Appeal 31722

2019 OSSC §507.4.1

Per OSSC §507.4.1, Group A-2 occupancies of other than Type V construction shall be permitted within mixed use occupancy buildings of unlimited area complying with Section 507.4, provided all of the following:

1. Such Group A-2 occupancies are separated from other occupancies per Section 508.4.4 with no reduction for automatic sprinkler system;
2. Each area used for such occupancies shall not exceed the maximum allowable area permitted per Section 503.1;
3. Exit doors discharge from such occupancies directly to the exterior of the building.

This request is to provide A-2 occupancy within an existing unlimited area building of Type V B construction with the addition of a 2-hour rated fire barrier separating the Group A-2 occupancy from the remainder of the unlimited area building.

The Cali-Saigon Mall was constructed in 1967 as a single-story retail store. The area of the shopping center is 93,684 square feet and it currently supports Group B, M, and S-1 occupancies with a supermarket and a variety of retail stores. The permitted construction is Type V B following the provisions for unlimited area mixed occupancy buildings.

The proposed renovation of 12,682 square feet at the southwest corner for a Group A-2 restaurant meets all the requirements for a Level 2 alteration, except A-2 occupancy is not allowed in an unlimited area Type V building per 507.4.1. The proposed design will be for the A-2 occupancy restaurant to be separated from the other occupancies with a 2-hour rated fire barrier per OSSC 707.3.10. The A-2 occupancy will have two exits directly to the exterior with no mall occupants required to exit through the A-2 occupancy.

RECONSIDERATION TEXT:

Smoke detectors will be added in the restaurant seating area and connected to the fire alarm system.

The rated wall goes up to the rated roof sheathing with a flexible wall head connection (see detail 5, sheet A7.10).

The current structure classifies as a fully sprinklered Type V-B construction type with mixed occupancies. The building is of tilt-up concrete panels with unprotected steel columns imbedded in the panels. The roof construction is wood joists on glu-lam beams 14 feet above the floor.

Per 2019 OSSC, Type V-B construction refers to building’s where the construction permits use of wood or other approved combustible materials for structural elements. Per OSSC §507.4.1, within mixed occupancy buildings of unlimited area, Group A-1 and A-2 occupancies of other than Type V construction shall be permitted.

The intent of OSSC §507.4.1 preventing A-1 and A-2 occupancies from being in unlimited area mixed occupancy Type V buildings is due to the high occupant load that is unfamiliar with the space. The potentially large number of occupants would take additional time to egress from the middle of an unlimited area building. Type V construction has the potential for quick fire spread with this high occupant load.

The intent of this appeal is to locate the A-2 space at the corner of the building, with direct egress to the exterior on two sides, and to separate the space as a fire area from the rest of the building. The change in occupancy classification of the corner space from an M occupancy to an A-2 occupancy will exceed the requirements of §508.4 for 1-hour separation. Fire barriers, used for separating the occupancies, play a crucial role in ensuring building safety by preventing the spread of fire and smoke. They are an essential component of passive fire protection systems and are designed to compartmentalize a building, limiting the spread of fire from one area to another.

By separating assembly occupants and egress paths from the rest of the retail building, any fire/smoke event in either area will trigger the building fire alarm and occupants will have additional time to egress. The occupants of the assembly space will have direct access to two exits directly to the exterior, ensuring quick egress times, even though being unfamiliar with the space.

To facilitate the change of occupancy to A-2, the proposed design aims to provide extra protection to the fire barriers separating the A-2 from the B, M and S-1 occupancies, which would help increase the overall structural stability more than that defined by the OSSC. The current design follows the requirements of §507.4.1 where:
• The A-2 occupancy is separated from the other occupancies as a separate fire area;
• The area used for the A-2 occupancy does not exceed the allowable area permitted in §503.1; and
• The exit doors discharge directly to the exterior of the building.

For separated occupancies per §707.3.9 and §508.4, the required rating for separation of A-2 occupancy from Groups B, M and S-1 is 1 hour. The project intends to increase this rating by creating a 2-hour rated fire barrier per Table 707.3.10. The fire rating determines the duration for which the barrier can resist the spread of fire and maintain its integrity. Refer to the attached detail showing the wall assembly construction.

Additional protection is also provided by non-combustible exterior wall construction, and the building has at least 60' of frontage with parking on three sides and at least 30' on the west side including public right-of-way.

By effectively separating the occupancies with higher fire resistance utilizing a 2-hour rated fire barrier, the proposed design provides greater protection for the assembly and mall occupants. Hence, we request you to grant this appeal.

RECONSIDERATION TEXT:

The addition of smoke detectors in the restaurant seating area connected to the fire alarm system provides early detection and early initiation of egress in the case of a smoke event.

The 2-hour fire rated fire barrier offers a means to offset the impact on life safety as acknowledged by the City of Portland Plan Reviewer. The 2-hour rating is provided in excess of the 1-hour occupancy separation requirement. The fire barrier creates separate fire areas and provides additional protection for occupants of the mall.