1. While plywood and OSB both off-gas formaldehyde, OSB off-gasses more of the carcinogenic gas. Plywood, OSB, and other engineered wood products that contain glue can be stored outdoors for several weeks before construction so that much of the dangerous gasses are vented safely into the outdoors.
2. OSB weighs more than plywood. One 23/32-inch 4x8-foot plywood piece weighs approximately 67 pounds, while a piece of OSB of the same Plywood constructiondimensions weighs approximately 78 pounds. The increased weight of OSB means that it is harder to install and it will put more stress on the house.
3. Compared to plywood, OSB swells more when it comes into contact with water, especially at panel edges. Swell is generally greater in OSB than in plywood due to the release of compaction stress in OSB created during the pressing of wood chips into panels. Swollen plywood will return to its nominal thickness as the wood dries, while OSB will remain permanently swollen, to some degree. Swelling is a nuisance because it can uplift whatever materials lie above, such as tile or carpet.
4. Plywood floors are stiffer than OSB floors by a factor of approximately 10%. As a result, OSB floors are more likely to:
squeak due to floor movement;
cause hard floor surfaces to crack (such as tile); and
result in soft, spongy floors.
5. Nails and screws are more likely to remain in place more firmly in plywood than in OSB.
6. OSB retains water longer than plywood does, which makes decay more likely in OSB than in plywood. Of course, tree species plays a large role in this determination. OSB made from aspen or poplar is relatively susceptible to decay. In one of the biggest consumer class-action lawsuits ever, Louisiana-Pacific (LP), a building materials manufacturer, was forced to pay $375 million to 75,000 homeowners who complained of decaying OSB in their homes.