Oriented strand board (OSB) and plywood are wood structural panels made by compressing and gluing pieces of wood together. OSB and plywood appear similar and are generally interchangeable. The different ways that each material is manufactured contribute to its unique strengths and weaknesses. While OSB developed pretty recently, it became more popular than plywood in North America by 2000. Today, nearly twice as much OSB as plywood is produced. While both products are made from different materials, and some builders strongly prefer one or the other, OSB and plywood are both manufactured according to the same performance standards.
Manufacturing process and composition
Oriented strand board is manufactured from heat-cured adhesives and rectangular-shaped wood strands arranged in cross-oriented layers. It is produced in large, continuous mats. It is a solid-panel product of consistent quality with few voids or gaps. The finished product is an engineered wood panel. It shares plywood’s strengths and performance characteristics.
Plywood is made from thin sheets of veneer (layers of wood peeled from a spinning log) that are cross-laminated and glued together with a hot press. Throughout the thickness of the panel, the grain of each layer is positioned perpendicular to the adjacent layer. The finished product is made from an odd number of layers to maintain a balance around its central access. Since it is made from whole layers of logs rather than small strands, plywood has a more consistent and less rough appearance than OSB.
Appearance
OSB is made of many strands, or smaller pieces of wood pressed together, which gives it a rougher texture. OSB, in most cases, is not preferred as a finished surface due to its rough, unfinished look. Hence it is mostly used as siding.
Plywood can have many different styles and appearances. The top layer is usually hardwood and may be any number of woods such as birch, beech, or maple. This means that the sheet of plywood takes on the appearance of the top wood. Plywood made this way is designed for building cabinets, shelves, and other items where the wood is visible. Plywood may also be made out of less-quality softwoods for its top layer. In this case, it may have knots or a rough surface. This plywood is generally used beneath the finished material, such as tile or siding.
Cost
Plywood is the more expensive option to build with than OSB. The material tends to be thicker and needs to be made to more exacting standards, which increases costs. A construction-grade plywood costs roughly ₹ 50-80/sq.ft. a sheet, while the same size sheet of OSB costs only ₹ 35-45/sq.ft. a sheet. Both cost about the same to install.
Durability
Plywood and OSB vary in terms of durability. OSB absorbs water more slowly than plywood, which can be beneficial in areas of low dampness. However, once it has absorbed water, it dries more slowly. It also warps or swells after water absorption and will not return to its original shape.
Plywood absorbs water more quickly, but it also dries more quickly. It is more likely to return to its regular shape when it dries. Plywood’s edges also resist damage better than OSB, which can crack and fray upon impact and over time.
OSB is heavier than plywood and will generally lie flatter when properly waterproofed and maintained. OSB is also more consistent than plywood. Plywood is available in many plys and different levels of quality. OSB is usually more consistent across the board, meaning what you see is what you get.
Plywood and OSB are generally considered to have the same load strength. However, as plywood has been around longer, it has been shown that it can last 50 or more years in an installation. OSB does not have the same track record because it has only been marketed for about 30 years. The proven track record of plywood often leads some people to believe that it is a more durable and longer-lasting product, but this is not necessarily true. Newer types of OSB, which have been treated to be waterproof, are likely to last just as long as plywood in similar situations.
Flooring
Plywood is generally considered the better material when used beneath flooring as a substrate. OSB flexes more than plywood. When used beneath tile, it can squeak when stepped on at best, and at worst, it may cause the grout or tile itself to crack. For that reason, plywood is usually the recommended substrate if a wood substrate is needed.
Environmental Concerns
Of the two products, OSB is considered the greener option. Because OSB is made of many smaller pieces of wood, it can be created using smaller-diameter trees, which grow more quickly and can be farmed.
Plywood, however, needs to use large-diameter trees, which are then rotary cut to produce the layers needed. Larger-diameter trees like this take much longer to grow and must be harvested from old-growth forests, making plywood a less-green option.
OSB is still being produced using formaldehyde. However, plywood must be produced without this chemical according to new environmental laws from 2019. Hardwood plywood is already available with soy-based glues and other materials that do not release urea-formaldehyde into the air. While it is possible that OSB will follow suit, it will soon be possible to find plywood without formaldehyde everywhere. Finding OSB without this chemical may be more difficult.
This comparison between OSB and Plywood will help you make the right choice as per your requirements and preference.
