San Antonio Roofing: Article About Roof Sheathing Materials
Roof sheathing is generally made out of plywood, but that is not the only option. Oriented strand board, also known as OSB, is quite popular as well. These two types of wood products make up the vast majority of residential sheathing installed by San Antonio roofing companies.
Plywood and OSB are quite similar. Both are made out of wood fibers compressed into slabs of particle board. They are not nearly as strong as solid wood but are much lighter and much cheaper.
The enemy of nearly all roofing products is water, and these two roof sheathing products are no exception. They both tend to swell quickly and absorb a lot of water. OSB comes from the factory with resin sealed edges, so it is more resistant to this than plywood. However, some sheets of sheathing must be cut to fit the roof. The cut edges of plywood absorb less water than the cut edges of OSB.
OSB is cheaper and lighter than plywood, but plywood is stronger. Experts are divided on which material is better. The savings when choosing OSB are not huge, but they are sizable. However, plywood is stronger, which means it is less likely to break and need repair. The strength of plywood means that it is relatively heavy, which does place a lot of stress on the structural beams it sits on.
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OSB is lighter and therefore does not put as much stress on the beams.
Neither of these two materials is clearly better than the other; there are alternatives, but they are rarely used in residential applications. In fact, they may not even be available for the average homeowner to buy, depending on the area. Two alternatives are fire resistant OSB and plywood. These panels of sheathing are hard to come by for residential use and may not even be of much benefit to the homeowner. Fire resistant sheathing is very expensive and is generally only used by companies that are required to do so by their insurers. These companies usually operate in buildings that are at a high risk of catching on fire, such as factories, restaurants and gun ranges. Fires started in these locations may burn very hot due to the materials within the structures. The fire resistant panels will help slow such fires, but they may not be of appreciable benefit to homeowners because they are specifically designed for fires that burn hotter than the average house fire.