Types of Plywood

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.

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.

You can use other types of boards in place of true plywood. They may even be commonly referred to as plywood, despite being manufactured differently. Although not technically plywood, other engineered wood boards and panels can be great options for construction projects when you want to save money or have a different look and feel.

When choosing plywood or a plywood alternative, consider these features as well:

Stainable plywood provides an already sanded surface that accepts stain well to create a natural-looking finish.

Paintable plywood readily accepts paint and laminate for a unique and customized appearance.

Pressure treated plywood resists damage from water, weather, decay and insects.

Plywood with tongue and groove edges are designed to snap together easily while creating a strong and tight joint between panels.