Originally Posted by Jim Bennett
OSB is just structurally just as strong, or stronger than plywood can be, and is no more flammable. Lots of these old myths still abound. Plywood is much better for putting a finish product on though.
Agreed, that OSB is structurally an excellent choice. However, plywood, having discrete veneer layers, has more initial resistance to degradation by water. OSB soaks it up and swells quite nicely.
I did mention the OSB on the walls, as it is not as an effective membrane for fire-protection as gypsum board. Gypsum is a hydrated calcium salt that aids in fire attenuation when heated, thus driving off the water.
I am aware of a somewhat contradictory test by Warnock Hersey that was commissioned by the OSB industry. So, the beat goes on!
But, fire sprinklers are very, very effective. We like them; they save lives and property.