Code Official's Role
The building code presents minimum design/performance requirements and in some instances prescriptive guidance. The code also sets forth limitations and conditions of use. It is important to know that while the building code establishes the requirements, the code official has the power to enforce its provisions. The code official also has the latitude to allow materials and methods of construction that are not addressed in the code. A code official can perform their own analysis of evidence presented or can rely on independent, qualified sources such as ICC-ES to do the analysis and provide their findings.
Seismic Codes and Requirements Resources:
FEMA and IBC
Federal Emergency Management Agency (FEMA)
Seismic performance during large California earthquakes prompted the Federal Emergency Management Agency (FEMA) to address suspended ceiling performance during a seismic event. Research and tests demonstrated that industry seismic standards (UBC Standard 25-2) were not adequate. To support individual panels around the perimeter, FEMA determined that the key to good seismic performance is a wider wall molding on all sides. This led to the International Building Code requirement for 2" wall molding on all sides.
Source: FEMA 302 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures
Adoption of the International Building Code (IBC)
Currently all 50 states as well as Washington, D.C. and the Virgin Islands use the International Building Code.
Seismic Design Categories
The seismic design category must be specified by a professional engineer or registered architect on the project drawings per ASCE 7. The project requirements which include the seismic design category can be found in Section 1 of the specification and on the first page of the structural drawings.
International Building Code (IBC) allows two paths to determine Seismic Design Category – IBC Section 1613 or ASCE 7 Section 11.6. The IBC states that a Seismic Design Category must be established for each construction project based on:
- Anticipated ground motion
- Soil type in a specified geographic area
- Occupancy category
These factors are used to evaluate and establish a Seismic Design Category of A, B, C, D, E, or F. The installation of ceilings can be divided into three tiers of increasing requirements:
- Categories A & B are installed to meet requirements established in ASTM C636
- Category C projects must meet those plus additional provisions listed in ASTM E580
- Categories D, E & F must follow ASTM C636 and ASTM E580
NOTE: Seismic categories are determined for the entire building. This is why the Seismic Design Category information is on the structural drawings.
