Standard Seismic Applications Guide - IBC Category D, E, F
Standard IBC
Category C		 Standard IBC
Category D,E,F		 Alternate IBC
Category C		 Alternate IBC
Category D,E,F
The following are all the IBC Category D,E,F2 Code Requirements for lay-in acoustical panels and direct-hung acoustical tiles. Rollover items in the list to view and download additional diagramatic drawings.

Basic Connections, Perimeter, and Lateral Splay Bracing

Requirements
Minimum intersection strength limits @ MT / CT 180 lbs
Vertical hanger wire 12-gauge @ 4' o.c. Required
Connection device from vertical wire to the structure above must sustain min 100 lbs Required
Main tee classifications Heavy-duty
1 in 6 max plumb of vertical hanger wires Required
Perimeter vertical hanger wires not more than 8" from wall Required
Grid end/wall clearance Min 3/4"
Perimeter closure (molding) width Min 2 "
Grid connection to perimeter attached on two adjacent walls Required
Perimeter tee ends tied together Required
Horizontal restraint (splay wires or rigid bracing) within 2" of intersection and splayed 90° apart at 45° angles Required
Compression posts (struts) 12' o.c. in both directions, starting 6' from walls Required
Splay bracing connection strength 200 lbs or the design load, whichever is greater Required
Partition attachment Bracing independent of ceiling splay bracing
Seismic separation joint4 Required for areas > 2,500 sq. ft. (or full height partition)
Rigid bracing for ceiling plane elevation changes Required

Light Fixture Attachment

Requirements
Light fixture (all types) mechanically attached to grid NEC 410-16 (two per fixture unless independently supported) Required
Surface-mounted fixtures attached to grid Not required
Pendant-hung fixtures directly supported from structure with 9-gauge wire (or approved alternative) Required
Rigid lay-in or can light fixtures
< 10 lbs – one wire to structure (may be slack) Required
10 to 56 lbs – two wires from housing to structure (may be slack) Required
> 56 lbs – supported directly to structure by approved Required

Service Applications

Requirements
Air terminals
< 20 lbs – positively attached to grid Required
20 to 56 lbs – positively attached to grid and two wires to structure (may be slack) Required
> 56 lbs – directly supported to structure Required
Sprinkler heads and other penetration clearance Min 2" dia. opening or a swing joint
Cable trays and electrical conduit independently supported and braced Required

Notes

1. Refers to CISCA installation recommendations for zones 3-4 via ASCE 7-02.

2. The above information is correct to the best of our knowledge at the date of issuance. Because codes continue to evolve, check with a local official prior to designing and installing a ceiling system. This is only intended as a quick reference. A thorough understanding of IBC 2003 and UBC 25-2 is necessary when designing and installing ceiling suspension systems.

3. Required for ceilings larger than 1,000 square feet.

4. Where substantiating design calculations are not provided.