What is Plywood?
Along with concrete blocks and lumber, plywood is one of the main staples of residential and commercial construction. Plywood is made from thin wood veneers or “plies” that are then glued together, pressed and heated to form sheets. The wood grain of the plies are rotated 90° with each alternate layer to reduce expansion and contraction of the wood. This gives plywood stability and resistance to shrinkage, breaking, warping, and cracking.
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The Plies of Plywood
The layers of veneer or plies of the plywood help determine the strength of the sheet. Plywood must have a minimum of three plies and are usually combined in an odd number of layers. The most common plies are:
- 3-ply is one of the most common types of plywood. With three layers of veneer it’s strong and durable. It can be a good choice for indoor use with a more decorative look than plywood with more layers.
- 5-ply refers to the five layers of veneers. This is common type of plywood that is suitable for a wide range of miscellaneous and construction uses where rigidity and strength are needed.
- Multi-ply plywood is mostly for exterior use and roofing. Usually designed with seven or more layers, it creates a very strong, durable home frame material that will withstand wind and weather damage.
Plywood Grades
Plywood receives grades (ranging from A to D) based on the number of blemishes on the product.
- Grade A: Both the face and back are nearly free of defects, with a smooth, sanded surface and virtually no knots. Ideal for cabinet doors and furniture and can be painted or stained.
- Grade B: Also sanded smooth, but the face and back have a few defects. These blemishes may have been repaired filler. Cheaper than Grade A.
- Grade C: Unsanded, with tight knots up to 1-½-in width. Larger sections that have been patched and filled. Good for subflooring or other applications where appearance is not important.
- Grade D: Also unsanded, with knot holes up to 2-½-in width. Generous patching and filling with some unrepaired defects. Like Grade C, good for structural uses where it will not be seen.
When two grades are indicated, such as A/B, the A refers to the face and the B refers to the back. This can save costs to the mill. The most common is B/C-grade, which is a mix of B-grade on the face side and C-grade on the back side.
Plywood Sizes
Plywood panels are generally available in three main sizes: 4-ft x 4-ft, 4-ft x 8-ft, and 4-ft x 9-ft.
You should choose the thickness depending on what type of project you have. Plywood is usually made 1/8-in thick to more than 1-1/2-in thick. Most common plywood thicknesses are ½-in, ¾-in, and 1-in.
Exterior & Interior Use
Exterior plywood is used outside the home where durability is required. Bound together using water-resistant glue that doesn’t wear off easily, this plywood is wind and weather resistant. Some of the most suitable applications for exterior plywood are walls, roof linings, and outdoor structures.
Interior plywood is not very resistant to outdoor elements and tends to degrade quickly when exposed to moisture and heat. Some of the popular applications for interior plywood include indoor furniture, interior cladding, and craft projects.
Sanded Plywood
The sanded plywood face gives a beautiful high-quality surface that is ready for finishing. It is used where outward appearance is important. And thanks to being sanded at the mill, minimal if any additional sanding is required for most applications.
Typical construction uses include stair treads and risers, cabinets and built-ins, shelving, paneling, and accent panels.
Plywood Sheathing
Exterior plywood sheathing is used on weather-protected building exteriors like roofs and walls underneath siding. Sheathing is normally rated CDX, with a C-grade face, D-grade back and X for weather exposure. It has exterior rated glue to stand up to the elements.
Plywood Underlayment
Plywood underlayment is water repellant and thicker than normal plywood, ranging from ¾-in to 1-1/8 in. It is a durable, single-layer flooring panel for use under hardwood flooring, carpet and pad, and tile and vinyl floor coverings.
Tip
Look for tongue and groove panels for a squeak-free floor. The sheet should be labeled “T&G”.
Hardwood & Softwood Plywood
Hardwood plywood is made from oak, maple, poplar, and walnut trees. It is designed for demanding end uses. Having between three and seven layers, hardwood plywood is characterized by its excellent strength, stiffness, and durability. Hardwood plywood has outstanding surface hardness, making it damage and wear resistant. This tough exterior makes it a choice for packing cases, speaker boxes, and furniture.
Softwood plywood is usually made either of Douglas fir, pine, Southern yellow pine, poplar and whitewood and is typically used for exterior frame sheathing, roof sheathing, and sub-flooring. Softwood plywood is also ideal for projects like sheds, plant boxes, doghouses, and shelving.
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Plywood is an engineered wood from the manufactured boards family which includes particle board and oriented strand board (OSB). It is made from thin sheets of veneer peeled from debarked wood. These thin layers, also called plies, are glued together in alternating right angles to create a cross-grain pattern. This pattern adds strength and stability that resists shrinkage and expansion caused by moisture.
Plywood is a popular choice in construction because of its strength and low cost. It is used in areas hidden from view that offer support such as floors, walls, roofs and garages in residential construction.
