gypsum shear walls

huangyhg

gypsum shear walls
re: ibc 2306.4.5  i know i've used this table in the past, and i thought that the table represented gypsum used on only one side of wall.  therefore sheathing both sides allows me to double the values.  but, i'm not reading this anywhere.  
also, there does not seem to be any reduction factors for gypsum as there is for structural wood sheathing.  
please advise ...   thank you ...
i don't actually see where it says you can double the shear values for wood walls either, yet we do it on a regular basis.
i think there is no specific gravity reduction on gwb walls because the gypsum is going to fail long before the wood does, and the reduction is based on stud species.  i would take the table at face value.
just a thought....
ibc 2305.3.8 summing shear capacities
"the shear values for materials of the same thickness applied to both faces of the same wall are cumulative"
the problem with using gwb on both sides of the wall to  resist lateral loads, is the fact use of sound channels.
unless the gwb is applied directly to the wall studs it is not effective in resisting shear.