One of the more recent questions that comes up is: What is the difference between OSB and Plywood?
The main difference between the two is how they are made. Plywood is made up of several (often 4 or 5) layers of wood veneer. Each layer is glued to its neighbors, with the grain of the layer running perpendicularly. This means that there is no realistic chance that the plywood will split, because the grain of the wood is glued together in a way that is not dissimilar to fabric. Splits follow the grain of the wood, but the grains run in different directions, so it is far less likely.
OSB is formed in a similar way, but instead of the plys being made by sheets of wood veneer, the plys are made by gluing together smaller chips of wood. These peices of wood are glued together so that their grains run together. These plys are then glued together in a way similar to plywood. When the plys are glued together, they are put under a great amount of pressure, so that the glues will set and create a strong bond.
Structural Comparision
For most uses in building, OSB and plywood are essentially interchangable. You must be sure that the thicknesses of the panels are of the same magnitude, though. One of the better ways to make sure that you are comparing apples to apples, so to speak, is to check for the APA (American Plywood Association) stamp on the sheet of material. That means that the plant that produced the material has undergone rigorous testing, and that its product is constantly tested for strength and quality.
The one area in which there is a large difference between plywood and OSB is impact holes. OSB tend to handle severe impact to its surface less well than plywood. This should come as no surprise. Plywood is cut into continuous veneer sheets, so that there are longer, solid pieces of wood fiber. OSB is made of smaller pieces that do not extend quite that far. Once it is installed onto studs or rafters this becomes less of a factor, since the OSB and plywood are supported more evenly.
|
Fasteners
It is generally thought that OSB does not hold fasteners as well as plywood does. There have been studies that show this to be false. The biggest factor that seems to arise, though, is whether the fastener is countersunk at all. By countersinking into OSB, the strength of the panel begins to be compromised. The fibers of the panel are broken, and there is less material beneath the fastener, so of course there will be a weak spot around a nail head or staple.
Moisture
OSB is somewhat more prone to water absorption than plywood. This is really only a factor when there is water in liquid form coming into contact with the OSB. When this happens, there is a good chance of up to 15-20% swelling. What this means is that many finished floor vendors will not warantee their products over an OSB substrate. The swelling could crack grout joints, or create humps underneath linoleum.
We do carry a relatively new OSB style product called Advantech that has a guarantee that there will not be any need to sand down spots of swelling. It differentiates itself from the OSB market, in that it is considered a structural panel. What this means is that it is constructed in a different way that does not allow for the same levels of moisture.
|