When used for roofing, plywood panels are covered and protected by other materials that keep the elements at bay, including roof felt, underlayment, flashing and shingles. When used in flooring, plywood creates a subfloor that supports hardwoods, tile and carpet floors.
Stainable and paintable plywood is ideal for shelving, cabinets and furniture. Outside the home, plywood can be transformed into fencing materials, packaging materials, scaffolding, sheds and shipping containers.
There are several common types of plywood:
Sanded plywood features face and back (top and bottom) plies that are sanded in the manufacturing process. It is used in places where it is visible, such as for cabinets, shelves and paneling.
Hardwood plywood is made from hardwoods like birch, maple and oak. The plies are glued at right angles to one another, making the plywood very strong and stable. It can be heavier than other types of plywood. Use hardwood plywood for furniture and anything that requires a strong load-bearing frame.
Plywood sheathing or structural plywood is designed for permanent structures. It is strong and inexpensive, but unfinished, and therefore not suitable for places where it will show. It should be covered by other types of materials. Use plywood sheathing for framing, beams, flooring and bracing panels.
Project plywood panels are ready-to-use, pre-cut plywood boards designed for quick and easy DIY projects. There are various types of wood, ply and plywood alternatives available. Use this for planned DIY projects when you know the measurements. It’s a great material for beginner DIYers.
Markerboard has plywood panels with a coated writing surface to use with dry erase markers only. It is ideal for craft tables or finished markerboards.
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A ply refers to a layer of veneer used to create plywood’s various thicknesses. More ply creates a thicker and stronger board. Plywood has an odd number of plies and needs at least three plies. Although specialty plywood can have any number of plies above three, most plywood is categorized as 3-ply, 5-ply or multi-ply.
3-ply is one of the most common types of plywood. It is about 2- to 3-millimeters thick and is generally used indoors, since it looks more decorative than thicker plywood boards.
5-ply is a versatile type of plywood that is about 4-millimeters thick. Use it indoors or outdoors, but avoid using for framing permanent structures, such as a shed or a home.
Multi-ply is a catchall term for plywood with seven or more plies. This plywood is strong and durable enough for use in roofing, framing and other exterior, structural projects.
Tip: Plywood with fewer plies is weaker than a plywood with more plies, even if they have the same thickness.
Plywood is sold in various ratings, grades and sizes. Make your selection based on the type of project you’re working on.
Plywood Ratings:
There are five important ratings that convey where and how to use plywood: Exterior, Exposure 1, Exposure 2, Interior and Structural 1.
Exterior means the panels have been waterproofed and can withstand inclement weather. Use exterior rated plywood for permanent outdoor structures that will be exposed to water long-term.
Exposure 1 means the panels have been waterproofed and can withstand exposure to the elements during construction. However, they are not suitable for long-term exposure post-construction.
Exposure 2 means the panels are made with an intermediate glue that is not fully waterproof. These panels can withstand occasional moisture but are otherwise intended for interior use.
Interior means the panels are not waterproof and are designed for interior use only. They should not be exposed to moisture.
Structural 1 is rated for seismic retrofit work, meaning it is designed to be earthquake resistant. Unless they have a Structural 1 rating, other plywood panels of any width are not suited for seismic retrofitting.
Plywood Grades:
There are four grades of plywood: A, B, C and D. The grade refers to the quality and appearance of the plywood’s face and back veneers. A has the highest quality and is the most expensive, and D is the least expensive.
A-grade plywood features a smooth, sanded surface without knots. Any wood defects have been repaired with synthetic filler, so the veneer can be painted. A-grade plywood is ideal for furniture or cabinet doors.
B-grade plywood also features a smooth, sanded surface, but may have more repaired defects up to 1-inch across.
C-grade is unsanded and may have several minor defects that will need to be repaired with knots up to 1 1/2 inches across, discoloration and sanding defects. C-grade plywood should be used when appearance is not important, such as for subfloors or garages.
D-grade is also unsanded with defects that have not been repaired and knot holes up to 2 1/2 inches across, discoloration and sanding defects.
You may also find ratings with two-letter classifications, such as BC. BC-grade is a mix grade plywood with one side graded a B, while the other side is graded a C.
Plywood Sizes:
The most common plywood sizes are 4- x 8-feet sheets and 5- x 5-feet sheets.
Most places also carry pre-cut project panels that are available in different sizes that may vary by store. These project panels help eliminate waste, cut costs and are easier to transport than full-size panels.
The most common thickness of plywood is 1/2-inch, but plywood thickness can range from 1/8-inch to 3/4 inches.
Contact us to discuss your requirements of melamine sheets for cabinets. Our experienced sales team can help you identify the options that best suit your needs.
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