Facts about different types of plywood and particle board that will help you decide which type of material is appropriate for your project.
Plywood is a manufactured laminated or pressed wood sheet used extensively in home building, carpentry, construction, and woodworking. Plywood can be used as a finishing material or as a structural element depending on the material used to fabricate the sheet. Plywood is useful due to the fact that it is stable, strong, and can cover large areas. There are several types of plywood and plywood-like products that will be discussed in this article.
Plywood is not like lumber it's made to the thickness actually stamped on its face. During the manufacturing process tolerances vary depending on the type of plywood being made. Most sanded grades of softwood plywood that are ¾ inch thick or less, are manufactured to tolerances of plus/minus 0.4 mm (1/64 inch). Most other softwood plywood, including the unsanded grades, is manufactured to a tolerance of plus/minus 0.8 mm (1/32 inch).
Hardwood plywood, which is used to build high-quality cabinets and shelving, differs slightly. Panels that are ¼ inch thick or more are made to a tolerance of plus 0.0 mm/minus 1.2 mm (3/64 inch). A plus-zero tolerance is dictated by cabinet and furniture manufacturers who can use a panel that's slightly thinner, but can’t use a thicker panel because of assembly problems.
It is important to remember that plywood swells and shrinks as it absorbs and loses moisture, like any wood product. Most of the swelling will occur in the thickness of the panel since the perpendicular nature of plywood layers tends to keep the width and length relatively stable.
Oriented Strand Board (OSB)
Oriented Strand Board, or OSB for short, is an engineered structural panel made of compressed wood strands arranged in three perpendicular layers and bonded together with a phenolic resin. Similar to plywood panels, oriented strand board is used in residential and commercial construction for sub-flooring, roof sheathing, exterior sheathing and other residential and commercial construction applications.
Available in 4’ x 8’ panels in thicknesses of 3/8”, 7/16”, 15/32”, 19/32” and 23/32”.
Three grades are available: sheathing, single floor and siding.
Medium Density Fiber Core Hardwood Plywood (MDF)
MDF is made from fine wood dust mixed with a binder and heat-pressed into panels. This material is extremely stable and is typically very consistent from batch to batch. A 3/4" thick sheet purchased over a year ago is exactly the same thickness as a new sheet purchased today. The surface below the veneer is typically free of voids and blisters, resulting in a better veneer consistency and bond. With this better bonding of the wood veneer, there is less chipping during sawing and routing.
The primary drawback to this product is weight. A 3/4" x 4' x 8' sheet can weigh as much as 70 to 90 pounds per sheet. The density of the core is expressed as the weight of a one cubic foot (1'x1'x1') block of the material. Therefore, an MDF sheet using a 48# (pound) core, will weigh 96 pounds. (48"x96"x3/4"= 2 cubic feet).
Medium- and High-Density Overlay Plywood (MDO and HDO)
MDO and HDO consist of a core material, like laminated fir veneer, overlaid with a pressed fiber material. This is standard veneer core plywood with an MDF surface. This produces a weight that is lower than a full MDF, but the surface is more stable than veneer core plywood.
Veneer Core Hardwood Plywood (VC)
Veneer Core plywood is made from alternating layers of fir slices, common plywood, where the surface can have a veneer of a finished wood grain such as oak or maple. This construction gives VC plywood a distinct advantage over others in strength. This is a light weight material, and easy to handle.
The drawbacks of VC plywood are:
Voids in the core and face are common.
VC is not always consistent in thickness from sheet to sheet, or within the same sheet.
During sawing some layers will be ripped and other layers will be crosscut. This makes cutting this material with a fine laminate blade more difficult, with a greater tendency to burn.
The saw-cut edges are not as clean and smooth as the other products, so this material does not take edge gluing as well.
The inconsistency in the pre-veneered surface can result in thin spots in the veneer.
Lumber Core Plywood
Lumber Core Plywood is manufactured from strips of solid lumber, typically poplar or basswood. This is one of the most expensive plywood types and is commonly used for applications where the edges cannot be concealed or need to be routed.
Particle Board Core Plywood (PBC)
PBC uses a coarser wood dust than MDF. Because of this, it has a slightly lower weight, but the edges and surfaces are not as smooth and consistent. Most melamine products use PBC as the substrate.
Melamine plywood is a thermally fused, resin saturated paper finish over a particle board core. It is highly stain and abrasion resistant. Melamine is not the name of the paper finish; it's the name of the resin used to impregnate the paper finish.
This material comes in a variety of colors which is resistant to staining and marring. This type of plywood is used in cabinet making. The surface of the melamine is brittle and can chip during machining.
High Density Plywood
High density plywood (HDP) is usually made from maple or birch. Unlike common plywood, HDP has many more plies, is generally void free, and uses a stronger species than fir. HDP is commonly used for drawer side material as it is strong, stable, and has a moderately attractive edge.
Varying thicknesses are available. The most common are 1/4”, ½”, and 3/4”.
Sheets usually measure 4’x 8’. Other sizes may be available through special order, usually in 2-foot increments up to 16 feet in length.
Most common wood type is Douglas fir and Southern pine.
Available in a wide range of grades, with the most common being C-D, Exposure 1 commonly called CDX.
Another popular grade is A-D Exposure 1, which is suitable when only one paintable side is needed.
A popular grade is A-C EXT, which has one paintable surface and can be used outside.
Type A-A EXT is also available if both sides will be exposed.
Plywood siding is also available, and comes in standard patterns such as texture 1-11, reverse board and batten and others.
Some manufacturers apply a water-resistant coating to repel water during the normal construction cycle which can reduce warping and added moisture inside the structure when finishing.