I was going to ask what SWP meant; they're usually called Wood Structural Panels.

I agree with all of the above statements but would add that the edges of OSB swell when wet and do not shrink back as well as the edges of plywood do so OSB must be stored and handled with greater care. If that is considered less "durable" then OSB is less durable than plywood but it matters little if handled and installed properly.

I specify 3/4" OSB for roof sheathing for the better nail withdrawal rating but 5/8" is far better than 1/2 in that regard. When OSB is used for sub flooring it should be treated for resistance to water (eg AdvanTech, etc.)

Structural 3/8" ply panels can be designed and nail for wall shear panels.

What about for walls? Is 1/2" thick enough?

Nail withdrawal for walls is not as critical as for roofs so 1/2" is fine. Lateral force resistance is dependent on the nailing schedule.

Absolutely cpartist.

Thanks JDS and millworkman.

Isn't it funny that anytime I read something on here about building, I have to go and check my plans and specs to see how they're planning on doing it. (And I'm guessing I'm not the only one.)

Thanks everyone for taking the time to reply.

I will point out an argument that I've been making for years, which is that in general, I really hate the 'osb vs. plywood' question. There are some extremely well engineered OSB panels that stand up very well to the elements, and some cheap, low-ply plywood I wouldn't put on a dog house. And the opposite is true, also. Without specifying the product, I'd hesitate to say one is better (or worse), than the other.

Great points from everyone. Another is that plywood and certain brands of OSB accept tape without the added PIA and expense of added primer for adhesion.

Thirty years ago, a building partner of mine fell right through OSB roof sheathing and landed in the basement. Survived in one piece, he's been skeptical about its wonderfulness ever since. I've only used it for wall sheathing behind brick.