Since its introduction in the mid-1800s, plywood has grown in popularity and use. Today, over 700 million cubic feet of plywood is manufactured and used every year. The number of plywood products has grown significantly, now including a large number of engineered wood products, such as OSB, MDF and particleboard. Likewise, the number of uses for plywood has increased, as people continue to find new ways of using these products.
While most woodworkers are accustomed to referring to multi-layered wood panels where adjacent layers are glued together with the grain running in perpendicular directions as plywood, the term has become more generalized. Today, the term “plywood” refers to all engineered wood products available in sheet form. Typically, plywood is available in 4 ft. by 8 ft. sheets in the US, although other sizes are available.
What makes plywood so popular is this availability of large, flat, stable sheets, without having to go through the work of laminating wood planks together. Compared to the cost of making such a laminated sheet, the cost of plywood, even hardwood plywood is considerably cheaper, even without taking labor into consideration.
Plywood sheets are also stronger than laminated boards, as the grain runs in both directions, eliminating the risk of the panels being weaker with the grain than across the grain. Of course, different plywood products have different overall strengths, depending on how they are made.
Much of the plywood manufactured is used in the building of new homes. This is mostly softwood plywood, with lower face grades, but also includes a considerable amount of OSB, which is an allowable substitute for softwood plywood in many instances, according to the current building code.
Plywood is an important part of wood frame home construction not only because it can cover a larger area that boards can, reducing labor and material cost, but because it provides structural stability to the home. A framed wall or roof is not stable in and of itself, because it is largely made of rectangles, which are not a structurally stable form, without cross-bracing. Attached plywood sheathing acts as cross-bracing, while covering the structure.
Walls and roofs are both covered with either softwood plywood or OSB sheathing, either ½” or 5/8” thick, providing this structural stability and an unbroken surface for siding and roofing to be installed onto. While not needed so much for stability, ¾” thick plywood or OSB is also installed as a subfloor, over floor joists, to provide a strong, stable surface to mount flooring on. Thinner plywood panels are used for soffits and other exterior areas which need to be covered, but do not need as much structural strength.
Plywood is also used in indirect ways in forming the structure of the home. A number of structural components, such as I-Joists and Microlam beams are made of plywood, reducing the overall material cost, while improving the home’s structural strength.
Some specialty types of plywood are used in construction as well, such as T-111 siding. This is a rough surfaced softwood plywood, with a surface that is slotted for texture, something like paneling. Typically, T-111 siding is manufactured as tongue-&-groove panels for easier installation without gaps.
Cabinets & Furniture
Cabinetry of all types, whether architectural cabinetry or furniture casings, is made of plywood today; generally hardwood plywood or birch plywood. Plywood provides an easy and cost-effective way of manufacturing furniture and cabinetry, without the need to take the time to laminate boards together. While laminated boards are still used in high cost furniture, the price reflects the extra material cost and high labor of building in that way.
Using plywood in cabinets and furniture eliminates the problems of working with warped, cupped or twisted boards, the scourge of carpenters and cabinetmakers for centuries. While plywood usually needs some sort of structural support to counter the natural cupping of the plywood sheets, this is minimal compared to the problems that can come with boards.
Hardwood plywood also lowers the cost of furniture and cabinetry in that only the face and reverse face are covered with the hardwood veneer, while the core veneers are normally softwood, which is less expensive. Therefore, the actual material cost is lowered considerably.
Sanded softwood plywood is also used for manufacturing furniture, especially furniture pieces which will be painted, rather than stained and varnished, such as furniture for children’s rooms. The use of sanded softwood plywood lowers the cost even further, while maintaining high strength.
Going even lower on the cost scale, particle board has become the standard in low-cost home furnishings of the type popularized by IKEA and now available through the big box stores and manufactured by a host of different companies. Particle board provides for lower manufacturing cost, even while it requires the use of more expensive hardware. However, this lower cost furniture does not last as long and is easily damaged during moving.
Boats have long been manufactured from wood. While most boats today are made with fiberglass hulls, plywood is still used extensively in their structure. This use of plywood is extensive enough to warrant a separate type of plywood, marine-grade plywood. This plywood is also used for decking and cabinetry inside the cabin of the boat.
What makes marine-grade plywood unique is not that it is waterproof, as some assume, but that it has no voids in it. Voids in plywood are a good place for moisture to gather, starting the wood veneer swelling and causing bubbles and delamination. By eliminating the voids, marine grade plywood is less likely to have those problems. Much of the marine grade plywood is also WBP (Water Boil Proof), which means it has been tested in boiling water, proving that the adhesive used in laminating the plywood won’t delaminate from exposure to moisture.
Marine grade plywood has such a good reputation that it is used widely in the manufacture of other products which require high-quality plywood which won’t delaminate. One such application is the floorboards of city transit buses, which are made of 5’ x 8’ x ¾” thick marine grade plywood.
Decks & Docks
While decks and boat docks are usually made of boards, often using types of wood which are less likely to be damaged by soaking up water, such as pressure-treated wood, cedar and redwood, as well as an ever-increasing variety of composite materials, they can also be made of plywood, especially in cases where speed of construction is needed and appearance is not as high a priority.
While a deck or dock made of boards is more attractive than one covered with plywood, it is less expensive to build with plywood. The smoother surface of plywood also helps prevent the loss of small items that would otherwise fall through the cracks. This can be a real advantage for fishing piers.
Since plywood provides a smooth, unbroken surface, decks and docks can be covered with exterior-grade carpeting, Astroturf and other exterior floor coverings, providing comfort and good traction for walking.
During World War II there was a huge amount of experimentation into aircraft design, seeking out materials that were found in abundance for use, rather than making them all out of aluminum. The British Wellington bomber used a varnished linen fabric skin, which turned out to be quite durable. Here at home, the Douglas C-54 military transport and the Lockheed P-38 fighter were made of plywood, amongst other famous aircraft.
While the day of plywood aircraft has passed, manufacturers still produce aircraft plywood for restoration work. This plywood is flexible enough that it is also used for a number of decorative architectural applications, such as making curved walls and reception desks in lobbies of commercial buildings.
Crates & Cases
While most packing crates are made of corrugated cardboard today, plywood is still in wide use for crates which require stronger material, especially when heavy industrial equipment or valuable pieces of artwork are being shipped.
Likewise, plywood is used in the manufacture of custom cases, such as those used for the shipping of sound and lighting equipment used by music groups and traveling entertainers. Plywood is a much easier material to work with, in the manufacture and customization of these cases, than other available materials, while having the strength to support the weight of the equipment and protect it from rough handling.
Interior wood paneling for homes and offices is a plywood product; generally ¼” thick panels, with the wood grain surface either printed directly onto the plywood’s surface or a vinyl laminate. A thinner, but similar paneling is used for the interior of recreational vehicles, which typically have 1/8” thick birch paneling, covered with vinyl laminate on the inside. Some upscale recreational vehicles use a thin hardwood plywood instead.
Arts & Crafts
The low cost and flexibility of plywood has made it the material of choice for a large range of arts and crafts projects, both those made by crafter and those manufactured commercially. Plywood panels, especially thin plywood panels, can be bought in crafts stores for a wide variety of projects.
Projects such as barn quilts are often painted onto plywood panels, as the plywood provides a smooth flat surface to paint onto. Likewise, murals are often painted on plywood, making it possible for the work to be completed in the artist’s studio and then transported to the final location for installation.