I think the datasheet <http://www.nwcb.org/images/resource_files/401%20Suspension%20Systems%20 for%20Acoustical%20Lay-in%20Ceilings(2009).pdf> posted on the Northeast Wall & Ceiling Bureau's Website is confusing people.
The ONLY time that over sized rings or flexible connections are NOT required on an ASCE7 D, E, & F ceiling system, is when RIGID braces are used on the ceiling system (not wires). This is not a common practice. If you see splay wires running at a 45 degree angle (and not rigid braces, like the figure 6b and figure 2 on the data sheet) then this system does not qualify for the exemption; and the over sized ring/flexible drop/swing joint IS required. Also, ceilings that incorporate lateral bracing are NOT exempt (see splay wires in figure 2 on data sheet), unless rigid braces are utilized in lieu of splay wires to limit lateral deflection. The following is an excerpt ASCE 7-05: "ASCE 7-05 13.5.6.2.2: C. For ceiling areas exceeding 1,000ft2, horizontal restraint of the ceiling to the structural system shall be provided. The tributary areas of the horizontal restraints shall be approximately equal. EXCEPTION: Rigid braces are permitted to be used instead of splay wires. Braces and attachments to the structural system above shall be adequate to limit relative lateral at a point of attachment of ceiling grid to less than .25 in for the loads prescribed in 13.3.1. E. Except where rigid braces are used to limit lateral deflections, sprinkler heads and other penetrations shall have a 2inch oversize ring to allow for free movement of at least 1" in all directions. Alternatively, a swing joint that can accommodate 1inch of ceiling movement in all horizontal directions is permitted to be provided at the top of the sprinkler head extension. " Incidentally, flexible sprinkler drops do qualify as an alternative to the swing joint above because they allow 1 inch of lateral movement. FlexHead is the only flexible connection to undergo full scale seismic testing and become seismically qualified to ICC AC156. If anyone is interested in seeing the full scale seismic testing report or a video clip of the testing, please contact me offline. Norm MacDonald FLEXHEAD Industries, Inc.. 56 Lowland Street Hollsiton, MA 01746 (508) 893-9596 TEL (508) 893-6020 FAX [email protected] <mailto:[email protected]> EMAIL www.flexhead.com <http://www.flexhead.com> WEBSITE _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
