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Types of Plywood

Uses of Plywood 

Plywood is an engineered wood from the manufactured boards family, which also 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 usually used in areas that are hidden from view in a post-construction capacity. The most common uses for plywood include support for floors, walls, roofs and garages in residential construction.  


When used for roofing, plywood panels are covered and protected by a variety of building materials that keep the elements at bay, including roof felt, underlayment, flashing and shingles. When used in flooring, plywood functions as the subfloor that supports hardwoods, tile and carpet floors.  


Plywood makes up most of the walls and floors in attics and are sometimes found in laundry rooms, closets and other unfinished areas in the home. It can also be made into fencing materials, packaging materials, scaffolding, shelving, sheds, shipping containers, cabinets and furniture. 



Types of Ply                                                              

Close up of a multi-ply plywood panel that shows the distinct layers of veneer.

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. 

Ratings, Grades & Sizes                                          

Palettes of plywood panels stacked on top of each other.

Plywood is sold in various ratings, grades and sizes. Make your selection based on the type of project you’re working on. 

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.  


Grades 

We carry 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. 


Sizes 

The most common size for plywood sheets is 4- x 8-feet, followed by 5- x 5-feet.  

We 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. 


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. 


Choose the types of plywood you need for your projects based on where and how you’ll be using the panels. Depending on the type of project you’re working on, project panels or plywood alternatives can save you time and money.