The term “plywood” used to apply only to actual plywood – an engineered wood product, made of wood veneers which are glued together with the wood grain perpendicular to the adjacent layers. That plywood still exists, but today the term can be applied to any engineered wood product which is sold in sheets. This includes such products as particle board, MDF and OSB.
Selecting the right one of these engineered wood products is an important part of a successful project. While many projects can be built out of any of them, that’s not necessarily what you want to do. Product costs, strengths and finish vary amongst them, making some products inappropriate in some circumstances, either due to the cost of the plywood product or the results it gives you.
Yet many people confuse these products regularly, making it easy to choose the wrong one and end up with less than satisfactory results on a project. Knowing the basic differences between them and what they are best for makes it easy to make the right choice and end up with a project which will last for years.
Let’s Start with Plywood
As already mentioned, plywood is an engineered wood product which consists of an odd number of wood veneers which are laid crosswise to one another and bonded together with a resinous glue. This manufacturing technique provides for a very consistent, strong product, which can withstand a lot of stress and weight. Depending on the type of plywood used and the environment, projects made of plywood can easily last 30 to 40 years, as roof sheathing and longer when used in indoor furniture.
Even within the category of plywood alone, there is a huge amount of variance, as there are many types of plywood products. These range from construction-grade plywood at the low-cost end to high-grade hardwood plywood products used in the manufacture of fine furniture and cabinetry. Specialized plywood products have been developed for marine use (making boats), aircraft manufacture and to be used in curved applications, as well as others.
Advantages of Plywood
- Plywood has more strength and can carry more weight than particle board or any other engineered wood product
- Plywood is less susceptible to moisture damage than particle board
- Plywood can be manufactured with high-grade wood veneer face and back, making it usable in the manufacture of fine furniture
- Plywood is available in a wide range of grades, making it possible to buy inexpensive or more expensive products, as the project demands
- Plywood is available in a wide range of thicknesses
- Plywood holds screws well
- Plywood is an extremely stable product, highly resistant to shrinkage, warping, twisting and cracking
- Plywood can be cut into many different shapes
- Plywood is easily painted, or stained & varnished
- Plywood is more economical than solid wood, available in much larger sizes and considerably easier to work with than having to laminate board together to get a large flat surface
Disadvantages of Plywood
- Plywood is more expensive than particle board, OSB or MDF
- Plywood is more difficult to cut, without splintering, than particle board
- Plywood edges show the layers of veneer used in its manufacture, some of which are always seen as an end grain. Therefore, it pretty much needs to be covered with something, such as a veneer edge banding
- Plywood often splinters along the edges during shipment
- Lower “construction grades” of plywood do not provide a smooth surface, so need to be hidden or covered by laminate or veneer.
What About Particle Board?
Particle board is the cheapest engineered wood panel product, considerably cheaper than plywood. The main reason that it is cheaper, is that it is made of waste from the sawmill, unlike plywood, where the veneers are cut specifically for the purpose of making the plywood.
Any wood waste can be turned into particle board, but it is predominantly made of sawdust and wood chips. These are mixed together with glue and then pressed into sheets, which are cut to size. Since the majority of the material used is extremely small, there are no long fibers to give it strength. Since wood chips and sawdust are used in its manufacture, the core of the plywood has many small voids, even though the surface is rather smooth.
Of all the engineered wood products, the particle board is the most susceptible to water damage in its unfinished state. It should always be protected from water, even when bringing it home from the lumberyard. As long as it is protected from water, it is extremely stable, less likely to warp or bow than plywood.
Advantages of Particle Board
- Particle board is the most cost-effective option when strength is not required
- Particle board has a smooth, flat surface, ideal for attaching laminates or wood veneer
- Particle board does not dent or distort easily
- Particle board is relatively lightweight, when compared to other engineered wood products
- Particle board is filled with small air pockets, giving it thermal and sound insulation properties
- Particle board is eco-friendly, as it is made of material that would otherwise be waste material from the sawmill
Disadvantage of Particle Board
- Particle board has less strength than plywood or other engineered wood panels
- Particle board readily absorbs moisture, causing swelling and damaging the surface finish
- Particle board cannot support heavy loads. When used for shelves, the weight limit of ¾” thick particle board is 25 lbs. for every three unsupported feet. For more weight, thicker particle board or supports must be used
- Particle board must be covered with laminate or painted, as the surface does not provide an attractive finish when varnished
- Particle board does not have very good screw retention capability. A number of specialty fasteners have been developed for use with it, specifically for the furniture industry
Interestingly enough, despite its disadvantages, there is a lot of low-cost furniture made of particle board, usually covered with a thin vinyl laminate. Almost all kit furniture, where the buyer needs to assemble it, is made of particle board. But that isn’t all; many furniture manufacturers use particle board extensively in their products, even in high quality furniture, in an effort to keep costs down.
