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Oriented strand board vs plywood: Which one should you chose for your green home

Both oriented stand board (OSB) and plywood are panels of wood made by compressing and gluing bits of wood together. Even though OSB and plywood look similar, the manufacturing process followed for each of them makes them unique with their own strengths and weaknesses. OSB is generally considered to be more Eco-friendly than plywood and is used more in building Eco-friendly homes.

Why and how are they made?

1. OSB. It is made by cutting the logs into pieces which are later dried, organized and treated using wax and other binders. These strands are later grouped into big sheets and pressed together at a very high temperature. OSB is a solid-panel product of good quality with little or no gaps. OSB has all the strength and performance characteristics of plywood and looks almost similar to natural wood.

2. Plywood. It is made from thin layers of veneer (thin layers of wood peeled from a spinning log). The layers of veneer are glued together using resins. The layers of veneer are cross-laminated and hot pressed to form a wooden plank. Plywood has odd number of veneer layers to maintain balance around its center. Since plywood is made from complete layers of logs rather than pieces of log, it looks softer than OSB.

OSB for a green home

OSB was released in the American market in the late 1970s but became quickly popular. It became popular with builders and contractors due to its economical price and environment-friendly properties when compared with plywood. By the year 2000, nearly twice the quantity of OSB is produced to plywood in North America. But, OSB is not preferred much as a building material in countries out of North America. OSB is very inexpensive, when compared with plywood. It will cost nearly US $700 less to build a 2, 400 square feet home using OSB than using plywood.

OSB is considered as an environment-friendly material for building a green home, when compared with plywood due to many reasons. OSB boards are made using smaller diameter trees like poplars, southern yellow pine and mixed hardwood species that are often cultivated in farms. Broken wood pieces are also used in making OSB boards. New trees can be grown, when the older trees are cut and consumed for making OSB. In the manufacturing process of OSB, very less wood fiber extracted from the trees is wasted, when compared with the manufacturing process of plywood. In contrast, plywood is made using larger diameter trees from forests. These larger diameter trees cannot be grown back quickly once they are cut and consumed. Sometimes, it may take decades to grow back these larger diameter trees. Cutting off bigger trees from older forests will lead to deforestation and increase the carbon content in the environment. Smaller diameter trees grow faster (sometimes less than a year) and can be cultivated just like any other cash crop in the fields.

OSB boards are generally made in bigger sizes when compared with plywood which reduces the wastage, when it is cut into desired shapes during the construction process. OSB boards are more consistent (so have fewer soft spots) and stronger, when compared to plywood sheets. These qualities increase the durability of OSB boards. Durable OSB boards can be helpful in both reducing the cost of replacing the boards in constructing the house and maximizing your recycling efforts.

There are some problems involved with the usage of OSB as building material. OSB is very heavy, when compared with plywood and needs more support to install it properly. It also puts more stress on the house. OSB is less moisture-resistant, when compared with plywood. The edges of OSB boards are susceptible to swelling, when they are exposed to significant amounts of water or moisture. The edges may expand by up to 15 percent and may remain permanently swollen to some degree. Swelling can at times be a nuisance as it will lift materials that lie about it like carpets and tiles. But, swollen plywood boards generally come back to their normal shape once it is dry. Nails and screws will remain firmly in place in case of plywood than in the case of OSB.

One important caution, when using OSB, is that it emits more of a gas called formaldehyde, than plywood. This gas is emitted from the glue used to make the boards. Formaldehyde is carcinogenic and very dangerous, when inhaled by both children and adults. Hence, OSB boards should be left out in the open for a few weeks after procurement till the gases are vented out. Apart from some of the problems associated with OSB, it makes a better Eco-friendly choice than plywood for building a green home.

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