This seismic design diagram outlines the framing and bracing requirements for suspended acoustical ceilings. The layout indicates heavy-duty main runners set at four feet on center maximum with acoustical panels and twelve-gauge support wires placed eight inches maximum from walls and four feet on center each way. Lateral bracing and seismic struts are required for fixed-end walls with specific spacing limits, including twelve feet maximum between lateral bracing and six feet maximum from walls. Adjacent free-end walls utilize loose seismic perimeter clips, while fixed walls require tightened seismic clips and tee interlocking connections when cross runners exceed twelve inches from the wall. Rooms under one thousand square feet are exempt from lateral bracing, whereas rooms exceeding twenty-five hundred square feet require a seismic separation joint.
FREE END FREE END FIXED END FIXED END MR INDICATES 12 GAUGE SUPPORT WIRES, PLACE 8" MAX FROM THE WALLS AND 4'-0" O.C. MAX EACH WAY IF CROSS RUNNER IS GREATER THAN 12" FROM WALL, PROVIDE TEE INTERLOCKING CONNECTION FOR THE TWO ADJACENT FREE END WALLS PROVIDE LOOSE SEISMIC PERIMETER CLIPS HEAVY DUTY MAIN RUNNER SET AT 4'-0" O.C. MAX TYP AND 2'-0" O.C. AT 2 X 6 AND LARGER ACOUSTICAL PANELS CROSS RUNNER INDICATES LATERAL BRACING DETAIL WITH SEISMIC STRUT FOR THE TWO ADJACENT FIXED WALLS PROVIDE TIGHTENED SEISMIC PERIMETER CLIPS MR MR F R O M W A L L 4 ' M A X L A T E R A L B R A C I N G 8 ' M A X B E T W E E N MR 8 " M A X 8 " M A X F R O M W A L L 6 ' M A X A L O N G M A I N R U N N E R S 1 2 ' M A X B E T W E E N L A T E R A L B R A C I N G 8 " M A X 8 " M A X SEE SEISMIC STRUT DETAIL D1/ A592 SEE SEISMIC EDGE DETAIL B1/ A592 ROOMS WITH A CEILING AREA OF LESS THAN 1000 SQUARE FEET DO NOT REQUIRE LATERAL BRACING OR SEISMIC STRUTS. ROOMS OVER 2500 SQUARE FEET REQUIRE A SEISMIC SEPARATION JOINT. SEE SEISMIC EDGE DETAIL B1/ A592
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