Plywood loads per APA vs NDS

[struct_eeyore]

Hi all,

I've run into a discrepancy between tabulated plywood loads given in APA(IBC) and NDS. For example - I'm looking at sheathing grade panels, 7/16" with 24" centers on supports (no edge supports). NDS gives me 135psf nominal/1.6 = 84.something... looking in the IBC (APA span loads) gives 50 psf (so I'm taking (50/1.25)*1.6 = 64... is this discrepancy solely due to deflection limits in APA (granted, one table is specifically for wind and the other for gravity). Any and all comments appreciated. Thanks.

 

[dianium500]

I have always used APA for plywood design and NDS for dimensional lumber only. APA is the expert when it comes to plywood in my opinion. They also set all the span ratings that the manufacturers use to stamp the plywood. Also, have you looked at the APA published materials themselves and not just the IBC? They have several values; some due to bending, some due to deflection limitations...etc. They are your best source in my opinion.