# California Green Building Code 2010 - Sec. 5.714.7.4.3 - Interior sound transmission



## PaulJi (Jun 1, 2013)

The CGBSC 2010 requires an STC 40 for floor-ceiling assemblies between tenant spaces in a project I'm working on.

The situation is the existing building has only 3/4" T&G subflooring and Open web trusses (TJS's at 24" oc.)..without ceiling or carpet etc.

The City Plan Reviewer asked for a floor-ceiling assembly from a lab test report and would accept an assembly in the Gypsum Association's manual.

My contractor states: "I don’t understand the difference between an assembly that consists of joists with a plywood surface above and ACT below, regardless of whether it occurs at a roof or a floor.  Why would the exact same assembly have a different STC rating?"  in other words what is the difference between an STC rated floor-ceiling assembly and an STC rating of a ATC ceiling that one adds below a structural system with a subfloor.

Obviously the contractor would *rather not provide a floor-ceiling assembly * with carpet/padding/plywood or (lightweight concrete) /RC channels and drywall  *in addition to *an ACT lay-in ceiling which by itself has an STC rating of 40.

Is this an code requirement that one could successfully negotiate with a building official?


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## PaulJi (Jun 1, 2013)

I guess my question is whether the code requirements for an STC rating for a floor-ceiling assembly are radically different from the requirements for an STC rating of a ceiling assembly?

*BTW*  There is no requirement for a fire-resistant rated floor-ceiling assembly in this building.


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## mark handler (Jun 1, 2013)

You can also look at the Catalog of STC and IIC Ratings for Wall and Floor-Ceiling Assemblies, as published by the Office of Noise Control, California Department of Health Services http://www.toolbase.org/PDF/CaseStudies/stc_icc_ratings.pdf

Or contact the truss Manufacurer for some of their tested Assemblies

And no there is not a radical difference between FC Assemblies and RC Assemblies, But there is a difference.


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## RLGA (Jun 1, 2013)

GA-600 also has some floor/ceiling assemblies with STC ratings.  However, all of them have some sort of ceiling membrane (tyipically gypsum board) attached to the underside of the joists.  I seriously doubt you will be able to achieve an STC 40 with only 3/4" T&G subflooring.


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## mark handler (Jun 1, 2013)

RLGA said:
			
		

> I seriously doubt you will be able to achieve an STC 40 with only 3/4" T&G subflooring.


You will *NOT* be able to achieve an STC 40 with only 3/4" T&G subflooring


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## ICE (Jun 1, 2013)

Why am I not surprised to learn that the great state of California has an Office of Noise Control?

I wonder, do we have an Office of Nose Control?


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## mark handler (Jun 1, 2013)

We did, I don't think it exists anymore, but the CBC still refers to the manual I posted


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## pwood (Jun 4, 2013)

ICE said:
			
		

> Why am I not surprised to learn that the great state of California has an Office of Noise Control? I wonder, do we have an Office of Nose Control?


 I heard the DEA took over their responsibilities.


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## mark handler (Jun 4, 2013)

"....DEA..." ?


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