Oriented strand board or OSB sheathing is a less expensive alternative to plywood. The material is made out of flakes or strands of wood that are bonded together using resin. It is typically used in roofing, decks, walls and subfloors. The material, however, is very different from that of plywood because OSB sheathing does not have any gaps. It is also comparably stiffer and stronger. Before buying, OSB sheathing, here are some things to consider.
Understanding the composition of the OSB sheathing is the key to understanding the effectiveness of using the material. To understand it better, it is best to compare it with traditional plywood. Although the sheathing is also made from wood, it makes use of strands or flakes and bonded together using resin. Unlike plywood, OSB sheathing makes use of wood from fast growing trees, therefore making it a more environmental-friendly option. Typical types of wood used to build the material include southern yellow pine, poplar, aspen, and a mixture of other types of soft hardwood. These hardwoods are considered and termed soft because they are physically soft; nonetheless, these soft hardwoods are still part of the hardwood family.
Type of Binders Used
The strength of the sheathing depends on the type of binder used. Some types of OSB sheathing are bound together by waterproof resin to provide moisture resistance and internal strength. If the sheathing is to be used at a place where humidity is quite high, sheathing with waterproof resin is the best choice. For indoor use, buy OSB that uses phenol-formaldehyde or methyl diphenyl diisocyanate binders to avoid health hazards. OSBs that use urea-formaldehyde as a binder often emit gasses that contain formaldehyde, a very toxic material.
Fake and Original OSB
Many OSBs out there are fake. Before buying OSBs from a wood supply store, make certain that the OSBs have an APA label. An APA label differentiates original OSBs from impostors. Some types of boards also look like OSB, such as fiberboards and waferboards. If not sure what to look for in an OSB, always ask for guidance from the storeowner.
The reason why some people prefer OSB from plywood is because it is usually cheaper by $3 to $5. However, certain projects may be more cost-effective when using plywood. Prices of OSB and plywood always depend on the law of demand and supply. If the prices are right, OSB can be more cost effective than plywood. Always ask for a price list before deciding which to purchase.
OSB is bonded using resin, thus making it harder to coat with chemicals used to protect it from moisture or fire. Since the wood used in its manufacture is relatively softer than most hardwoods, the size of OSB sheathing may be distorted once it is exposed to high humidity. For this reason, it should never be used in areas exposed to moisture. However, there are specialized OSB sheathings designed to be exposed to weather. These sheathing are coated with waterproof resin and are marked with the “EXTERIOR” label.