Do your on test. Put a screw into 5/8 plywood and then do the same in OSB. I grant you I can pull the screw straight out of the OSB with little effort.
Are we comparing apples to apples here with 5/8s plywood and 19/32's OSB? Or are you comparing the 5/8 plywood to 7.16's OSB?
Are you using the same type and length of screws in your test?
I find it just about impossible to believe that you can pull a screw out of OSB with little effort. Heck, it takes effort to do this with a nail. Pulling screws out of OSB with my pry bar destroys the OSB when coming out. Usually when I pull screws out of 7/16 OSB, the head either breaks off or the wood around the screw comes out and creates a volcano looking area where it came out.
I've never tried this with 5/8 plywood, nor have I tried it with 19/32 OSB. While I'll give you that it will be harder to get that same screw out of plywood that is thicker then OSB, I'll also give you that if we were to measure the amount of force needed to pull a screw out of both types of wood with the same thickness, the plywood would be more. How much more is where it gets interesting and where I doubt the difference is significant.
Lots of times, people will overbuild for a variety of reasons. Usually it's a good intention, but in the end, they have just wasted money without any measurable improvement. It's real easy to spend allot of money to build a house, but it's more challenging to build just as strong a house with less money or alternative materials.
Eddie
