Lightweight steel framing system

[ick2]

I will use lightweight joist construction for a residencial project. Since my joists are 12" o.c. I am using a form deck UFS 9/16" thick and 2 1/2" slab. This gives a capacity of 480psf for a single span. However i have seen residential construction where for the same application people are using 1 1/2" deck plus 4" slab. Is there a reason for this?

 

[whyun]

Fire rating?

 

[Lutfi]

Other reasons could be that the supports are spaced farther apart (more than 12 inches on center). Another possiblity, is the required floor loading is higher.

 

[boo1]

sound?

 

[emceditor]

Floor vibrations are quite a bit less with the higher mass 4" slab thickness.

 

[ick2]

thanks all for your replies