Deciding Between Particle Board and Plywood
Particle board is an excellent product in cases where strength is not an issue. Vertical panels, such as the side panels in a dresser carcase are an ideal application for particle board, because the panels do not have to support any weight. However, this requires using a laminate, veneer or paint finish on the furniture piece, since the particle board cannot be stained and varnished to match the wood.
Children’s furniture, which is often painted or covered with laminate, is commonly made out of particle board. The smooth finish of the particle board works well for either laminate or paint and vinyl edging can be installed to cover up the voids in the center of the panel.
When strength is needed, it’s hard to beat plywood. The multi-layer sandwich, with wood grains crossing each other, make plywood the strongest of engineered panels. However, this comes at a higher out of pocket cost. If the plywood is not going to be covered with laminate or veneer, an even more expensive plywood is required, as the low-cost construction-grade plywoods do not have a good surface finish.
When used in fine furniture and cabinetry, hardwood plywood provides a look that is the equivalent quality of solid wood. While the grain in the face veneer is not exactly the same as in quarter-sawn boards, it is still attractive enough to be stained and varnished. Even when used in conjunction with solid pieces of hardwood, the average consumer doesn’t recognize the difference in grain.
What About Other Engineered Wood Products?
The two other major engineered wood products which can be confused with particle board are OSB and MDF. Both of these products are more expensive than particle board, as well as being stronger. But they are less expensive than plywood, while not being quite as strong.
Oriented Strand Board (OSB) commonly referred to as “chipboard” is made of thin wood chips, almost like shavings, rather than sawdust. This gives it longer strands than particle board, making it stronger. While it is not obvious to casual observation, OSB is actually made in three layers, with the top and bottom layers laid with the wood fibers oriented to the longer direction of the sheet and the thicker inner layer with the wood fibers perpendicular to its face, much like plywood.
While there are three layers, each of those layers consists of many thin pieces, which makes it possible for a sheet of OSB to consist of 50 actual layers of wood, all bonded together. Between the orientation of the wood fibers and the many layers of material, OSB is strong enough that the building code allows it to be used in place of plywood for subflooring, roof sheathing and wall sheathing.
Even though OSB can be used as a replacement for plywood in many construction applications, it really can’t be used as a substitute for particle board. The way OSB is manufactured leaves a rough surface, with the various chips not being all at the same level. It is not a good substrate for gluing laminate or veneer to and painting it brings out the unevenness in the surface.
Medium Density Fiberboard (MDF) differs from particle board and OSB in that it is made from wood fibers. Waste wood is broken down into individual fibers and then pressed together with glue to make a sheet, much like a particle board is. The big difference is that the longer fibers produce a much stronger product, without the voids which are common to particle boards.
furniture manufacturers who want a higher quality product, with more strength than particle board often choose MDF. The consistency of the product makes it extremely easy to mill with any power tool and the surface is resistant to tear-out, unlike plywood. nails and screw hold better in MDF than they do in either particle board or OSB.
The surface of MDF is smooth enough for painting or it can be covered with laminate or veneer. But the surprising thing is that the edges can be routed, sanded and then painted, providing a clean, sculpted edge, much like you can receive with wood. That’s something that can’t be done with particle board or OSB.
Failure of Any Plywood Product
All plywood products are made of essentially the same materials, wood fibers and glue. Even the types of glues used in their manufacture are limited, with the same glues used in different engineered wood products. These glues are generally the weak point of the material, eventually causing failure.
Few adhesives are truly waterproof, although most are water-repellant. But even waterproof glues can come loose, when decomposition starts breaking up the surface that they are bonded to. The combination of this decomposition and water wearing away at the glue itself is what eventually leads to the delamination of the plywood product, causing its failure.
However, delamination of plywood and delamination of the other engineered wood products we’ve discussed is considerably different. When plywood delaminates, there are still the layers of veneer remaining; at least until they decompose. When particle board delaminates, the individual wood particles can fall off, since there is nothing to hold them in place. This can quickly lead to a situation where connection between the panel and the supporting structure is lost.
Another way that delamination affects plywood products is to cause the edges of the panel to swell. This is especially true of particleboard, although it can also exist with OSB and plywood. Water absorbs through the edge of the panel first, where it can swell wood fibers, making the edge of the panel thicker. This is how some roofs end up looking like they are cupped, with the edges being higher than the rest of the roof.
Eliminating this problem in roofing is accomplished by the installation of a galvanized steel drip rail along the edge of the panel. Something similar needs to be done to protect the edges of these panels, whenever these products are used outdoors, where they are exposed to rain and moisture. If a drip edge or something similar cannot be used, the edges should be well-sealed for moisture protection.