Multi-Family Floor/Ceiling Assemblies
2003 IBC Section 1207 requires a minimum STC=50, and a minimum IIC=50, at floor/ceiling assemblies separating dwelling units. In the past most floor/ceiling assemblies using wood I-joists required one layer of 5/8" type 'x' gyp brd attached to rc channels attached to the wood I-joist, mainly to achieve a one-hour rating as I understand it. In researching many different wood I-joist manufacturer's testing reports, I can only find one similar to this. It is TJI's ICC ES PFC-4354, Assembly B. However is shows under its Assembly B on page 21 of this report that two layers of 5/8" type 'x' gyp brd are required over rc channel to achieve a minimum IIC=50.
Anyone out there know of a valid report with one layer of 5/8" type 'x' gyp brd attached to rc channel attached to wood I-joists that meets the 2003 IBC 1207 requirements?
posted by el yunque at 3:52 PM
5 Comments:
To achieve a minimum IIC=50 on floor systems normally you will have to carpet the floor areas to get a 50 rating. The tile or vinyl floor covings will almost be impossible to get the 50 rating without the double layer of 5/8 drywall. I will look into some different systems.
Thanks. Part of my reason for asking about this is that we have required on multi-family projects the two layers of 5/8" type 'x' gyp brd per Assembly B, but have gotten heat from a couple of our clients who claim that they are doing work on other multi-family projects where they are still just putting one layer in over RC channel . . . and why are we wasting their money, etc . . . the usual comments I'm sure you hear many times each day.
We had a meeting on sound transmission on Thursday in Riverton. It was presented by Alcorp. The person who presented was Rodger Maki at 623-551-5123. I missed the first part of the presentation but he showed some floor ceiling assemblies etc that would meet the IIC 50 and he felt like you would really have a difficult time meeting this with a wood floor. It was a good presentation. Roger said he would welcome any call or question regarding sound transmission.
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I was reading your comments about the sound issues, using one layer of wallboard attached to RC-1 on an I-Joist and how to achive a 50IIC/STC. Which is required by IBC code. First of all a 50 IIC and STC can be met with one layer of 5/8" drywall in this assembly, however, the problem is meeting the 1 hour fire rating that will most likley need to be met, as well. I do have the answers on how to achive both the fire and sound requirments needed. If anyone is interested, please call me to discuss how to do this at 602-763-7783.
I will also be in Utah during the month of May 2006, so if there is interest in a presentaion on fire and sound assemblies, contact me and i will put one togther for all that would like to attened.
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