 2004.

This appeal proposes that this building be permitted to add up to 10 percent more occupants with respect to the legal building occupancy as of October 1, 2004, before the seismic upgrade requirements mandated by section 24.85.040 are applicable.

Pacific Center is an existing high-rise building in Portland, OR that consists of a 16-story office tower over 3 stories of below-grade parking. This is an existing permitted building constructed in 1986. The tower is protected with an automatic fire sprinkler system and a voice annunciated fire alarm system throughout. This appeal proposes that this building be permitted to add up to 10 percent more occupants with respect to the legal building occupancy as of October 1, 2004, before the seismic upgrade requirements mandated by section 24.85.040 are applicable.

There is an ongoing concern expressed by building owners, architects, code experts, and even some city officials about the 149-occupant load trigger as it is currently applied to existing buildings in Portland. This approach is unfairly burdensome on large buildings. The state Building Codes Division (BCD) has approved a state-wide alternate materials method SAM 08-05 which permits occupant load increase to be up to 10% of the building area per footnote b to table 1007.3.

“ b) Where the area of the new occupancy with a higher hazard category is less than or equal to 33 percent of the total building floor area, and the total occupant load for the building is not increased by more than 150 occupants (or 10 percent of the existing occupant load, whichever is greater) the building does not require structural improvement unless required by other provisions of this code. “

We urge you to approve the proposed modifications to occupant load threshold that triggers a seismic upgrade to Pacific Center, based on the state-wide SAM attached.

2019 OSSC – Section 1004 Occupant Load; 1004.5 Areas without fixed seating. City of Portland Title 24.85.040 Change of Occupancy or Use

The number of occupants shall be computed at the rate of one occupant per unit of the area as prescribed in Table 1004.5.

To allow flexible workspaces, conference rooms and breakrooms smaller than 750 sf to use an OLF of 1:150 for purposes of determining seismic retrofit triggers (or 1:100 if load factor is being used for both the 2004 baseline calculation as well as the current calculation.) As stated in the proposed city of Portland Code Guide (attached for reference).

N/A

Per the proposed Code Guide, section E1 and E2 that BDS has distributed for purposes of “How to Calculate Load for Office Spaces”:

“For Occupant Load Calculations for Seismic Retrofit triggers: Similar to the calculation for egress occupant load, BDS will use a gross OLF of 1:150 for the full square footage within the exterior walls of office buildings, exclusive of vent shafts and courts.
However, for purposes of determining the legal building occupancy for seismic retrofit triggers in Portland City Code Title 24 Chapter 24.85, flexible workspaces, conference rooms, and breakrooms larger than 750 sf will be subtracted from the gross square footage and calculated using an OLF of 1:15.

We agree with this proposed guideline. It takes into account that the spaces in question are non-simultaneous when it comes to how they are used in office spaces. With that in mind, using an office/business OLF for spaces of this size to determine seismic retrofit triggers is appropriate.