Building Code Guides (BCGs) and Building Official Determinations (BODs) provide answers about the application of building codes and outline optional alternates. BODs are typically smaller in scope and address simpler questions. Code Guides provide a comprehensive alternative to a complicated set of code requirements.
BOD 96-02: Assembly in Pre-1979 Group B Occupancies
QUESTION: Prior to 1979 the Building Code classified small assembly occupancies (with occupant loads less than 100) as Group B - Division 2 occupancies. The 1979 Code changed that threshold to less than 50 occupants, thereby classifying those between 50 and 100 occupancies as Group A - Division 3. Occupancies with less than 50 occupants were still classified as Group B - Division 2 occupancies. In 1996, Group B - Division 2 occupancies were revised again to be simply Group B occupancies. The Oregon Structural Specialty Code (OSSC) now states that a building or tenant space used for assembly purposes by less than 50 persons shall be classified as a B occupancy.
- Pre-1979: Assembly occupant load < 100 = Group B - Div 2
- 1979-1996:
- Assembly occupant load < 50 = Group B - Div 2
- Assembly occupant load 50 < 100 = Group A - Div 3
- 1996 to present:
- Assembly occupant load < 50 = Group B
- Assembly occupant load 50 or greater = Group A (A-2 for drinking and dining establishments, A-3 for worship, recreation or amusement)
How are existing assembly occupancies with an occupant load between 50 and 100 regulated? When is a change of occupancy required?
RESPONSE: This BOD applies to Group B assembly occupancies with an occupant load between 50 and 100 that existed on or before July 1, 1979. Such pre-existing status must be clearly documented by existing permit records.
Maintenance
Existing Group B assembly occupancies with an occupant load between 50 and 100 may remain classified as Group B occupancies and be maintained including normal repair work, without requiring a change of occupancy. Group B exit hardware will be allowed in these instances.
Alteration and Additions
Existing Group B assembly occupancies with an occupant load between 50 and 100 may be altered or added to, without requiring a full change of occupancy provided:
- The exit hardware, signs and lighting are brought into compliance with Group A, Division 2 requirements;
- The alteration or addition does not increase the occupant load of the occupancy to more than 100 persons including staff and customers;
- Any change or expansion of the floor construction is designed to carry the required design loads prescribed in Chapter 16;
- Altered elements shall comply with accessibility requirements of Chapter 34 of the OSSC; and
- Permit applications for such occupancies shall include the designation of Group B occupancy and shall include a seating layout noting the number of occupants and designated exits. A note is to be included in the City permit tracking system which states this occupancy is classified as a Group B based on the occupancy being established prior to July 1, 1979.
Changes of Occupancy
A full change of occupancy will be required to expand any existing Group B assembly occupancy to accommodate more than 100 occupants, including staff and customers.
Where a tenant space is currently classified as a Group B but is not currently used as a dining or drinking establishment, a full change of occupancy will be required to establish any dining and drinking establishment with an occupant load of 50 or more.
Conference rooms, employee lunch rooms or other similar rooms or areas used for assembly type purposes that are accessory to another occupancy may be considered part of that occupancy as specified in the OSSC.
HISTORY: Code Guide IBC/3/#2 replaces Code Guide UBC/6/#1 which replaced Policy & Procedure # D-48. Updates August 22, 2007, July 14, 2006, March 1, 1999, July 1, 1996, and July 24, 2024.
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